Building Damage Caused by Deflection of Reinforced ...

Publisher’s version / Version de l'éditeur:

Technical Translation (National Research Council of Canada), 1970

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la

première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez

pas à les repérer, communiquez avec nous à [email protected].

Questions? Contact the NRC Publications Archive team at

[email protected]. If you wish to email the authors directly, please see the

first page of the publication for their contact information.

NRC Publications Archive

Archives des publications du CNRC

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien

DOI ci-dessous.

https://doi.org/10.4224/20331587

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

Building Damage Caused by Deflection of Reinforced Concrete

Building ComponentsMayer, H.; Rusch, H.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site

LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

NRC Publications Record / Notice d'Archives des publications de CNRC:https://nrc-publications.canada.ca/eng/view/object/?id=91796828-06c7-4269-a556-83da9e33dcfb

https://publications-cnrc.canada.ca/fra/voir/objet/?id=91796828-06c7-4269-a556-83da9e33dcfb

NATIONAL RESEARCH COUNCIL OF C A N A D A

T e c h n i c a l T r a n s l a t i o n 1412

T i t l e : B u i l d i n g damage c a u s e d by d e f l e c t i o n of r e i n f o r c e d c o n c r e t e b u i l d i n g components

(Bauschaden a l s F o l f e d e r Durchbiegung von S t a h l b e t o n - Baut e i l e n )

Authors : H o r s t Mayer and Hube r t RCsch

R e f e r e n c e : D e u t s c h e r Ausschuss fGr S t a h l b e t o n , H e f t 1 9 3 , B e r l i n 1967 . 90 p .

T r a n s l a t o r : J . H . R a i n e r , B u i l d i n g P h y s i c s S e c t i o n , D i v i s i o n o f B u i l d i n g R e s e a r c h , N a t i o n a l Resea rch C o u n c i l

PREFACE

The problem of deflection damage in reinforced concrete structures has been of interest to the Division of Building Research in connection with its technical support role to the Associate Committee on the National Building Code. The widespread occurrence of loss of serviceability and visual cases of damage in concrete structures, particularly in connection with partition walls supported by concrete members, emphasizes the importance of studying the causes which contribute to this phenomenon.

The extensive survey of damage and subsequent analysis carried out and reported by the Testing Institute for Materials and Structures of the Technical University, Munich, Germany, represents an important contribution to an understanding of the cause of deflection damages in reinforced concrete buildings. The remedial or preventive measures which are suggested, both in the design phase as well as during con- struction, should prove to be of interest to designers, builders, and researchers concerned with the uses of reinforced concrete.

The translation has been prepared by J.H. Rainer, Research Officer, Building Physics Section, Division of Building Research, and checked and revised by D.A. Sinclair, Chief Translator, National Science Library, National Research Council.

Ottawa

May 1970

N.B. Hutcheon Director, DBR/NRC

FOREWORD

Damage i n a f i n i s h e d s t r u c t u r e can u s u a l l y be t r a c e d t o u n s a t i s f a c t o r y c o n s t r u c t i o n methods . The e v i d e n c e s o f damage and t h e i r c a u s e s a r e numerous. The t y p e s o f damage t r e a t e d i n t h i s r e p o r t , how- e v e r , c o n s t i t u t e a s p e c i a l c a t e g o r y . A s a r u l e t h e y o c c u r r e d due t o u n e x p e c t e d l y l a r g e d e f l e c t i o n s o f r e i n f o r c e d c o n c r e t e components t h a t have i n t h e l a s t few y e a r s been o b s e r v e d w i t h i n c r e a s i n g f r e q u e n c y .

Already i n 1958 t h e German R e i n f o r c e d Concre t e A s s o c i a t i o n found i t d e s i r a b l e t o i n v e s t i g a t e t h e c a u s e s o f e x c e s s i v e d e f l e c t i o n s o f r e i n f o r c e d c o n c r e t e b u i l d i n g components and t o a d o p t s u i t a b l e m e a s u r e s . It was shown t h a t t h e d e f l e c t i o n c a l c u l a t i o n s commonly u s e d u n t i l t h e n were u n s u i t a b l e s i n c e an unc racked s e c t i o n ( S t a t e I ) was assumed and c r e e p and s h r i n k a g e o f t h e c o n c r e t e had been n e g l e c t e d . Dur ing t h e d e l i b e r a t i o n s i t became a l s o a p p a r e n t t h a t i t was t h e n n o t p o s s i b l e t o recommend r e l i a b l e methods o f a n a l y s i s and r e l e v a n t l i m i t i n g v a l u e s f o r

a maximum p e r m i s s i b l e d e f l e c t i o n .

I n o r d e r t o remove t h i s u n c e r t a i n t y v a r i o u s r e s e a r c h programs were c a r r i e d o u t , one o f which i s t h e s u b s e q u e n t c o l l e c t i o n and a n a l y s i s o f o b s e r v e d c a s e s o f b u i l d i n g damage.

The f i n a n c i a l s u p p o r t f o r t h i s i n v e s t i g a t i o n was p r o v i d e d by t h e F e d e r a l M i n i s t r y o f Housing and C i t y C o n s t r u c t i o n , t o whom s p e c i a l t h a n k s a r e e x t e n d e d h e r e w i t h . Warm t h a n k s a r e due a l s o t o t h e members o f t h e Task F o r c e on D e f l e c t i o n s o f t h e German R e i n f o r c e d C o n c r e t e A s s o c i a t i o n , p a r t i c u l a r l y t o P r o f e s s o r s Dr . - Ing . G . F r a n z , Dr . - Ing . S .

H a s e n j g g e r , Dr . - Ing . F . L e o n h a r d t , Dr . - Ing . A . Mehmel, and Dr . - Ing . K .

P i e p e r . We a r e p a r t i c u l a r l y g r a t e f u l t o a l l f e d e r a l and s t a t e o f f i c i a l s a s w e l l as t h e numerous p r i v a t e c o n c e r n s and e n g i n e e r i n g d e s i g n o f f i c e s f o r t h e i r a c t i v e s u p p o r t i n t h e a c q u i s i t i o n o f p l a n s and c a l c u l a t i o n s needed f o r t h e e r a l u a t i o n o f o b s e r v e d b u i l d i n g damage. Only t h e i r co- o p e r a t i o n p e r m i t t e d a r e l i a b l e and a l m o s t comple t e t r e a t m e n t o f a l l t y p e s o f d e f l e c t i o n damage.

RES UME

Le r appor t concerne l t 6 t u d e d tun grand nombre d l i n c i - den t s cons t a tks s u r des cons t ruc t ions en b6ton arm6 e t ayant pour cause e s s e n t i e l l e l a d6formabi l i t6 excess ive des 616ments f l 6 c h i s . Parmi l e s 181 d6c la ra t ions d l i n c i d e n t s , obtenues p a r une enquste , 115 s o n t suffisamment compl6 t e s pour permet t re une analyse . Les cons6 - quences d f u n inc iden t k t an t p a r f o i s mu l t ip l e s , e l l e s peuvent s t r e c l a s s6es dans l e s ca t ego r i e s nu ivantes :

106 cas: d6sordres dans l e s c lo i sons e t murs de r e f end ;

60 cas : flGche t r o p importante du p l anche r ;

39 cas : f i s s u r a t i o n des blkments en bkton armk;

29 cas : f i s s u r e s h o r i z o n t a l e s l t a p p u i d lun plancher ;

13 cas : endu i t s e t revstements endommagks;

1 2 cas : dommages p a r t i c u l i e r s diis awr d6formations;

259 dommages d i s t i n c t s , re lev6s s u r 181 cas d t i n c i d e n t s ,

Les dksordres dans l e s c lo i sons endommagkes l e s p lus f rkquents r 6 s u l t e n t de l a f l e x i b i l i t 6 d i f f b r e n t e de l a c l o i s o n e t de son suppor t , l a c l o i s o n formant un panneau r i g i d e vis-A-vis de l r6lkment dlappui f l e x i b l e en b6ton arm6 dont l a d6formation augmente encore sous l l e f f e t du r e t r a i t e t du f luage . Afin d l 6 v i t e r ces dksordres , i l con- v i e n t de r6dui re l a f l e x i b i l i t k des poutres-supports su ivant une formule indiqu6e dans c e t expos6 ou de c h o i s i r un genre de c lo i son qui s o i t i n d i f f 6 r e n t aux a f fa i ssements d i f f b r e n t i e l s de son support .

Les 6lBments A f a i b l e hauteur e t soumis A de f o r t e s charges sont l a cause e s s e n t i e l l e de dommages pa r d6formation ex- c e s s i v e ~ . I1 f a l l a i t s u r t o u t redouter des dksordres pour l e s planchers r e c t a n g u l a i r e s po r t an t dans l e s dewr sens , pour l e s q u e l s l e r6glement allemand a u t o r i s a i t jusqul a l o r s une hauteur p lus rkdui t e que pour l e s planchers ne po r t an t que dans un sens. Pour l a f l 6che admissible d lun plancher on a adopt6 l a va l eu r de f = L/300,

Tous l e s a u t r e s genres de d6sordres d6coulent essen- t i e l l e m e n t de f a u t e s commises dans l t k t u d e du p r o j e t ou dans l l e x 6 c u t i o n du bGtiment. Le prksent rappor t c i t e e t d k c r i t p l u s i e u r s dommages c a r a c t k r i s t i q u e s .

Ensui te v i e n t un bref r6sumk des expkriences f a i t e s 6 116t ranger e t une spBc i f i ca t ion des p r inc ipes de base 6 r e s p e c t e r a f i n d l k v i t e r des i n c i d e n t s par dkformations excess ives .

CONTENTS

1. Introduction (Synopsis)

2. Statement of the Problem

Page

1

3. Region Covered by the Survey of Structural Damage

4 . Types of Structural Damage Which Have Occurred

5. The Types of Flexural Component Which Produced the Most Frequent Cases of Damage

5.1 Number of Participating Types of Building Components

5.2 Comparison of the Behaviour of One-Way Slabs With Two-Way Slabs

6. The Effective Slenderness Ratio of Reinforced Concrete Flexural Members That Have Contributed to Damage

7. Theoretical Determination of the Probable Deflection of the Reinforced Concrete Support Members Involved in a Case of Damage

7.1 Characteristic Values, Loads, Internal Forces and Deformation Constants

7.2 Calculation of Terminal Deflection Values

7.3 Magnitude of Deflections Which Initiated Damage

7.4 Coefficients of Deformation Which Were Calculated Simultaneously With the Deflection

8. Factors Responsible for the Occurrence of Deflection Damage

8.1 'Theoretically Possible Sources of Damage

8.2 Actual Causes of Damage

8.3 Connection Between Origin and Type of Damage

9. Evlauation of Partition Wall Damage

9.1 Types of Partition Wall Damage Observed

9.2 Limiting Values for the Initiation of Partition Wall Cracks

9.3 Means of Preventing Partition Wall Cracks in the Future

10. Evaluation of Excessive Slab Deflections

10.1 Magnitude of Permissible Slab Deflection

10.2 Measures by Which Excessive Deflections Can Be Prevented

11. Evaluation of Observed Cracks in Reinforced Concrete Building Components

12. Evaluation of Horizontal Cracks in the Vicinity of Slab Supports

Evaluation of Damage to Plaster and Finishes

Evaluation of Deflection Damage in Isolated Cases

Results of Questionnaire on Deflection Damage in Other Countries

15.1 Reports of Cases of Damage

15.2 Studies of Deflection Damage in Other Countries

15.3 Deflection Limitations of Reinforced Concrete Components in Various Countries

Summary

Figures and Table 1

References

List of Symbols

Appendix - List of Tables of the Most Important Data on Each Individual Case of Damage

Sketches and Drawings for the Various Cases of Damage

Photographs

BUILDING DAMAGE CAUSED BY DEFLECTION OF REINFORCED

CONCRETE BUILDING COMPONENTS

1. INTRODUCTION ( S y n o p s i s )

I n t h i s r e p o r t v a r i o u s t y p e s o f damage t o b u i l d i n g s h a v e been c o l l e c t e d and e v a l u a t e d . The damage was c a u s e d p r i m a r i l y by e x c e s s i v e d e f l e c t i o n o f r e i n f o r c e d c o n c r e t e s t r u c t u r a l p a r t s . I n res- ponse t o a q u e s t i o n n a i r e , 1 8 1 c a s e s o f damage were r e p o r t e d : 115 o f t h e s e c o u l d b e e v a l u a t e d s a t i s f a c t o r i l y . I n most c a s e s a number o f c a u s e s c o n t r i b u t e d t o t h e damage. A l t o g e t h e r t h e f o l l o w i n g c a s e s were r e p o r t e d :

106 r e p o r t s o f damage t o t h e p a r t i t i o n w a l l s

60 r e p o r t s o f e x c e s s i v e s a g g i n g i n t h e c e i l i n g

39 r e p o r t s o f c r a c k s i n t h e r e i n f o r c e d c o n c r e t e s t r u c t u r a l p a r t s

29 r e p o r t s o f h o r i z o n t a l c r a c k s i n t h e r e g i o n o f t h e c e i l i n g s u p p o r t s

1 3 r e p o r t s o f damage t o p l a s t e r and w a l l c o v e r i n g

1 2 r e p o r t s o f d e f l e c t i o n o f i s o l a t e d c a s e s

t o t a l o f 259 r e p o r t s i n 1 8 1 c a s e s .

The damage t o t h e p a r t i t i o n walls r e s u l t s f rom t h e f l e x - i b i l i t y o f t h e r e i n f o r c e d c o n c r e t e p a r t s s u p p o r t i n g t h e r i g i d w a l l s . The d e f o r m a t i o n o f t h e s u p p o r t s i n c r e a s e s i n t i m e owing t o c r e e p and s h r i n k a g e . The damage can b e a v o i d e d e i t h e r by i n c r e a s i n g t h e t h i c k n e s s o f t h e s u p p o r t s - t h e f u n c t i o n o f s p a n - l e n g t h i s p r e s e n t e d i n t h e f o r m u l a - o r by c o n s t r u c t i n g a s u i t a b l e p a r t i t i o n w a l l .

The s a g g i n g a p p e a r s ma in ly i n s l e n d e r , h i g h l y - s t r e s s e d s t r u c t u r a l p a r t s . The p a r t s o f t h e c e i l i n g w i t h c r o s s e d r e i n f o r c e m e n t s a r e p a r t i c u l a r l y s u s c e p t i b l e t o damage. U n t i l r e c e n t l y , t h e s p e c i f i c - a t i o n s f o r r e i n f o r c e d c o n c r e t e i n Germany a l l o w e d a g r e a t e r d e g r e e o f s l e n d e r n e s s f o r t h e s e p a r t s t h a n f o r c e i l i n g s r e i n f o r c e d i n o n l y one d i r e c t i o n . The d e g r e e o f s a g g i n g p e r m i t t e d i s f = L/300.

I n a l l o t h e r c a s e s damage was c a u s e d ma in ly by e r r o r s i n d e s i g n o r c o n s t r u c t i o n . A number o f c a s e s o f c h a r a c t e r i s t i c damage are p r e s e n t e d and d e s c r i b e d . F i n a l l y , a s u r v e y w i l l b e g i v e n o f f i n d i n g s

from a b r o a d and a l i s t o f i m p o r t a n t r e q u i r e m e n t s t o p r e v e n t f u r t h e r dam- a g e t h r o u g h s a g g i n g .

STATEMENT OF THE PROBLEM

I n r e c e n t d e c a d e s c a s e s o f s t r u c t u r a l damage i n newly c o n s t r u c t e d b u i l d i n g s have been o b s e r v e d w i t h i n c r e a s i n g f r e q u e n c y and a r e t h o u g h t t o have a r i s e n f rom e x c e s s i v e d e f l e c t i o n o f r e i n f o r c e d con- c r e t e b u i l d i n g components . Such damage became a p p a r e n t o n l y a f t e r a c e r t a i n p e r i o d o f u s e , o r became more pronounced w i t h t i m e . Thus, p a r t i t i o n walls p l a c e d on f l e x i b l e r e i n f o r c e d c o n c r e t e s l a b s c r a c k e d ;

the slabs themselves frequently exhibited large deflections which were considered unsightly or led to depressions in which water accumulated and caused damage to the roof membrane. In addition, other types of damage were reported as is shown in greater detail in Section 4.

These types of damage had previously not been observed to such an extent. Their causes must therefore lie in the technical applic- ation of progressively higher concrete and steel stresses, and the use of large spans and slenderer members. Consequently, under working load the reinforced concrete flexural members no longer remain chiefly in State I* but in a majority of cases have already passed into State 11* with a cracked tension zone. Simultaneously, the creep deformation of the concrete has increased.

These developments mean, therefore, that the previously satisfactory rules, which were based on decades of experience, must now be expanded and the deformation behaviour of the building components must henceforth be carefully considered so that damaging consequence to other build in^ components can be avoided by suitable design measures.

These considerations led the German Reinforced Concrete Association (DAfStb) in 1958, even before the new revision of the German Reinforced Concrete Code DIN 1045 had been concluded, to propose a temporary change in the hitherto applicable provisions. How- ever, during the deliberations it became apparent that it was neither possible to give a characteristic value for the permissible deflection magnitude that would be valid for all uses, nor did sufficiently reliable documents exist for the prediction of the expected deflections.

In order to avoid further instances of damage, or at least to diminish their extent, the Association decided despite these uncertainties, to propose new rules for the deflection limits of re- inforced concrete building components in an addendum to DIN 1045. This supplementary specification has been in use since 1959. It is based mainly on a limitation of the deflection slenderness ratio R/h of the building component, depending on the concrete and steel stresses. Un- fortunately, this sometimes resulted in uneconomical slab thicknesses and did not always prevent the undesirable cracking of partition walls.

Thus further studies were needed in order to provide a reliable basis for eventual control. Various research programs were initiated, beginning in 1959, by the Materials Testing Laboratory for Structures of the Technical University, Munichn*. First of all, measure- ments were made of the time-dependent deflections of completed reinforced concrete flexural members (see Ref. 1). This work was intended to yield numerical values which would describe the actual behaviour of structures, and thus make it possible to determine the constants needed for the structural analysis.

Translator's Notes:

* State I represents the uncracked concrete section State I1 represents the cracked concrete section

** German title: MaterialprUfunpamt fiir das Bauwesen der Technischen Hochschule ~Gnchen (MPA)

The second p r o j e c t , d e s c r i b e d h e r e i n , i s t o i n v e s t i g a t e t h e e x t e n t and t y p e s o f b u i l d i n g damage which a c t u a l l y o c c u r as a con- s equence o f d e f l e c t i o n s of r e i r l f o r c e d c o n c r e t e b u i l d i n g components . The i n d i v i d u a l c a s e s o f damage have been a s s e s s e d unde r un i fo rm c l a s s i f i c a t i o n s and an a t t en ip t h a s been made t o e s t a b l i s h t h e t y u e c a u s e s of t h e damage. The f i n a n c i a l s u p p o r t came f rom t h e F e d e r a l M i n i s t r y :'ora B u i l d i n g C o n s t r u c t i o n , t o which w e e x t e n d o u r p a r t L c u l a r t h a n k s .

F i n a l l y , a t h i r d s t u d y dete17mined methods o f how d e r l e c - t i o r s u n d e r a c t u a l c o n d i t i o r l s may be c a l c u l a t e d ( 3 ) . These s u g g e s t i o n s have beell a p p l i e d t,o t h e c a s e s o f damage c o l l e c t , e d h e r e .

3 . REGIO1.J COVLRED BY THE SURVEY OF STRUCfI'URAL DAMAGE

The s u r v e y of t h e d e f l e c t i o n damage el-~compassed ma in ly t h e F e d e r a l R e p u b l i c o f Germmy. The s e n i o r b u i l d i n g a u t l i o r i t i e s o f t h e 11 Fede r i i l s t a t e s d i s t r i b u t e d a c i r . c u l a r from t h e Materials T e s t i n g 1 n s t i l ; u t e f o r S t r u c t u r e s o f t h e T e c h n i c a l U r l i v e ~ s i t y Munich t o a l l a p p r o p r i a t e b u i l d i n g i n s p e c t i o n o f f : i c e s , s t a t e b u l . l d i n g o f f i c e s and i n s p e c t i o n e n g i n e e r s . A t t h e same t i m e , a l l b u i l d i n g m a t e r i a l . t e s t i n g s t a t i o n s , stai:e b u i l d i n g s c h o o l s , i n : 3 t i t u t e s of t e c h n i c a l u n i v e r s i t i e s and a l l consu l t i i ng o f f i c e s who might p o s s i b l y have been c o n s u l t e d I n t h e evaluation o f d e f l e c t i o n damage were c o n t a c t e d . A t o t a l o f agp rox ima%ely i ,000 q u e s t i o r l n a i r * e s were d i s t r ' l b u t e d .

Independen t o f t h e s u r v e y of t h e M a t e r i a l T e s t i n g J n s t L t u t e f o r S t r u c t u r e s o f t h e T e c h n i c a l Universi1;y Munich, t h e Eaus t ah lgewebe GMBH* D u s s e l d o r f , i n t h e s r , r i n g o f 1961 , had a l s o c a r r i e d o u t a s t a t i s t i c a l i r ~ v t l s t i g a t i o n o f d e f ' l e c t i o n damage. These r e s u l t s have k i n d l y been made a v a i l e b l e 50 u s 'or f u r t h e r e v e l u a t i o n . T h i ~ , e f f o r t conce rned l t s e l f w i t h t h e b u i l d i n g c o o p e r a t i v e s , p a r t i c u l a r - l y i n t h e s t a t e s o f I i o rd rhe in -Wes t f a l en and N i e d e r s a c h s e n . Of t h e 105 b u i l d i n g c o o p e r a t i v e s zu rveyed , o n l y two d e f l e c t i o n damage were r e p o r t e d . They weye i n c l u d c d i n t h e damagc a n a l - y s i s c a r r i e d o u t h e r e i n . F'our o t h e r o:?ganizat?-ons knew o f "some c a s e s " . However, f u r t h e r . d e t a i l s c o u l d n o t be obya ined . T h r e e c o o p e r a t i v e s had m i s t a k e n l y r e p o r t e d o t h e r b u l - l d i n g danrage t o be due ?.o excessrj ve d e f l e c t i o n s .

P. view o f t l i e r e g i o n s cove red by t h e s u r v e y i s g i v e n i n P i g . 1. The c i r c l e s s i g n i f y t h a t t h e o T g a n i z a t j o n s who were q u e s t i o n e d knew of' no d e f ' e c t f o n damage. The c r o s s e s s y m b o l i z e t h a t one o r more c a s e s o f d a ~ a g e liave been r e p o r t e d . From t h e d i s t r i c t s which do riot c c n t a i n any symbol , n e i t l ~ e r a pos i1 . ive : lor a n e g a t i v e rinswer t o t h e s u r v e y was r e c e i v e d . I t mey w e l l be conc luded t h a t i n t i ~ i s c a s e no d e f l e c t : on damagc had been known.

I n o r d e r t o o b t a i n a p i c t u r e of t h e e x t e n t o f d e f l e c t i o n damage i n o t h e r c c u n t r i e s , a n a d d i t i o n a l 200 q u e s t , i o n n a i r e s wer.e d i r e c t e d t o t,he main i n t e r n a t i o n a l i n s t f - t u t e s and t o well-known a u t l ~ o r i t , i e s a b r o a d . I n t h i s s u r v e y , a l l European c o u n t r i e s i n c l u d i n g t h o s e o f t h e e a s t e r n b l o c k , were j n c l u d e d , as w e l l as t h e niain c o u n t r i e s o f Nor th and S o u t h Amer'ca, A u s t r a l i a , I n d i a and J a p a n . S e c t f o n 1 5 r e p o r t s b r i e f l y a b o u t t h e r e s u l t s o f t h i s :i.nl'or.mational s u r v e y .

T r a n s l a t o l a ' s Note:

* L i t e r a l t r a n s l a t i o n o f company name: B u i l d i n g S t e e l Wire-Mesh L t d .

4 . TYPES OF STRUCTURAL DAMAGE WflICH HAVE OCCURRED

A t o t a l o f 1 8 1 c a s e s o f damage were r e p o r t e d . F o r 115 o f t h e s e s u f f i c i e n t s u p p o r t i n g m a t e r i a l was made a v a i l a b l e f o r a r e - c a l c u l a t i o n s o t h a t t h e y c o u l d be e v a l u a t e d s a t i s f a c t o r i l y . I n 25 c a s e s o n l y few d e t a i l s a r e known. About t h e r e m a i n i n g o n e s o n l y t h e f a c t t h a t a d e f l e c t i o n damage had o c c u r r e d c o u l d b e e s t a b l i s h e d .

F i g u r e 2 c o n t a i n s an e n u m e r a t i o n o f v a r i o u s damage p o s s i b i l i t i e s and t h e c o r r e s p o n d i n g f r e q u e n c i e s o f t h e i r o c c u r r e n c e . A s c a n be s e e n , two t y p e s o f damage p r e d o m i n a t e among t h e many c a s e s r e p o r t e d . One c a n , however , g roup t h e v a r i o u s p o s s i b i l i t i e s l o g i c a l l y i n t o s i x l a r g e r c a t e g o r i e s as h2.s a l r e a d y been i n d i c a t e d i n t h i s f i g u r e . I n tile e v a l u a t i o n t h e s e w i l l be d e s c r i b e d h e r e a f t e r i n more d e t a i l u n d e r t h e i n d i v i d u a l s e c t i o n s .

P a r t i t i o n w a l l damage c o n s t i t u t e s t h e most i m p o r t a n t g r o u p . T h i s i n c l u d e s n o t o n l y c r a c k s i n t h e w a l l s ( I ) , b u t a l s o l a r g e gaps i n t h e v i c i n i t y o f b a s e b o a r d s , a n d h o r i z o n t a l c r a c k s a t t h e j o i n t be tween w a l l and c e i l i n g ( 2 ) . I n a d d i t i o n , c o m p l a i n t s a b o u t jammed d o o r s ( 3 ) must a l s o b e i n c l u d e d i n t h i s g roup ( s e e S e c t i o n 9 ) .

The second most i m p o r t a n t damage g roup s t ems f rom e x c e s - s i v e s l a b d e f l e c t i o n s ( 6 ) , and i n c l u d e s t h e f o r m a t i o n o f t r o u g h s i n r o o f s ( 7 ) and c o m p l a i n t s a b o u t s l a n t i n g f u r n i t u r e ( 1 0 ) ( s e e S e c t i o n 1 0 ) .

A f u r t h e r damage g roup c o n s i s t s o f p l a s t e r ( 8 ) and f i n i s h i n g damage ( 9 ) due t o e x c e s s i v e s l a b d e f l e c t i o n s ( s e e S e c t i o n 1 3 ) .

A s a s e p a r a t e damage g roup may b e l i s t e d a l l c a s e s o f damage due t o e x c e s s i v e r o t a t i o n o f t h e r e i n f o r c e d c o n c r e t e edge beams. T h i s i n c l u d e s h o r i z o n t a l c r a c k s above o r below c e i l i n g s u p p o r t s ( 1 6 ) , a s w e l l as e x c e s s i v e l a t e r a l b e n d i n g d e f l e c t i o n s o f s t e e l o r c o n c r e t e columns ( 1 7 ) ( s e e S e c t i o n 1 2 ) .

I n c l u d e d i n a f u r t h e r damage g roup were t h e c r a c k s i n r e i n f o r c e d c o n c r e t e components , f o r i n s t a n c e , c r a c k s which o c c u r on t h e t o p s u r f a c e o f s l a b s a l o n g t h e l i n e s o f s u p p o r t , t h e c r a c k s a t t h e e n d o f t h e s o l i d edge s t r i p ( 1 8 ) , o r t h e c r a c k s o b s e r v e d normal t o t h e d i a g - o n a l i n t h e c o r n e r s of two-way r e i n f o r c e d p l a t e s ( 1 9 ) ( s e e S e c t i o n 1 1 ) .

F i n a l l y , a l l r e m a i n i n g d e f l e c t i o n damage which have o c c u r r e d o n l y i n i s o l a t e d i n s t a n c e s were c o l l e c t e d i n a s e p a r a t e damage g r o u p : c o l l a p s e o f p a r t i t i o n s ( 4 ) ; m o i s t u r e s e e p a g e ( 5 ) ; s h a t t e r i n g o f shop windows ( 1 1 ) ; f a c a d e c o n s t r i c t i o n ( 1 2 ) ; s e p a r a t i o n o f j o i n t s ( 1 3 ) ; l e a k s i n t i l e s t o v e s ( 1 4 ) ; v i b r a t i o n phenomena ( 1 5 ) ; and u n a c c e p t a b l e d e f o r m a t i o n s ( 2 0 ) ( s e e S e c t i o n 1 4 ) .

The damage c a t e g o r i e s men t ioned above o c c u r r e d w i t h t h e f o l l o w i n g f r e q u e n c y :

P a r t i t i o n w a l l damage 106 t i m e s

E x c e s s i v e s l a b d e f l e c t i o n 60 f f

Cracks i n r e i n f o r c e d c o n c r e t e components 39 "

H o r i z o n t a l c r a c k s i n t h e v i c i n i t y o f s l a b s u p p o r t s 29 "

Damage t o p l a s t e r aild f i n i s h e s 1 3 t i m e s

1 s o l . a t e d d e f l e c t z o n damage 12 t i m e s

The t o t a l number of p o s s i b l e t y p e s of damage i s g r e a t e r t h a n t h e r e p o r t e d 1 8 1 c a s e s o f damage, s i n c e o f t e n niore t h a n one p o s s i b i l i t y c o u l d be o b s e r v e d i n a s i n g l e i n s t a n c e .

5 . THE TYPES OF FLEXURAL COMPONENT W H I C H PRODUCED THE MOST FREQUENT

CASES OF DAMAGE

5 . 1 Number o f P a r t i c i p a t i n g Types o f B u i l d i n g Components ---------------------------------------------------- The m a j o r i t y o f i n s t a n c e s o f damage o c c u r r e d i n two-way

r e i n y o r c e d s l a b s and r i b b e d s l a b s , a s shown i n F i g . 3. T h i s i s no doubt b e c a u s e f o r m e r l y two-way r e i n f o r c e d components were allowecl. t o be c o n s t r u c t e d w i t h a g r e a t e r s l e n d e r n e s s r a t i o %han one-way r e i n f o r c e d components. U n t i l t h e i n t r o d u c t i o n of t h e addendum t o D I N 1045 two-way r e i n f o r c e d p l a t e s wit l t f o u r s i d e s s imply supportecl c o u l d have s l e n d e r n e s s r a t l o s up t o 50, whereas one-way r e i n f o r c e d s l a b s c o u l d b e b u l l t o n l y up t o R/h = 35.

The above c o n j e c t u r e i s s u b s t a n t i a t e d by t h e spec ia .1 a n a l y s i s shown i n F i g . 4 , i n which o n l y t h o s e b u i l d i n g compoi~ents a r e i n c l u d e d whose t h e o r e t i c a l s l e n d e r n e s s r a t i o i s Ri/h ( 35, o r t h o s e f o r which t h e s l e l ~ d e r r l e s s r a t i o i s n o t a p p a r e n t f rom t h e aamage r e p o r t . Here R i i s t h e e q u i v a l e n t span l e n g t h which i s f u r t h e r d e s c r i h e d i n S e c t i o n 6 , and which p e r m i t s a compar'.son o f e f f e c t i v e s l . e n d e r n e s s r a t i o unde r n rb i1 , r a ry s u p p o r t conditions ( c o n t i n u o u s , c a n t i l e v e r , e t c . ) . Of t h e 156 damage c a s e s i n P i g . 3 , 88 a r e a l r e a d y e l i m i n a t e d by t h e above ment ioned l i m i t a t i o n of s l e n d e r n e s s r a t i o . It i s no tewor thy t h a t 63 clamage c a s e s o c c u r I n two-way r e i n f o r c e d components and c n l y 1 5 i n t h o s e w i t h one-way r e i n ~ r o r c i n g . It canno t y e t be s t a t e d w i t h c e r t a i . n t y from t h i s r ~ u r e l y s t a t i s t i c a l c o n s i d e - a t i o n whe the r a l l 88 c a s e s c o u l d a c t u a l l y have been a v o i d e d by a s t r i c t e r l i m i t a t i o n o f t h e s l e n d e r n e s s r > a t i o . A s w i l l be shown i n S e c t i o n 3, t h e s l e n d e r n e s s r a t i o s h o u l d be d e t e r m i n e d a s a f u n c t i o n of t h e span l e n g t h R i .

I n F i g . 4 i t Is shown t h a t a l l t y p e s of b u i l d i n g components e x h i b j - t e d c a s e s o f damage. The empty columns i n t h e p r e s e n t a t i o n s h o u l d n o t l e a d t o a f a i s e c o n c l ~ : s i o r i , f o r t h e y r e s u l t mere ly from a s y s t e m z t i c a p p l i c a t i o n o f t h e chosen a l p h a b e t i c a l scheme and r e p r e s e n t b u i l d i n g components which a r e o n l y r a r e l y o r n e v e r produced. Moreover, i n t h e c o n t e x t o f p r o b a b i l i t y t h e o r y t h i s c o n s t i t u t e s a compara t i .ve ly s m a l l sarr.ple which can d e s c r i b e t h e b e h a v i o u r of t h e whole p o p u l a t i o n o n l y a p p r o x i m a t e l y .

5 . 2 Comearison of t h e Behaviour of One-Way Sla.bs w i t h Two-Way S l a b s -..- ------------------.--------------------------.---------------

Comparison o f F i g . 3 and 4 showed t h a t t h e r e i s n o j u s t i f j c a t i o n f o r g i v i n g two-way s l a b s g r e a t e r s l e n d e r n e s s t h a n one-way s l a b s . F i g u r e 7 o f t h e n e x t s e c t i o n p r o v i d e s a more t h e o r e t i c a l conf i rm- a t i o n o f t h i s . A s a. c a l c u l a t i o n shows, t h e d e f e c t i o n of a s l a b w i t h f o u r - s i d e d s u p p o r t i s g r e a t e r t h a n t h a t of a s l z b w i t h two-s ided s u p p o r t i f t h e c u r v a t u r e M/EI a t t h e c e n t r e i s t h e same f o r b o t h t y p e s o f s l a b s . The d i f f e r e n c e s are g r e a t e s t f o r a s q u a r e p l a t e . I n o r d e r t o g e t e q u a l d e f l e c t i o n b e h a v i o u r , i t s s l e n d e r n e s s r a t i o woul6. have t o be r educed by 6 p e r c e n t i n t h e c a s e o f s i m p l e s u p p o r t s on a l l s i d e s and 1 5 p e r c e n t

i n t h e c a s e o f comple te ly f i x e d s u p p o r t s , compared w i t h t h e s l a b s u p p o r t e d on two s i d e s . Fo r t h e s a k e o f s i m p l i c i t y , however, i t i s recommended t h a t t h e two t y p e s be t r e a t e d i d e n t i c a l l y a s f a r as t h e s l e n d e r n e s s r a t i o i s conce rned .

6 . THE EFFECTIVE SLENDERNESS RATIO OF REENFORCED CONCRETE FLEXURAL MEMBERS

THAT HAVE CONTRIBUTED TO DAMAGE

The s l e n d e r n e s s r a t i o o f a b u i l d i n g component i s u s u a l l y u n d e r s t o o d t o be t h e r a t i o o f span l e n g t h t o h e i g h t . The h e i g h t i s t a k e n e i t h e r a s t h e e f f e c t i v e d e p t h h o r t h e t o t a l c r o s s - s e c t i o n a l t h i c k n e s s do. I n t h e f o l l o w i n g , h w i l l be u s e d .

The s l e n d e r n e s s r a t i o i s a rough measure o f d e f l e c t i o n b e h a v i o r . The g r e a t e r t h e s l e n d e r n e s s r a t i o t h e g r e a t e r i s t h e d e f l e c - t i o n unde r o t h e r w i s e i d e n t i c a l c o n d i t i o n s . These o t h e r c o n d i t i o n s a r e : i d e n t i c a l l o a d i n g , c o n s t a n t moment o f i n e r t i a a l o n g t h e s p a n , i d e n t i c a l c r e e p and s h r i n k a g e b e h a v i o u r o f t h e c o n c r e t e , and t h e same s t r u c t u r a l con- f i g u r a t i o n . The l a t t e r c o n d i t i o n can be a c c o u n t e d f o r by t h e i n t r o d u c t i o n o f a n e q u i v a l e n t member. The o t h e r c o n d i t i o n s w i l l b e n e g l e c t e d f o r t h e s a k e o f s i m p l i c i t y .

The d e t e r m i n a t i o n o f t h e span l e n g t h s R i o f t h e s u b s t i t - u t e beam can o c c u r i n v a r i o u s ways. Only one Q f t h e f o l l o w i n g two groups o f c o n d i t i o n s d e s c r i b i n g e q u a l i t y o f d e f o r m a t i o n and s t r e s s i n t h e a c t u a l and t h e s u b s t i t u t e beams h a s t o be s a t i s f i e d a t any one t i m e .

(1) Deformat ion C o n d i t i o n s ......................

Same a b s o l u t e d e f l e c t i o n f Same r e l a t i v e d e f l e c t i o n f/R Same maximum s l o p e o f t h e d e f l e c t i o n c u r v e , max. t a n a Same maximum end r o t a t i o n , max.

@ A

( 2 ) S t r e s s C o n d i t i o n s -----------------

Same l o a d i n g q Same s t r e s s a t t h e c e n t r e s e c t i o n a m Same c u r v a t u r e a t t h e c e n t r e s e c t i o n (M/EI),, o r Same maximum s t r e s s , max, a

An e x t e n s i v e d i s c u s s i o n o f t h e a rguments which e n t e r i n t o t h e c h o i c e o f t h e most s u i t a b l e measures o f comparison can be found i n t h e p u b l i c a t i o n by A . Mehmel ( R e f . 2 ) . I n t h e a n a l y s i s c a r r i e d o u t h e r e t h e f o l l o w i n g d e f i n i t i o n o f t h e e q u i v a l e n t span l e n g t h s was a d o p t e d , i n agreement w i t h Mehmel and t h e p r o p o s a l s f o r t h e new e d i t i o n o f t h e German R e i n f o r c e d Concre t e Code:

For t h e e q u i v a l e n t span l e n g t h t i , t h e s p a n o f a s imply s u p p o r t e d beam w i t h c o n s t a n t moment o f i n e r t i a s h o u l d be chosen i n such a manner t h a t unde r u n i f o r m l y d i s t r i b u t e d l o a d i n g t h e same r a t i o o f c e n t r e - l i n e d e f l e c - t i o n t o span l e n g t h and t h e same c u r v a t u r e a t t h e c e n t r e - l i n e s e c t i o n e x i s t a s i n t h e a r b i t r a r i l y s u p p o r t e d beam under c o n s i d e r a t i o n . F o r a c a n t i l e v e r , t h e d e f l e c t i o n a t t h e f r e e end and t h e c u r v a t u r e a t t h e r e s t r a i n e d s e c t i o n a r e t o be compared.

Expres sed i n f o r m u l a e , t h e s e d e f i n i t i o n s a r e as f o l l o w s ( F i g . 5 ) :

lli = k - l l

C o n d i t i o n ( 1 ) (same r e l a t i v e d e f l e c t i o n )

C o n d i t i o n ( 2 ) (same c u r v a t u r e )

When c o n c e n t r a t e d and l i n e l o a d s were p r e s e n t i n a d d i t - i o n t o t h e un i fo rm l o a d , t h e d e f l e c t i o n o f t h e a r b i t r a r i l y s u p p o r t e d beam was c a l c u l a t e d a c c o r d i n g t o t h e well-known d e f o r m a t i o n laws o f s t a t i c s and compared w i t h t h e v a l u e s o f a s imply s u p p o r t e d beam under un i fo rm l o a d i n g . For v a r i a b l e moments o f i n e r t i a o f t h e a r b i t r a r i l y s u p p o r t e d beam t h e same p r o c e d u r e was f o l l o w e d .

With t h e a i d o f t h e t h e o r e t i c a l r e l a t i o n s h i p f = c.(M/EI)m-l12 and t h e two c o n d i t i o n s d e s c r i b e d above , t h e d e s i r e d f a c t o r k f o r t h e d e t e r m i n a t i o n of t h e s u b s t i t u t e span l e n g t h can be f o r m u l a t e d a s f o l l o w s :

From C o n d i t i o n ( 1 ) : C . ( M / E I ) ~ ' ~ = (5 /48 ) (M/E1)m 'e 'k

By i n t r o d u c i n g Cond i t ion (2) we o b t a i n c = ( 5 / 4 8 ) k

For t h e s p e c i a l c a s e o f a uni form l o a d and c o n s t a n t moment o f i n e r t i a , t h e f a c t o r k f o r a beam e l a s t i c a l l y r e s t r a i n e d a t b o t h ends i s o b t a i n e d a c c o r d i n g t o F i g . 6 from t h e fo rmula

f o r t h e e l a s t i c a l l y r e s t r a i n e d c a n t i l e v e r

For two-way r e i n f o r c e d s l a b s t h e f a c t o r k was d e t e r - mined i n a s i m i l a r manner and i s shown i n F i g . 7 . T h i s f i g u r e was u s e d f r e q u e n t l y d u r i n g t h e damage a n a l y s i s . Bu t , a s h a s a l r e a d y been mention- e d i n S e c t i o n 5 , one s h o u l d n o t d i f f e r e n t i a t e i n p r a c t i c e be tween two-way

and one-way s l a b s i n t h e d e t e r m i n a t i o n o f t h e e q u i v a l e n t s p a n l e n g t h .

It s h o u l d be n o t e d , however, t h a t i n t h e d e t e r m i n a t i o n o f t h e a p p r o p r i a t e d e f l e c t i o n s l e n d e r n e s s o f a two-way s l a b , t h e e q u i v a l e n t span l e n g t h and

n o t t h e l a r g e s t g e o m e t r i c a l s p a n l e n g t h s h o u l d a lways be u s e d . A s can

be s e e n from t h e example shown i n F i g . 8 , t h e g r e a t e s t s p a n l e n g t h can

y i e l d t h e s m a l l e s t d e f l e c t i o n s l e n d e r n e s s r a t i o unde r c e r t a i n s u p p o r t c o n d i t i o n s and span l e n g t h r a t i o s . T h i s i s t h e c a s e f o r a l l t h e t y p e s o f s l a b s i n d i c a t e d by d o t t e d l i n e s i n F i g . 7 .

F o r s l a b s s u p p o r t e d on t h r e e s i d e s , t h e e q u i v a l e n t s p a n l e n g t h can no l o n g e r be d e t e r m i n e d l o g i c a l l y a c c o r d i n g t o t h e above-

ment ioned d e f i n i t i o n , s i n c e t h e s l a b normal t o t h e f r e e edge canno t be cons i -dered a s a c a n t i l e v e r p l a t e n o r a s a s l a b s u p p o r t e d on two s i d e s . I t s u p p o r t s i t s e l f e l a s t i c a l l y i n t h e o t h e r d i r e c t i o n . It i s recommended t h a t i n t h i s c a s e t h e s p a n l e n g t h p a r a l l e l t o t h e f r e e edge be c o n s i d e r e d a s t h e g o v e r n i n g o n e .

7 . THEORETICAL DETERMINATION OF THE PROBABLE DEFLECTION OF THE REINFORCED

CONCRETE SUPPORT MEMBERS INVOLVED I N A CASE OF DAMAGE

Only i n a few c a s e s h a s t h e magni tude o f t h e d e f l e c t i o n t h a t c a u s e s t h e damage been measured . U s u a l l y , a s p e c i a l i s t was con-

s u l t e d on ly a f t e r a c o n s i d e r a b l e l a p s e o f t i m e f o l l o w i n g t h e o c c u r r e n c e o f d i s t u r b i n g phenomena, and d u r i n g t h e e x a m i n a t i o n an i n i t i a l d e f l e c t i o n v a l u e was e s t a b l i s h e d . T h i s v a l u e , however , i n c l u d e s t h e form-work camber and i s c o n s e q u e n t l y u n r e l i a b l e . I n c o n n e c t i o n w i t h t h e d e f l e c t i o n damage a n a l y s i s c a r r i e d o u t h e r e i t was t h e r e f o r e n e c e s s a r y t o c a l c u l a t e t h e d e f l e c t i o n s t o be e x p e c t e d f o r e v e r y s i n g l e c a s e o f damage on t h e b a s i s o f t h e most r e a l i s t i c a s s u m p t i o n s .

However, t h e c a l c u l a t i o n s were a l s o n e c e s s a r y f o r a s econd r e a s o n . They p e r m i t t e d a s y s t e m a t i c r e v i e w o f t h e consequences o f a l l c a u s e s o f damage. Thus, t h e r e l a t i v e impor t ance o f i n d i v i d u a l c a u s e s c o u l d be weighed a g a i n s t each o t h e r and a d d i t i o n a l c a u s e s c o u l d be d i s c o v e r e d which might n o t y e t have been r e c o g n i z e d by t h e l o c a l e x p e r t .

The b a s i s f o r t h e s e d e f l e c t i o n c a l c u l a t i o n s w i l l sub- s e q u e n t l y be d e s c r i b e d b r i e f l y . F u r t h e r d e t a i l s , p a r t i c u l a r l y t h e co- e f f i c i e n t s u s e d , can be o b t a i n e d from t h e d i s s e r t a t i o n by t h e f i r s t a u t h o r ( R e f . 3 ) .

7 . 1 C h a r a c t e r i s t i c V a l u e s , Loads , I n t e r n a l F o r c e s and Deformat ion ............................................................. C o n s t a n t s ---------

The s t r u c t u r a l s y s t e m o f t h e l o a d - b e a r i n g r e i n f o r c e d c o n c r e t e members i n v o l v e d , a s w e l l a s t h e i r d imens ions and m a t e r i a l prop- e r t i e s , have been o b t a i n e d from t h e formwork and r e i n f o r c i n g p l a n s . The most s i g n i f i c a n t d a t a a r e c o n t a i n e d i n t h e t a b l e s o f t h e Appendix.

The i n d i v i d u a l damage c a s e s have been p r e s e n t e d t h e r e

i n a s y s t e m a t i c s e q u e n c e , F i r s t come t h e t y p e s o f p a r t i t i o n w a l l damage a r r a n g e d a c c o r d i n g t o t h e magni tude o f t h e e q u i v a l e n t span l e n g t h , min. R i . Then, s t a r t i n g from c a s e 9 2 , we have t h e c o m p l a i n t s o f e x c e s s i v e s l a b d e f l e c t i o n , p r o v i d e d t h a t s i m u l t a n e o u s l y p a r t i t i o n w a l l damage h a s n o t o c c u r r e d . These have a l s o been a r r a n p e d a c c o r d i n g t o t h e e q u i v a l e n t span l e n g t h . S i m i l a r l y , s t a r t i n g from c a s e 133 , h o r i z o n t a l c r a c k s i n t h e v i c i n i t y o f s l a b s u p p o r t s ; f rom c a s e 144 , c r a c k s i n t h e r e i n f o r c e d c o n c r e t e component; and from damage c a s e 1 5 4 , i s o l a t e d c a s e s o f d e f l e c - t i o n damage where t h e r e i s a d e f i n i t e cause f o r c o m p l a i n t . Concern ing

t h e i n s t a n c e s o f damage s t a r t i n g a t 163 , i t i s known o n l y t h a t a d e f l e c - t i o n damage had o c c u r r e d .

The l o a d i n g o f t h e b u i l d i n g components was d e t e r m i n e d anew by o u r own r e - c a l c u l a t i o n . I n a d d i t i o n t o t h e dead w e i g h t , o n l y t h e p r o b a b l e p e r m a n e n t l y - a c t i n g l i v e l o a d was a p p l i e d . Fo r l i v i n g a r e a s ,

t h i s l i v e l o a d was assumed a t 50 k I ? h 2 , and f o r commercial p r e m i s e s , depend ing on t h e t y p e oT u s a g e , a t approximately 100 t o 200 kp/m2.

S jmi l ; . r ly , t h e i n t e r ' n a l fo r>ces wei7e newly d e t e r r ~ i n e d artd, a s f a r a s p o s s i b l e , compared w i t h t h e T ~ a l u t ? s o f t h e o r i g i n a l s t a t i c s c a l c u l a t i o n s . I n do ing s o , 2.n att;ernpt was rrlade t o c o n s i d e r , a s f a r as p o s s i b l e , a l l e f f e c t s : f o r exarrple changes i r ~ s t r e s s e s due t o r e i n f o r c e - ment b e i n g p l a c e d t o o low, o r p a r t i a l r e s t r a i n t s i n t h e edge s u p p o r t s which a r e nor.mally n e g l e c t e d i n s t a t i c s c a l c u l a t i o n s . The d e g r e e s o f r e s t r a i n t t h u s o b t a i n e d were r e c o r d e d i n t h e c o r r e s p o n d i r ~ g s k e t c h e s o f t h e s t r u c t u r a l . sy s t em i r ~ t h e Appendix.

I n d e t e r m i n i n g t h e modulus o f e l ~ . s t i c i t y of t h e c o n c r e t e t h e i n f l u e n c e o f t h e stlless l e v e l was a l s o c o n s i d e r e d . The f l e x u r a l t e n s i l e s t r e n g t h of t h e concre+,e was o b t a i n e d fr20rn t h e b a s i c v a l u e o f a permanently w e t t e d c o n c r e t e as w e l l a.s a number o f i n f l u e n c e c o e f f i c i e n t s ( d i f f e r e n t i a l . d r y j n g o f t h e c r o s s s e c t i o n , i n f l u e n c e o f t h e s i z e e f f e c t s , d e t e r l o r a t i o n o f s t l - e n g t h due t o p e r n ~ a r ~ e n t and c y c l i c l o a d s , e t c . ) .

The c r e e p c o e f f i c i e n t 4 . and t h e s h r i n k a g e c o e f f i c i e n t E~

were t a k e n from t h e v a l u e s o b t a i n e d a t t h e MPA* MunLch o f t h e Comit6 Europgen du E6ton ( C E B ) ( R e f . 4 ) . Both t h e s e v a l u e s depend n o t o n l y on t h e t e m p e r a t u r e and humid i ty o f t h e a i r s u r r o u n d i n g t h e b u i l d i n g component, b u t a l s o on t h e comy,osi t ion o f t h e c o n c r e t e (cement c o n t e n t and water /cement r a t i o ) and on t h e t ime o f i n i t i a l . l o a d i n g . Also i m p o r t a n t a r e t h e p o s s i b i l i t i e s o f di lying of' t h e b u i l d i n g component, d u r i n g loa .d ing and tile time a t which t h e damage had o c c u r r e d .

F'or c a s e s where d u r i n g i n s p e c t i o n 01. i n t h e d e s c r i p t i o n o f t h e damage no f u r t h e r d i r e c t i v e s cou1.d be o b t a i n e d f o r t h e d e t e r - minat , icn o f t h e r e q u i r e d c o e f f i c i e n t s , e x p e r i e n c e from o t h e r s m a l l e r b u i l d i n g corctponents was c a l l e d upon. F o r example , t h e d u r a t i o n o f s h o r i n g o f an apartnierlt s l a b vras assumed t o be two weeks as a n a v e r a g e . U s u a l l y , t h e water / 'cement r a t i o o f t h e c o n c r e t e was r e c o n s t i t u t e d from t h e a t t a i n e d c o n c r e t e s t r e n g t h by assuming 300 kp/m3 cement c o n t e n t .

7 . 2 C a l c u l a t i o n of t h e Te rmina l D e f l e c t i o n V a l u e s --------------------------------------------- The d e f l e c t i o n compr i se s an e l a s t l c and a p l a s t i c

component. P a r t o f t h e s e d e f o r m a t i o n s o c c u r immed ia t e ly upon a p p l i c a t i o n o f t h e l o a d ; t h e r ema inde r i s t ime-dependen t . The c a l c u l a t i o n o f t h e t h e o r e t i c a l d e i ' l e c t i o n was c a r r i e d o u t f o r b o t h t h e u r ~ c r a c k e d ( S t a t e I ) and t h e c r a c k e d ( S t a t e 1 1 ) s e c t i o n . The d e p l e c t i o n which would p r ~ o b a b l y o c c u r i n an a r b i t r a r y s t a t e o f c r a c k f o r r n a t i c n was t h e n d e t e r m i n e d by i n t e r p o l a t i o n .

E l a s t i c D e f l e c t i o n :

S t a t e I: r: = e n - !I. a 2

I I E p - En

I I S t a t e 11: l1 = c ,

0 h a 2

* T r a n s l a t o r ' s Note : M a t e r i a l T e s t i n g L a b o r a t o r y

* * kp = k i l o pond = k i l o gram f o r c e

The c o e f f i c i e n t c depends on t h e s t r u c t u r a l s y s t e m , t h e l o a d d i s t r i b u t i o n , and t h e v a r i a t i o n o f t h e moments o f i n e r t i a . The v a l u e f o r c was d e t e r m i n e d from t a b l e s o f well-known books on s t a t i c s . The moment o f i n e r t i a ( I ) was d e t e r m i n e d t a k i n g i n t o a c c o u n t t h e f a c t o r n f o r s t e e l i n s e r t s . I n S t a t e I1 t h e d e f o r m a t i o n of t h e s t e e l was d e t e r m i n e d by c o n s i d e r i n g t h e p a r t i c i p a t i o n o f t h e c o n c r e t e between t h e c r a c k s ( s e e Ref . l 7 ) .

I n c r e a s e i n D e f l e c t i o n due t o Creep f k and S h r i n k a g e f s of t h e c o n c r e t e :

S t a t e I : 1 - I f k - n~ ' @ ' f o

I I S t a t e 11: f i l -

- ~ I I @ ' f o

The v a l u e s n and s r e p r e s e n t c u r v a t u r e c o e f f i c i e n t s

which encompass t h e r e s i s t a n c e t o d e f l e c t i o n due t o t h e s t e e l i n s e r t s and

t h e r e s u l t i n g s t r e s s r e d i s t r i b u t i o n . They were d e r i v e d i n R e f . 3 .

7 . 3 Magnitude o f D e f l e c t i o n s Which I n i t i a t e d Damage -- .......................................... -

P a r t i c u l a r c a r e was t a k e n i n d e t e r m i n i n g t h e magn i tudes o f t h e d e f l e c t i o n s a t which damage o c c u r r e d . I n a d d i t i o n t o t h e g e n e r a l c o e f f i c i e n t s l i s t e d i n S e c t i o n 7 . 1 , f u r t h e r d a t a c o n c e r n i n g t h e ch rono logy o f t h e b u i l d i n g c o n s t r u c t i o n , t h e t y p e o f damage, and t h e t i m e o f f i r s t o b s e r v a t i o n o f damage had t o b e c o l l e c t e d . The c a l c u l a t i o n p r o c e d u r e w i l l be shown b r i e f l y i n t h e f o l l o w i n g two examples .

( a ) The c r a c k s o f a s u p p o r t e d p a r t i t i o n w a l l a r i s e on ly f rom t h o s e d e f l e c t i o n components which o c c u r r e d a f t e r t h e e r e c t i o n o f t h e w a l l and a f t e r t h e a p p l i c a t i o n o f t h e i n t e r i o r p l a s t e r f i n i s h . These d e f l e c t i o n components depend on t h e i n c r e a s e o f c r e e p and s h r i n k a g e d e f o r m a t i o n o f t h e c o n c r e t e , on t h e a d d i t i o n a l l o a d i n g which became e f f e c t i v e s u b s e q u e n t l y ( e . g . a p p l i c a t i o n o f t h e f l o o r c o v e r i n g , t h e c e i l i n g f i n i s h , o r t h e l i v e l o a d ) , and on t h e e x t e n t o f e x i s t e n c e o f S t a t e 11. F o r c a s e s where no more a c c u r a t e i n f o r m a t i o n c o u l d be g a t h e r e d from documents , i t was assumed t h a t t h e pe rmanen t ly a c t i n g l i v e - l o a d component became e f f e c t - i v e o n l y a p p r o x i m a t e l y f i v e months a f t e r t h e p a r t i t i o n w a l l

p l a s t e r i n g had been comple t ed .

I n S e c t i o n 9 a sample c a l c u l a t i o n i s pe r fo rmed f o r d e t e r m i n a t i o n o f t h e d e f l e c t i o n which i n i t i a t e d t h e damage.

( b ) I n t h e c a s e o f a s a g g i n g s l a b , t h e a c t u a l l y measured d e f l e c t i o n i s i t s e l f t h e s o u g h t - a f t e r d e f l e c t i o n which i n i t i a t e s t h e damage, s i n c e o n l y t h i s v a l u e seemed d i s t u r b i n g t o t h e o b s e r v e r . N e v e r t h e l e s s , even i n t h e s e

c a s e s t h e t h e o r e t i c a l d e f l e c t i o n was c a l c u l a t e d i n o r d e r t o check whe the r t h e d e f l e c t i o n of t h e s l a b was r e a l l y t h e s o l e c a u s e .

7 . 4 C o e f f i c i e n t s o f Deformat ion Which Were C a l c u l a t e d S i m u l t ~ a n e o u s l ~ ----------------------------------------------------------------- With t h e 2 e f l e c t i o n -------------------

I n o ~ d e r t o f i n d t h e r e 1 e t i o : l s h i p s which gove rn t h e o c c u r r e n c e o f a p a r t i c u l - a r i n s t a r c e o f damage, t h e r e l a t i v e d e f l e c t i o n f / E , t h e maximum c u r v a t u r e max. l / ' p , t h e l a r g e s t end r o t a t i o n o f t h e s u p p o r t s , max . t h e l a r g e s t a n g l e of t h e t a n g e n t s t o t h e n e u t r a l ax:;s, max. tan!tii9alrd t h e f i n a l c r a c k open ing d were c a l c u l ~ t e d , i n a d d i t i o n t o t h e d e f l e c t i o n fSch ( s e e T a b l e s j n t h e Appendix, columns 2 1 - 2 5 ) .

8 . FACTORS RESPONSlBLE FOR TdE OCCURRENCE OF DEFLECTION DAMAGE

8 . 1 T h e o r e t i c a l l y P o s z i b l e S o u r c e s o f Dan,age --------------------..---.----...--------- -

A s h a s been r e p e a t e d l y i n d i c a t e d , t h e German Re ln foyced Concre t e Code C I N 1045 c o n t a i n e d v a r i o u s deficiencies which e x p l z i n some of t h e nlentloned t y p e s of d e f l e c t i o n damage. Such d e f i c i e n c i e s (Nos. I - V i n column 17 o f t h e t a b l e s i n t h e Appendix) i n c l u d e e s p e c i a l l y t h e f a c t t h a t e x c e s s i v e d e f l e c t i o n s l e n d e r n e s s r a t i o s were p e r m i t t e d f o r two-way r e i n f o r c e d p l a t e s . Another l a y i n t h e f a u l t y b a s j s used f o r c a l c u i a t i o n of d e f l e c t i o n s . ? ' h i s y i e l d e d e x c e s s i v e l y small . v a l u e s aild t h e r e b y gave t h e d e s i g n e r t h e i . l l u s i o n o f t o o f a v o u r a b l e a d e f o r n a t i o n behav iou ro f r e i n f o r c e d c o n c r e t e b u l l d i n g components . The d e f l e c t i o n was c a l c u l a t e d f o r a n unc racked s e c t i o n w i t h t h e same modulus o f e l a s t i c i t y c f c o n c r e t e fo? a l l c o n c r e t e s t r e n g t h s . l 'he t h i r d d e f i c i e n c y l a y i r i t h e f a i l u r e t o r e q u i r e a d e q u a t e c o n s i d e r a t i o n o f t h e c r e e p and s h r i n k a g e d e f o r n a t i o n s o r t h e c o n c r e t e . T h i s may c e l l be because s u f f i c i e n t i r ) fo r roa t ion on t h e e f f e c t s o f c r e e p and s h r i n k a g e of' c v n c r e t e has on ly been accumula ted g r a d u a l l y d u r i n g t h e les t few d e c a d e s .

Also , a series of e r r o r s weye committed i n t h e s t a t i c a l c a l c u l a t i o n s . These e r r o r s (Plos. lrI t o X i n column 17 o f t h e t a b l e s i n t h e Appendix) r e s u l t e d p a r t : c u l e r l y from ' Incor rec t . assumpt!.ons c o n c e r n i n g t h e s t a + , i c sys t em, and o n l y s e c o n d a r i l y rrom l iumer ica l e r r o r s . F o r example, i t i s u s u a l l y i n a p p r o p r i a t e t o assume f u l l end r e s t r a i n t s f o r a s l a b c o n n e c t i r ~ g t o a 38 crn b r i c k w a l l o f a o n e - s t o r e y r e s i d e n t i a l bu l i l d ing . S j m i l a r l y , t h e fav0urabJ .e e f f e c t u f t o - s i o n a l s t i f f n e s s o f s imp ly upp ported two-way r e i n 3 o r c e d p l a t e s :;hould be t a k e n i n t o a c c o u n t o n l y \:hen a r a i s i n g o f t h e cor r le rs i s p r e v e n t e d e i t h e r by d e s i g n o r by s t a f 2 i c cond i t . i ons . Also , i n s u f l n i c i e : n t c o n s i ~ l e r a t i o n o f f ' ounda t ion s e t t l e m e n t can l e a d t o b1lild:ng damage, s i r ~ c e s t r e s s r e d i s t r i b u t i o n w i l l r e s u l t i n a d i f f e r e n t l o a d i n g e f f e c t o f t h e r e i n f o r c e d c o n c r e t e b u i l - d i n g components t h a n had been assumed i n t11e s t a t i c c a l c u l a t ' o n s . F i n a l l y , t h e d a n g e r o f o v e r l y f a v o u r a b l e 1oad:ng a s s u m p t i o n s must a lways b e bo rne i n mind.

A wide varie ' ;y o f caust ls o f damage a p p e a r s p o s s i . b l e d u r i n g c o n s t r u c t i o n o f t h e b u i l d i n g (Nos. X I - XV i n column 17 o f t h e t a b l e s i n t h e Appendix) . A s one o f t,he p r i n c i p a l . :;ourc:es, l n s u f f i c l e n t compressive s t r e n g t h o f c o n c r e t e may be m e i ~ t i o n e d . There a r e v a r i o u s p o s s i b l e rclasorls f'o? t h i s : u n s a t i s f a c t o r y g r a i n - s i z e d i s t r i b u t i o n , i n : j ~ f f f . c I e n t cerrient , t o o l a r g e a wat,er/cement r a t i o , f r o s t e f f e c t s , e t c .

O c c a s i o n a l l y , t o o few r e i n f o r c e m e n t s were i n s t a l l e d , c o n t r a r y t o t h e r e i n f o r c i n g s c h e d u l e s , o r t h e wrong s t e e l q u a l i t y was u s e d . Q u i t e f r e q u e n t l y t h e r e i n f o r c e m e n t was n o t l o c a t e d a t t h e s p e c i f i e d d e p t h . D e f i c i e n t form-work o r e x c e s s i v e span l e n g t h s between b a r s u p p o r t s can a l s o c a u s e d e t r i m e n t a l d e f l e c t i o n s . W e may a l s o men t ion i n s u f f i c i e n t s l a b t h i c k n e s s , o r a t o o na r rowly formed s o l i d c o n c r e t e edge s t r i p o f a r i b b e d s l a b .

F i n a l l y , e r r o r s had been committed a l s o i n t h e d e s i g n phase o f t h e b u i l d i n g components . Such an e r r o r (Nos. X V I - X X i n column 17 o f t h e t a b l e s i n t h e Appendix) o c c u r s , f o r i n s t a n c e , when no r e i n f o r c e - ment h a s been p r o v i d e d f o r t h e r e s i s t a n c e o f p o s s i b l e r e s t r a i n t moments. T h i s r e s u l t s i n l a r g e c r a c k s i n t h e c o n c r e t e t e n s i o n zone . Very f r e - q u e n t l y t h e d e f o r m a t i o n s f o r t h e assumed s t r u c t u r a l a c t i o n o f t h e re- i n f o r c e d c o n c r e t e b u i l d i n g components c o u l d n o t t a k e p l a c e w i t h o u t s t r e s s i n g a d j o i n i n g b u i l d i n g components f a r beyond t h e i r l o a d c a p a c i t y . I n t h i s c o n n e c t i o n we may ment ion t h e h o r i z o n t a l c r a c k s i n t h e e x t e r i o r p l a s t e r which have come a b o u t f rom t h e r o t a t i o n o f t h e edge s u p p o r t s o f r e i n f o r c e d c o n c r e t e s l a b s . The s u p p o r t i n g o f r e i n f o r c e d c o n c r e t e components on p l a t e g l a s s windows must a l s o be viewed a s a d e s i g n e r r o r and s i m i l a r l y , t h e u n i n t e n t i o n a l s u p p o r t i n g o f s l a b s on p a r t i t i o n w a l l s o r aluminum c u r t a i n w a l l s .

A s p e c i a l damage c a u s e i s t h a t o f a p a r t i t i o n w a l l r e s t i n g on t h e f l e x i b l e s u p p o r t p r o v i d e d by a r e i n f o r c e d c o n c r e t e s l a b . P a r t - i t i o n w a l l s were a l s o s u p p o r t e d on t h e s l a b s i n fo rmer days when t h e s l a b s were ma in ly s u p p o r t e d by wood and s t e e l g i r d e r s . However, t h e w a l l s d i d n o t c r a c k t o t h e same e x t e n t a s t h e y do today. . The w a l l s mere ly had t o r e s i s t changes i n t h e e l a s t i c d e f o r m a t i o n s caused by t h e v a r i a b l e l i v e l o a d . But t h e c o n c r e t e s l a b s commonly u s e d t o d a y a r e s u b j e c t t o s u b s t a n t i a l t ime-dependent c r e e p and s h r i n k a g e d e f o r m a t i o n s . Fu r the rmore , g r e a t e r s p a n l e n g t h s a r e chosen . The p a r t i t i o n w a l l c a n n o t accommodate such l a r g e d e f o r m a t i o n s and c o n s e q u e n t l y i t c r a c k s . T h i s s p e c i a l c a u s e o f damage was i n c l u d e d among t h e d e s i g n e r r o r s , a l t h o u g h s t r i c t l y s p e a k i n g , g i v e n t h e s t a t e o f knowledge a t t h e t i m e i t canno t p r o p e r l y be c a l l e d a n e r r o r .

8 . 2 ACTUAL CAUZES OF DAMAGE

F i ~ u r e 9 g i v e s a s u r v e y o f t h e a c t u a l c a u s e s o f damage, a r r i v e d a t t h r o u i h t h e un i fo rm a n a l y s i s o f t h e r e p o r t s r e c e i v e d . The above-mentioned t h e o r e t i c a l l y p l a u s i b l e c a u s e s a r e p l o t t e d on t h e a b s c i s s a , w i t h a r e f i n e d g r i d i n t h e o r d e r o f t h e numbering scheme, w h i l e t h e f r e q u e n c y o f t h e i r o c c u r r e n c e i s p l o t t e d a l o n g t h e o r d i n a t e .

I t became a p p a r e n t t h a t most c a s e s o f d e f l e c t i o n damage c o u l d be t r a c e d t o e x c e s s i v e l y f l e x i b l e p a r t i t i o n w a l l s u p p o r t (XIX). Very f r e q u e n t l y t h e damage o c c u r r e d a s a consequence o f e x c e e d i n g t h e p e r m i s s i b l e d e f l e c t i o n s l e n d e r n e s s r a t i o o f t h e r e i n f o r c e d c o n c r e t e s u p p o r t member ( I ) . The s o l i d p a r t o f column I i n t h e h i s t o g r a m r e p r e s e n t s a l l t h e c a s e s which were due t o a v i o l a t i o n o f t h e p r o v i s i o n s i n e f f e c t a t t h a t t i m e ; t h e dashed p o r t i o n refers o n l y t o c a s e s where t h e d e f l e c t i o n s l e n d e r n e s s r a t i o was g r e a t e r t h a n 35. Thus t h e d a s h e d p a r t a g a i n p o i n t s t o t h e p a r t i c u l a r s u s c e p t i b i l i t y t o damage o f two-way r e i n f o r c e d s l a b p a t t e r n s .

The o t h e r c a u s e s o f damage a r e much less prominent i n compar ison t o t h e s e two s o u r c e s o f e r r o r s . The n e x t i m p o r t a n t c a t e g o r y i s t h a t o f i n a d e q u a t e c o n c r e t e q u a l i t y ( X I ) . A s i m i l a r , i f

n o t g r e a t e r , i m p o r t a n c e must be a s c r i b e d t c r e i n f c l r c e r ~ e n t s l o c a t e d a t t o o g r e a t a d e p t h ( X l I I ) . The f r e q u e n c y shown i n F i g . 9 p r o b a b l y i p d i c a t e d t o o f s . v c u r a b l e a r he ! . a t i onsh ip , s i n c e t h e a c t u a l d e p t h o f r e i n f o r c e m e n t was r13t d e t e r m i n e d i n a j l c a s e s . F r e q u e n t l y i t was n o t d e s i r a b l e t o c a r r y ou t t h e c o m p r e h e n s i v e i n v e s t i g a t i ~ n t h a t would be neecled f o r t h l s , which n o r e o v e r ~ o u l d o n l y l e a d t o f ~ r t h e r uanage . However, e x p e r i e n c e f rom o n - s i t e i n v e s t i g a t i . o r i s clurling c o n s t r u c t i o n i n d i c a t e s tk ia t t h e t o p r e i r ~ f o r c e r n e n t f r e q u e n t l y g e t s p u s h e d down d u r i n g t h e p l a c i n g o f c o n c r e t e . T h i s e x p e r i e n c e i s r e p e a t e d l y c o n f i r m e d , d e s p i t e f r ~ q u e n t g r o t , e s t e t i o n s on t h e p a r t o f s u p e r i n t e n d e n t s , f o r e m e n , and o t h e r s i n v o l v e c i i n t t ~ e c o n s t r u c t i c : n , r e g a r d i n g t t : e r e l i a b i l i t y o f t f l e i r c a r e f u l wcrkmanshj-p .

Srince t.he o t h e r c .auses o f damage car1 a l s o be j u d g e d fr3or.r t h i s p r ~ i n t o f v i e w , t h e s l i g h t d i f f e r e n c e s i n f r e q u e n c y o f t h e r e m i i i n i r i ~ causes nay be d i s1 , ega rded f o r t h e most p a r t .

I t i s i r i s t r ~ ~ c t i v e , however , t o c o n s i d e r a g r o u p i n g o f frequencies s j n c e j t i n d i c a t e s t h e r e s p o n s i b i l i t y o f t h e v a r l o u s p e r s o n n e l c a t t : g o r i e s p a r t i c i p a t i n g j n b u l - l d i n g c o n s t r u c t i c n . The f o u r majn g r o u p s o f c a u s e s which we e e t z b l i s h e d showed t h e f o l l o v r i n g f r e q u e n c i e s :

d e s ip;n e r r o r s 1 3 7 t i m e s s i z e d e f i c i e n c i e s 76 times e r r o r s i n viorkn;anship 56 t i m e s c a l c u l a t , i o n e r r o r s 33 t i m e s

F r e ~ ~ u e n t l y , F o r e t h a n one c a u s e c o n t r i b u t . e d t o t h e same damage. Here a g a i n , t h e l i m i t . a t i o n o f s t a t i s t i c a l e v i d e n c e s h o u l d n o t b e o v e r l o o k e d .

8 . 3 Conncctic:ri Bet,weer~ O r i g i n a n d Type o f Damage --- ---- ---.-------- -.----------

A more r e l i a b l e i r ~ d i c a t i o n i s gj-ven i n T a b l e 1 which shorrs t h e f r e q u e n c y d i s t r l i b u t i o n o f t h o s e damage c a s e s i n which o n l y one s i n g l e c a u s e was r e s p o n s i t ~ l e . T h i s s p e c i a l p r e s e n t a t i c n shows t h a t i r l 2 1 c a s e s p a r t i t i o n w a l l c r a c k s were c a u s e d m e r e l y by t h e f l e x i b l e s u p p o r t o f t h e \:all e v e n where t h e s l e n d e r n e s s r a t i o s were s m a l l e r t h a n 1 5 . A cii : ; turkJir .g s a g r e s u l t e d m a i n l y frorn a n e x c e s s i v e s l e n t i e r n e s s r ~ ~ t i o C J r f r om p o o r l y rllade c o n c r e t e . C r a c k s i r a r e i n f o r c e d c o n c r e t e g i r d e r were n o t . i c e d m a i n l y when r e i n f o r c e n e n t b-as a b s e n t o r t o o s p a r s e . Damagc- r e s u l t i n g frorn s u p p o r t r c l t a t i o n s c a n e v i d e n t l y be a s c r i b e d e x c l u s i v e l y t o d c s i g n e r r c n r s . The c a u s e s o f p l a s t e r o r f i n i s h i n g damage i r ves t . i ga t , ed i n . t h i s a n a l y s i s , as might. b e e x p e c t e d , r e s u l t s o l e l y f r om e x c e s s i v e d e f 1 e c t i . o n s l e n d e r n e s s , ora more p r e c i s e l y , f r om e x c e s s i v e c l e f l e c t i c n . F j - n a l l y , i n t h e l a s t l i n e d e s i g n e r r o r s a l o n e a c c o u n t f o r the damage i n two mcre i n s t a n c e s . I n b o t h c a s e s v e r t i c a l de fo rma t ion : ? a p p e a r e d a t a n e x p a n s i o n j o i r i t b e c a u s e t h e d i f f e r e n t i a l d e f o r m a t i o n s o f t h e two n e i g h b o u r i n g c o n c r e t e components had n o t t ' e e n a d e q u a t e l y c o r i s i d e r e d .

9. EVALTJATTON O F F'ARTITION VIALL DAMAGE

9 . 1 Typee o f P a r t i t . i o n \ : a l l Lamage Observed - - - - - - - - - - - . - - - - . - - - . - . - - - - --------

A c c o r d i n g t o S e c t i o n 5 t h e f o l l o w i n g t y p e s a r e d e s i g n a t e d as p a r s t i t i . o n w p - 1 1 damage : " P a r t i t i o n w a l l c r a c k s , g a p s be tween wal l and f l o o r , ar:d janmed door^ o r w~.ndows". The 1 a . t t e r t y p e o f damage o c c u r r e d o n l y f i v e t i m e s , a n d w i l l n o t be c o n s i d e r e d

h e r e i n a f t e r . The majn emphas ls w i l l f ' a l l r a t h e r on p a r t i t i o n w a l l c r a c k s , which c a t e g o r y we have e x t e n d e d t o i n c l u d e t h e g a p s between w a l l and f l o o r .

Normal ly , t h e c r a c k s o c c u r r e d w i t h i n t h e w a l l a r e a a s s h e a r c r a c k s a t 4 5 O , o r h o r i z o n t a l l y a s t e n s i o n c r a c k s a l o n g a m o r t a r j o i n t o f t h e b r i c k w o r k . Sometir~ies , however , t h e y a l s o a p p e a r e d v e r t i c a l l y i n t h e form OF' f l e x u r a l c r a c k s . H o r i z , o n t a l and v e r t i c a l c r a c k s a l s o o c c u r r e d a s a consequence o f r o t a t i o n s o f whole w a l l p l a t e s , p a r t i c u l a r l y a t t h e j o i n t between w a l l and c e i l i n g , a s w e l l as a t t h e j o i n t between two w a l l s m e e t i n g a t r i g h t a n g l e s .

The v a r i o u s t y p e s o f c r a c k s a r i s e from v a r j o u s s t r e s s c o n d i t i o n s . It i s t h e r e f o r e a p p r o p r i a t e t o group them from t h i s p o i n t o f v2ew.

With small s p a n s a n a r c h i n g a c t i o n a p p a r e n t l y d e v e l o p s w i t h i n t h e b r i ckwork . The s t resses i n t h e b r i ckwork are s t i l l small enough s o t h a t no c r a c k s o c c u r . The w a l l c a r r i e s i t s own w e i g h t , whereas t h e r e i n f o r c e d c o n c r e t e s la .b , which o r i g i n a l l y was t o have suppo1.t e d t h e w a l l , i s d e f l e c t e d downwards. Between t h e wall an3 t h e f l o o r a g a p l n g ci2ack r e s u l t s (see F i g . 1 0 a ) whose wid th depends on t h e bend ing f l e x i b i l i t y o f t l l e r e i n f o r c e d c o n c r e t e s u p p o r t membel*.

'The a r c h w z t h i n t h e l o a d - - b e a r i n g wall f i n d s i t s r e a c t i o n s n o t o n l y a t t h e s l a b s u p p o r t s b u t a l s o a t an immovable s i d e wall ( F i g . l o b ) o r i n t h e v i c i n i t y o f i n f l e c t i o n p o i n t s o f a r e s t r a i n e d s l a b ( P i g . 1 0 c ) . Thiz c a r r y i n g c a p a c i t y of t h e pa id t i t3 .0n w a l l h a s been o b s e r v e d up t o an e q u i v a l e n t s p a n l e n g t h of a p p r o x i m a t e l y ti = 7 . 0 m .

I n c a n t j l e v e r c o n s t r u c t i o n which s u p p o l a t s b r i ckwork , l a r g e gaps between t h e b r i ckwork arld t h e suppor - t i ng r e i n f o r c e d c o n c r e t e s l a b have been obse rved r e p e a t e d l y [ F i g . 1 0 ( d ) ] . The gap i s n o t due t o a r c h i n g , bu t r a t h e r due t o t h e bend ing c a p a c i t y of t h e w a l l . The r a t i o o f c a r ~ t i l e v e r l e n g t h t o t h e w a l l h e i g h t i s s t i l l s m a l l enough s o t h a t t h e bend ing t e n s i l e s t r e n g t h o f t h e br ick icork a t t h e r e s t r a i n e d s e c t i o n llas n o t y e t been exceeded .

F r e q u e n t l y , t h e a r c h i r ~ g a c t i o n I n t h e p a r t i t i o n w a l l i s d i s t u r b e d by a door o p e n i n g s j - t u a t e d a t an u n f a v o u r a b l e l o c a t i o n . The span o f t h e p a r t i t i o n w a l l shown i n F i g . I l ( e ) i s t o o la17ge f o r t h e r ema in ing c r o s s - s e c t i o n a l h e i g h t above t,he d o o r . U n d e ~ > s t a n d a b l y , t h e two w a l l s e c t i o n s sheam a t t h e corr1el.s of t h e d o o r o p e n i n g . The c r a c k s s t a r t h o r j - z o n t a l l y due t o weokenlng by t h e s u p p o r t j o i n t and t h e n c o n t i r ~ u e t o p r o p a g a t e upwards. The o r i g i n a l w a l l p l a t e , f o r a l l p r a c t i c a l pul-poses, i s d i v l d e d i n t o two p l a t e componenl;~ which w i l l f o l l o w t h e s l a b d e f l e c t i o n a lmos t w i t h o u t r e s i s t a n c e . C h a r a c t e r i s t i c o f t h i s s u p p o r t c o n d i t i o n are h o r i z o n t a l c r a c k s between w a l l and c e i l i n g , a n d v e r l i i c a l c r a c k s between p a r t i t f on w a l l arid e x t e r i o r wai 1.

Such w a l l r o t a t i o n s t e n d t o o c c u r p a r t : c u l s r l y whenever a ha l lway i n t h e c e n t r e o f a b u i l d i n g e x c l u d e s a r c h i n g a c t j . o n [ P i g . 11 ( f ) I .

The h o r i z o n t a l c r a c k s between t h e w a l l and c e i l i n g were a l s o n o t i c e d i n p a r t i t i o n w a l l s which were l o c a t e d normal t o t h e

r e i n f o r c i n g d i r e c t i o n o r t h e r e i n f o r c e d c o n c r e t e s l a b [ F i g . l l ( g ) ] . I n 1,his c a s e , t h e w a l l s imp ly c r a c k s because i t , d e f l e c t s downwards w i t h t h e s a g g i n g r e i n f o r c e d c o n c r e t e s1a.b. A p r e r e q u i s i t e i s a s m a l l e r d e f l e c t i o n magni tude of t h e c e i l i n g above tlre w a l l .

With i n c r e a s i r - g s p a n s t h e s t ~ * e s s e s w i t h i n t h e p a r t i t i o n w a l l grow. Cracks i n c l i n e d a t app rox ima te ly 4 5 O o c c u r i n t h e v 2 c i n i t y o f t h e s u p p o r t s . So f a r t h e middle p o r t i o n o f t h e w a l l between t h e i r ~ c l i n e d c r a c k s r ema ins uncraclced. He1.e a l s o a r c h i n g e x i s t s by means of which t h e middle por . t ion o f t h e w a l l car! s u p p o r t l t s e l f [Fj.g. 1 2 ( n ) 1. If e v e n f o r t h i s i r - n e r a r c h t h e sFan l e n g t h becomes t o o g r e a t , a h o r i z o n t a l c r a c k a l o n g t h e m o r t a r j o i n t s can o c c u r [ F i g . 1 2 ( i ) 1. U s u a l l y , however , t h e w a l l i s weakened i n v a r i o u s ways by does o p e n i n g s , r e c e s z e s f o r h e a t i n g e l e m e n t s , e t c . Consequen t ly c r a c k f o r m a t i o n s o f q u i t e vary2ng forms o c c u r , which o f t e n p e r m i t one t o r e c o g n i z e unmis tak- a b l e s h e a r deformat ior i s o f t h e w a l l . But sometimes a l s o a r o t a t i o n of l i m i t e d w a l l s e c t i o n s o r a r e s t , r a i r . t i n n e i g h b o u r i n g s i d e w a l l s can be i d e n t i f ' i e d [ F i g . 1 2 C k ) l .

F i n a l l y , i n p a r t i t i o n w a l l s numerous c o m p a r a t i v e l y c l o s e l y s p a c e d c r a c k s can o c c u r [ P i g . 1 3 ( 1 ) 1 . The p a t h o f t h e i n d i v i d u a l c r a c k s i s s i m l l a r t o t h a t i n a r e i r ~ f o r c e d c o n c r e t e g i r d e r . It may t h e r e - f o r e be assumed t h a t a p a r t i t i o n w a l l t h a t h a s c r a c k e d i n t h i s manner , b e s i d e s s u p p o r t i n g i t s own w e i g h t , i s main ly s u b j e c t e d t o e x t e r n a l l o a d i n g , e . g . by u n 5 . n t e n t i o n a l l y s u p p o r t i n g t h e o v e r l y i n g r e i n f o r c e d c o n c r e t e s l a b .

The e x c e e d i n g o f t h e bt2nding t e n s i l e s t r e n g t h o f t h e b r j ckwork i r i a c a r ~ t i l e v e r e d w a l l p l a t e can a l s o l e a d t o v e r t i c a l c r a c k s i n t h e v i c i n i t y o f t h e r e s t r a i n e d s u p p o r t [ F i g . 1 3 ( m ) ] . ?.he w a l l r o t a t e s hy a n amount e q u a l t o t h e end : l o t a t i o n o f t h e can1 ; i l eve red r e i n f o r c e d c o n c r e t e p l a t e and i n t h i s way accommodates i t s e l f t o t h e d e f l e c t i o n o f t h e s u p p o r t i n g member.

9 . 2 L imi t ir ,g Vaj u e s f o r t h e I n i t i a t , i o n o f P a r t i t l .on Wall Cracks ---. --.-.--- ----- ------- --

It secms r e a s o n a b l e t o d e t e r m i n e t,he i n i t i a . t i o r 1 o f p a r t i t i o n w a l l c r a c k s f r ~ m t h e bend ing f l e x i b i l i t y of t h e p a r t i c i p a t i n g reir.forc:ed c o n c r e t e s u p p o r t members. S i r ~ c e t h e c a r r y i r ~ g c a p a c i t y o f t h e p a r t i t i o n w a l l C-epends mhinly on t h e s p a n l e n g t h , t h e r e p o r t e d p a r t i t i o n wa l l damage h a s been p l o t t e d i n F i g . 1 4 as a f u n c t i o n o f t h e b e n d i n g s l e n d e r n e s s and t h e e q u . i v a i e n t span l e n g t h . I n o r d e r t o f a c i l i t a t e t h e e v a l u a t i o n o f t h e r e s u l t i n g mass o f p o i n t s , t h e v a r i o u s t y p e s o f p a r t i t i o n w a l l c r a c k s have been d e s i g n a t e d by d i f f e r e n t symbols .

An i m p o r t a n t c o n c l u s i o r ~ t h a t may be drawn fraom t h i s p r e s e n t a t 3 o n i e that: no damage o c c u r ~ . e d i n t h e v i c i n i t y o f s h o r t span l e n g t h s a s w e l l a s I n t h e v i c l n i t y o f s m a l l b e n d i n g s l e n d e r n e s s e s . T h i s l e a d s t o t h e e x p e c t a t i o n t h a t i t may be p o s s i b l e t o s t a t e a l i m i t i n g v a l u e f o r t h e p r e v e n t i c . n of clamage.

The s c a t t e r o f t h e damage p o i n t s , however , i s s o g r e a t t h a t e s t a b l i s h m e n t of a l o w e r l i m i t i n g c u r v e f o r t h e s e r i e s o f p o i n t s w i l l a t f i r s t g l a n c e a p p e a r q u i t e a i ? b i t r a r y . On t h e o t h e r hand , none

of t h e f o u r d i f f e r e n t t y p e s o f p a r t i t i o n wal.1 c r a c k s r e v e a l any intrinsic r e g u l a r i t i e s .

A s a consequence we a r e f a c e d w i t h t h e q u e s t i o n of how t h e wide s c a t t e r o f p c i n t s had a r i s e n . S u r e l y one reasort may be Sound i n t h e p r o p e r t i e s o f tihe p a r t i t i i o n w a l l i t s e l f . A s a l r e a d y men t ioned , g r e a t d i f f e r e n c e s o c c u r r e d because of i r r e g u l a r l y spaced open:Lngs and because o f u n i n t e n t i o n a l r e s t r a i n t s o f s i d e w a l l s . A l so , s h r i n k a g e s t r e s s c : ~ w i t h i n 1;he b r i ckwork r increase t h e u n c e r t a i n f y o f i n i t i a t i o n o f t h e f i r s t c r ac l r s . The brickwork i t s e l f i s nfit i s o t r ' o p i c . S u b s t a n t i a l d i f f e r e n c e s e x i s t i n t h e m a t e l a i a l r i g i d i t i e s between t h e j o i n t s and t h e b r i c k s . Fu r the rmore , t h e w a l l s invest .>igat ,ed c o n s i s t o f qui1,e d i f ' f e r e n t m z t e r i a l s w i t h v a r y i n g r i g i d i t i e s .

A second c a u s e may l i e i n t h e b e h a v i o u r o f t h e support:,ing r+e in f o r c e d c o n c r e t e member. A s a l r e a d y merltioned, t h e bend ing s l e n d e r n e s s p i o t t e d on t h e o r d i n a t e i s o n l y a v e r y rough i n d i c a t i o n o f t h e d e f l e c t i o n b e h a v i o u r . N e i t h e r t h e q u a l i t y o f c o n c r e t e , t h e amount o f r e i n f o r c i n g , n o r t h e c r e e p and s h r i n k a g e b e h a v l o u r o f t h e c o n c r e t e a r e i n c l ~ . d e d . Nor a r e t h e v a r y i n g manufactur3.ng cond i l , i ons o f t h e b u i l d i n g componr?nt n o r t h e consequences o f a rcisplaceci r e i n f o r c e m e n t t a k e n i n t o a c c o u n t .

A l l . o f t h e s e n e g l e c t e d i n f ' u e n c e s must n e c e s s a r i l y l e a d t o a wide s c a t t e r o f t h e p l o t t e d damage p o i n t s . I n F i g . 15 , t h e r e f o r e , t h e bend ing s l e n d e r n e s s o r d i n a t e h a s been r e p l a c e d by t h e c a l c u l a t e d d e f l e c t i o n r a t i o fgch f o r t h e i n i t i a t i o n o f damage. Even s o t h e s c a t t e r c o u l d n o t be substantially r e d u c e d . P l o t s o b t a i n e d w i t h o t h e r d e f o r m a t i o n a l q u a n t i t i e s , e . g. t h e m~ximum i n c l i n a t i o n o f t h e bend ing l i n e o r t h e maximum c u r v a t u r e of a g i r d e r , which a r e n o t p r e s e n t e d h e r e i n , b rough t no i m p ~ ~ o v e m e n t . E v i d e n t l y , t h e above-narrled d i f fe r lences i n t h e b e h a v i o u r o f t h e p a r t i t i o n w a l l i t s e l f a r e o r p a r t i c u l a r l y g r e a t i n f l u e n c e .

From t h e dependence o f t h e r e l a t i v e c l e f ' l e c t ion on t h e e q u i v a l e n t span l e n g t h t i , shown i n F i g . 1 5 , i t might be conc luded t h a t r i s k o f p a r t i t i o n w a l l c r a c k i n g a o e s n o t depend on t h e span l e n g t h b u t i s de te rmined o n l y by t h e c o n s t a n t m a g r ~ i t u d e o f 1,he r e l a t j - v e d e f l e c t i o n . The a b s o l u t e magnitude o f t h e p e r m i s s i b l e d e f l e c t i o n f o r c r a c k - - f r e e c o n d i t i o n s would t h u s be o b t a i n e d from t h e o b s e r v e d lower l i m i t i n g v a l u e o f fSch = 1/1000 = 0 .001 .

Fo r t h e p r o p e r e v a l u a t i o r ~ o f t h e damage p o i n t s i t i s n e c e s s a r y , t h e r e f o r e , t o i.eso:.t t o f u r t h e r t h e o r e t i c a l c o n s i d e r a t l o n s . It msy be assumed t h a t t h e p a ? - - t i t i o n w a l l removes i t s e l f o n l y g r a d u a l l y f rom t h e s u p p o r t i n g I - e i n f o r c e d c o n c r e t e nrember. S i n c e i n i t l a l l y o n l y t h e middle r e g i o n o f t h e w a l l i s s imp ly s u p p o r t e d , t h e beam a c t i o n which t e n d s toward c r a c k f o r m a t i o n o c c u r s l a t e r . T h i s g r a d u a l f o r m a t i o n of s t ress i n t h e p a r t i t i o n w a l l i s a c c e n t u a t e d by t h e c r e e p de fo rn i a t ions i n t h e rnort a r j o i n t s o f t h e brickwollk. T h e o r e t i c a l l y , t h e r e f o i d e , a c e r t a i n damage-free r e g i o n a l r e a d y e x i s t s b e f o r e a p a r t i t i o n w a l l c r a c k s . S i m i l a r l y , i t nay be assumed t h a t a c e r t a i n gap between w a l l and f l o o r i s masked by t h e b a s e b o a r d . The amount o f d e f l e c t i o n , t h e r e - f o r e , i s riot y e t r e g i s t e r e d a s a damage.

A c o n s t a n t v a l u e o f t h e d e f l e c t i o n which i n i t i a t e s damage can t h e r e f o r e n o t be c o n s j d e r e d s a t , i s f a c t o r y , p a r t i c u l a r l y s l n c e t h e t o t a l i t y o f p o i n t s c l e a r l y shows a dependence on t h e e q u i v a l e n t , span l e n g t h . More p l a u s i b l e i s t h e cu rve d-awn i n F i g . 1 5 which obeys

The f o u r damage p o i n t s which l i e below t h i s l i m i t i n g c u r v e ;n F i g . 1 5 app ly r e s p e c t i v e l y t o a s e l f - s u p p o r t i n g w a l l , a w a l l r o t a t i o n , and two c a s e s o f c r a c k f o r m z t i o n which cou ld n o t be e x p l a i n e d on t h e b a s i s o f t h e damage d e s c r i p t i o n . The wice s c a t t e r o f t h e r e m a i n i n g p o i n t s may be asc : r ibed t o a n i n a b i l i t y t o make t h e T ~ a l u e s of t h e d e f o r n ~ a t i o n a l cons1,ants f i t t h e a c t u a i c o n d i t i o n s . The c a l c u l a t i o n i s i n p a r t ex t r eme ly s e n s i t . i v e ( s e e S e c t l o n 9 . 3 ) .

The above c o n d i t i o n shows t h a t t h e d e f l e c t i o n which i n i t i a t e s damkge depends on t h e s t r u c t u r a l . c o n f i g u r a t i o n . If' t h e e q u a t i o n i s s o l v e d f o r f S c h , we g e t t h e d e f l e c t i o n c o e f f i c i e n t l / k (cm) which i s a f u n c t i o n o f t h e c o n f i g u r a t i o n f a c t o r k . I n t h e c a s e o f a s imp ly s u p p o r t e d g i r d e r , f o r example, t h e r e i s no need t o f e a r c r a c k i n g o f t h e suppo- ted w a l l at d e f l e c t i o n s unde r 1 . 0 cm; i n t h e c a s e o f a g i r d e r r e s t r a i n e d a t one e n d , unde r 1 / @ . 6 = 1 . 2 5 cm; and a g i r d e r r e s t r a i n e d at b o t h e n d s , under 1 / 0 . 6 = 1 . 6 7 cm.

The d e t e r n ~ i n a t i o n o f t h e d e f l e c t i o n t h r e s h o l d f o r da.mage, however, u s u a l l y i r ~ v o l v e s a s u b s t a r ~ t i a l e f f o r t , a.nd y e t t h e r e s u l t s a r e modest , s i n c e a wide s c a t t e r s t i l l r e m a i n s . It t h u s seems j u s t i f i e d t o t r e a t t h e d e f l e c t i o n b e h a v i o u r oi' r e i n f o r c e d c o n c r e t e s u p p o r t i n g membe1.s c o l l e c t i v e l y by n e a n s o f t11e d e f l e c t i o n s l e n d e r n e s s r a t i o . T h i s r a t i o i s s u b s t a n t i a l l y s i m p l e r t o determine t h a n t h e magni tude o f t h e a c t u a l d e f l e c t i o n and y i e l c s a s u f f i c i e n t l y c e r t a i n r e l a t i o n s h i p f o r t h e d e t e r m i n a t i o n o f a l i m i t i n g v a l u e of' d e f l e c t i o n .

A l im i1 , ing .Jalue b a s e d on t h i s a s sumpt ion i s d e r i v e d i n F i g . 1 6 . There , a s i n F i g . 1 4 , a l l damage p o j n t s a r e p l o t t e d a s a f u n c t i o n of t l l e d e f l e c t i o n s l e n d e r n e s s and t h e e q u i v a l e n t span l e n g t h . I n t h i s c a s e , however, t h e symbols c h a r a c t e r l z e t h e most i m p o r t a n t c a u s e which was ma in ly r w e s p o n c i b l e f o r t h e l a r g e d e f l e c t i o n o f tyhe p a r t i c i p a t i n g r e i n f o r c e d c o n c r e t e member. I n o r d e r t o d e t e r m i n e t h e l i m i t i n g v a l u e s , on ly b u i l d i n g components which were p r o p e r l y c a l c u l a t e d , d e s i g n e d and manuf 'actured weye i n c l u d e d . These a r e r e p r e s e n t e d i n F i g . 16 by t h e b l a c k p o i n t s . A l l o t h e r p o i n t s i n v o l v e d rea l e r r o r s . It i s assumed t i ~ a t t i le d e s i r e d damage t i ~ r e s i l o l d i s d e t e r m i n e d o n l y by t h e b l a c k p o i n t s , and t h a t below t h i s l i m i t no damage s h o u l d have a r i s e n unde r p r o p e r c o n s t r u c t i o n . The damage-free s t a t e d e c r e a s e s more s t e e p l y w i t 1 1 i n c r e a s i n g span l e n g t h t h a n i s i n d i c a t e d i n F i g u r e 1 4 . The c u r v e i s g i v e n a p p r o x i m a t e l y by

T h i s e a s i l y remembered fo rmula i s w e l l s u i t e d t o p r a c t i c a l a p p l i c a t i o n .

Means of P r e v e n t i n g P a r t i t i o n Wall Cracks i n t h e F u t u r e ------------------ -----.------------ ------------------- One p o s s i b i l i t y , which h a s a l - r e a d y been ment ioned , I s

t o d e c r e a s e t h e bend ing s l e n d e r n e s s o f t h e r e i n f o r c e d c o n c r e t e l oad - c a r r y i n g member s u f f i c i e n t l y s o t h a t t h e above t h r e s h o l d o f damage i s n o t exceeded . I n many c a s e s , however , t h i s would l e a d t o a n uneconomica l i n c r e a s e I n p l e t e t i ~ i c k f i e s s . F o r example , a c c o r d i n g t o t h a t f o r m u l a , a r e i n f o r c e d c o n c r e t e s l a b s p a n n i n g 10 m would have t o

have a thickness of approximately 65 cm. This is approximately twice the normal thickness for plates. Consequently, hollow slabs or T-beams and

ribbed slabs have to be used.

A second possibility consists in constructing partition walls as self-supporting elements. Here, the use of reinforced brick- work is indicated (see the literature survey, Ref. 5). Self-supporting brick-filled steel frames have been tried, as well as partition walls

suspended by tension rods from an upper wall support. In the latter

case, the tension rods can be arranged so as to provide for openings. However, with all self-supporting construction the joints between the wall and the slab must be hidden by suitably designed baseboards.

A third possibility is to construct the wall so that it can follow the slab deformations without damage. In this connection it has been proposed that joints be initially cut into the wall and then finished architecturally with the aid of suitable plastic mouldings or joint covers. Results from actual applications, however, are not yet available.

It would also seem feasible to introduce an elastic support for the partition wall so that with increasing deflection there would still remain sufficient connecting force with the wall. Again, no experience is available for this type of construction.

As a final possibility, we may list measures which result in a decrease of the time-dependent deflection of the reinforced concrete load-carrying member. It would already be of great benefit if the cracks would just not get any wider, so that they could be completely closed after one, or at most two, renderings. That such possibilities exist is proven already by the fact that many of the points in Fig. 16 lie well above the proposed threshold. Above all, it is necessary to use concrete with as stiff a consistency as possible. Furthermore, the building components should have aged before the partition walls are erected. Also, prolonged moisture curing decreases the creep and shrinkage deformations of the concrete. It is therefore recommended that partition wall plastering should be left as late as possible. The most important factor, however, is to manufacture the partition walls with good mortar and and to include some reinforcement, in a few horizontal joints at least, particularly where the wall is weakened by openings.

Example: Ribbed slab in an apartment building with the following constants: tx = 10.0 m; k = 1.00; d/do = 8/35 cm; 8, = 300

kp/cm2. Rib steel St IIIb; should support non-load-carrying partition walls which are erected two months after removal of form work and are plastered one month after that. The ribbed slab will be manufactured with 300 kg/m3 cement content. It remains in the forms for 14 days, and after six months it receives a permanent live load portion of 50 kp/m2.

First Question: What is the increase in deflection from the time of plastering the partition wall until two years after the manufacture of the reinforced concrete members?

The calculation shows:

Elastic deflection due to permanently acting live load qd,in State 11: 0.29 cm

Elastlc deflection due to progressive transfer from State I to State 11: 0.00 cm

Creep due to dead load of the slab: 0.52 cm

Creep due t o dead l o a d o f t h e p a r t i t i o n w a l l : G.42 cm Creep d e f l e c t i o n due t o p l a s t e r on p a r t i t i o n w a l l : 0 . 3 0 cnl Creep d e f l e c t i o n due t o permanent2.y a c t i n g l i v e l o a d : 0 . 3 0 cm I n c r e a s e i r ~ t h e c r e e p d e f l e c t i o n due t o p r o g r e s s i v e t r a n s f e r

from S t a t e I t o S t a t e 11: 0 . 0 0 cm I n c r e a s e i n s h r i n k a g e d e f l e c t i o n : 0 .4; c m I n c r e a s e i n s h r l n k a y e d e f l e c t i o n due t o p r o g r e s s i v e t r a n s f e r

f rom S t a t e I t o S t a t e 11: EAuL!!! f = i 0 .24 cm

I n t h i s form t h e s l a b would j n a l l . p r o b a b i l i t y cause! c r a c k s i r ~ t h e p a r t l t i o n w a l l .

Second Q u e s t i o n : What i s t h e i n c r e a s e i n d e f l e c t i o n when t h e v a r i o u s m a n u f a c t u r i n g c o n d i t i o r ~ s of t h e r e i n f o r c e d c o n c r e t e member a r e changed

( a ) t h e bend ing s l e n d e l . n c s s R j h Is reduced from 32 t o 2 5 = i

1 . 3 5 cm

( b ) t h e c o n s i s t e n c y o f t h e c o n c r e t e niix i s changed s o t h a t t h e cement c o n t e n t i s r e d u c e d frorrr 300 kg/m3 t o 280 kG/m3 and t h e water /cement r a t i o d e c r e a s e d f rom 0.56 t o 0 . 5 1 - - 1 . 9 1 cm

( c ) t h e r i b b e d s l a b i s s t r i p p e d a f t e r 28 days i n s t e a d o f 1 4 days and t h e p a r t i t i o n w a l l i s e r e c t e d and f i n i s h e d one morith l a . t e r - - 1 . 8 2 cm

( d ) t h e d e s l g n s p e c i f i e s compress1 on r e i n f o r c e n l e n t Fe' = 1 d a t 24 mm O . C . e a c h way - - 1 . 8 0 cnl

T h i r d Q u e s t i o n : How s u c c e s s f u l would t h e s e measures be i n p r e v e n t i n g p a r t i t . i o n w a l l c r a c k s i f c a r r i e d o u t s in ru l t~ i . neous ly?

The p e r ~ n i s s l b l e d e f l e c t i o n would. be fSch/P.51/1000 - a c c o r d i n g t o t h e p r e v l o u s l y g i v e n r e l a t j - o n s h i p .

r i b b e d s l s b w i t h t h e p r e - ~ i o u s l y e r ~ u m e r a t e d dimensions arid m a n u f a c t u r i n g c o n d i t i o n s ( Q u e s t i o n 1 ) : f / a = 11446

i f t h e d e f l e c t i o n s l e n d e r n e s s o f t h i s s l a b h a s been r educed a c c o r d i n g t o 2 a ) : f / k = 1/740

i f a d d i i . i o n a l l y a s t i f f e r c o n s j s t e n c y o f t h e c o n c r e t e i s a s s u r e d a c c o r d i n g t o 2 b ) : f / a = 1/935

i f i n a d d i t i o n , a c c o r d i n g t o 2 c ) form work i s s t r i p p e d l a t e r and t h e partition w a l l i s e r e c t e d l a t e r : f / k = 1/1062

i f a d d i t i o n a l cornpression r e i r ~ f orcement i s i n t r o d u c e d a c c o r d i n g t o 2d): f / a = 111220

It i s c l e a r t h a t t h e g r e a t e s t b e n e f i t i s o b t a i n e d by chang ing t h e d e f l e c t i o n s l e n d e r n e s s . I n t h i s example ,compress ion re inforcemenl ; , t h e c o n s i s t e n c y , and t h e p a l - t i t i o n w a l l e r e c t i o n t h e n f o l l o w . ?'he example a l s o shows c l e a r l y how t h e wide sca t te :? al-ises i t 1 F i g s . 1 4 t o 1 6 . I t a l s o i l l u s t r a t e s t h e f a c t t h a t a number of factors which a p p e a r n e i t h e r i n t h e s t a t i c a l c a l c u l a t i o n s n o r i n t h e b u i l d i n g p l a n s a r e o f g r e a t

in ipor tance i n c o n n e c t i o n w i t i ~ p a r t i t i o n w a l l damage.

lo- EVALUATION OF EXCESSIVE SLAB DEFLECTIONS

Every owner e x p e c t s , upon occupy ing a new b u i l d i n g , t . h a t Ile s h o u l d f i n d h o r i z o n t a l f l o o r s and l e v e l room c e i l i n g s . The magni tude of d e f o r m a t i o n s which a r e found d i s p l e a s i n g and o b j e c t i o n a b l e t.o p a r t i c u l a r o b s e r v e r s va rTes w i t h i n wide l i m l t s . F r e q u e n t i y , a layman a s s o c i a t e s e x c e s s i v e d e f l e c t i o ~ i s w i t h t h e f e e l i r ~ g of d a n g e r , s i n c e he i s n o t a c q u a i n t e d w i t h t h e c a u s e s o f s l a b d e f o r m a t i o n s . Should t h i s d e f l e c t i o n i n c r e a s e s t i l l f u r t h e r wit;h t i ~ n e , owing t o c r e e p and s h r i n k a g e o f t h e c o n c r e t e o r p r o g r e s s i v e t r a r i s f o r m a t l o n t o S t a t e 11, t h i s f e e l i n g i s t r a n s f o r m e d i n t o a f e a r t h a t t h e s l a b might c o l l a p s e .

I n a c c o r d a n c e w i t h S e c t i o n 5 , t h i s c a t e g o r y o f damage a l s o i n c l u d e s c o m p l a i n t s o f tarnmed c l o s e t d o o r s o r wobbl ing t a b l e s . A l l o t h e r corisequences o f e x c e s s i v e s l a b d e f o r m a t i o n s a r e c o n s i d e r e d s e p a r a t e l y .

1 0 . 1 Magnitude o f P e r m i s s i b i e S l a b D e f l e c t i o n ---,-----------.-------------------------

I n most o f t h e c a s e s o f damage c o n s i d e r e d h e r e i n t h e o b j e c t i o n a b l e c e i l i n g deflection c o u l d be measured on l o c a t i o n . These v a l u e s were p l o t t e d i n F i g . 17 a s a f ' unc t ion o f t h e e q u i v a l e n t span l e n g t h R i . F o r f;he s a k e o f c o m p l e t e n e s s , e v e r y c a s e o f damage was e n t e r e d w i t h a s y ~ s b o l i n d i c a t i n g i t s predominant c a u s e , a l t h o u g h i n t h e p r e s e n t s t u d y t h i s d i f f e r e n t i a t i o n d o e s n o t y i e l d any p a r t i c u l a r l y u s e f u l i n f o r m a t i o n . From t h e s t a n d p o i n t of e x c e s s i v e s l a b d e f l e c t i o n a l l d.amage p o i n t s can be c o n s i d e ~ ~ e d c o m p l e t e l y e q u a l .

It i s f'ound t h a t s l a b d e f l e c t i o n i n s n ~ a l l s p a n s l e d t o complaints e a r l i e r t h a n i n l a r g e s p a n s . Obv ious ly , t h e o b s e r v e r was d i s t u r b e d l e s s by t h e a b s o l u t e magnitude o f d e f l e c t i o n t h a n by i t s magnl tude r e l a t i v e t o t h e span l e n g t h , f / R . T h i s i s a l s o e v i d e n t f rom F i g . 1 8 , . w h e r e t h e v a l u e f / R i n s t e a d o f t h e a b s o l u t e d e f l e c t i o n i s p l o t t e d on t h e o r d i n a t e .

I n b o t h p r e s e n t a t i o n s t h e s c a t t e r . o f damage p o i n t s i s ve ry l a r g e . T h i s mEy be e x p l ~ i n e d by t h e f a c t t h a t t h e p l o t t e d q u a n t i t i e s do n o t i n a l l c a s e s r e p r e s e n t t h e mi.nimum d i s t u r b i n g s l a b d e f l e c t i o n . F i r s t l y , t h e d e f ' l e c t i o n was n o t measured immedia- tely a t t h e time o f t h e i n i t i a l c o m p i a i n t . Then, a s h a s a l r e a d y been men t ioned , t h e sensitivity t o damage of' different owners i s q u i t e d i f f e r e n t and can be o p t i c a l l y f a l s i f i e d by b u i l t - i n components .

F o r t h e e s t a b l i s h m e n t o f a p e r m i s s i b l e d e y l e c t i o n , the2.e- f o r e , t h e s t a r t i n g p o i n t must be a l o w e r l i n - ~ i t i n g v a l u e t h a t w i l l p r o b a b l y meet: a l l r e q u i r e m e n t s . T h i s was e n t e r 2 e d i n b o t h f i g u r e s a s f / ~ ( - ~ 3 0 0 .

I t i s e n c o u r a g i n g t o f i n d t h a t t h i s v a l u e h a s o f t e n p r e v i o u s l y been g l v e n . The d e r i v e d v a l u e , t h e r e f o r e , p o s s e s s e s a g r e a t e r b a s i s o f c o n f i d e n c e t l ~ a n would r e s u l t o n l y f rom t h e p i o t t e d damage p o i n t s . I n t h e s t r e s s a n a l y s i s f o r r e i n f o r c e d c o n c r e t e components i t s h o u l d be n o t e d t h a t t h e s e d e f l e c t i o n s must a l s o i n c l u d e t h e e f f e c t s o f c r e e p and s h r i n k a g e , u n l i k e t h e c a s e o f wood arid s t e e l - g i r d e r s l a b s . The e l - a s t i c d e f l e c t i o n o f r e i n f o r c e d c o n c r e t e b u i l d i n g components must t h e r e f o r e be o n l y a f r z c t i o n o f t h e c i t e d l i m i t .

10.2 Measures by \ihicll E x c e s s i v e D e f l e c t i o n Can Be P r e v e n t e d ---..---------------------------------- ---- - ----.--- F r e q u e n t l y , t h e d e f l e c t i o n i s d e t e r m i n e d n o t o n l y by t h e

d e f o r a a t i o n o f tihe s l a b b u t a l s o by t h e d e f o r m a b i l i t y o f t h e s u p p o r t g i r d e r o r t h e f l e x i b i l i t y o f t h e s u p p o r t r e s t r a i n t s . F o r t h e two-way r e i n f o r c e d mul t ip l e -bay s l a b of Case No. 106 , f o r example, t h e r e p o r t e d d e f l e c t i o r r was a p p r o x i m a t e l y 1 C err,. The s l a b i t s e l f d e f l e c t e d a b o u t 6 cm and t h e s u p p o r t s , on t i le a v e r a g e , a b c u t 4 cm. F o r t h e s e r v i c e - s t a t i o n 1-0of o f Case No. 128 , t h e d e f l e c t i o n o f 34 cm et t h e f r e e end o f t h e c a n t i l e v e r compr ised defo-mat ions o f t h e c a n t i l e v e r p l a t e , t h e b e n d i n g o f t h e f l e x i b l e r e i n f o r c e d c o n c r e t e columns, t h e f l e x u r 2 l l o a d i n g o f t h e U-shaped f o u n d a t i o n beams and t h e f l e x i L i l i t y o f t h e f o u n d a t i o n s o i l . Such e f f e c t s must obviously be c o n s i d e r e d d u r i n g t h e p l a n n i n g s t a g e .

E x c e s s i v e s l a b d e f l e c t i o n can a lways be c o u n t e r e d by all a p p ~ o p r i a t e l y chosen camber i n t h e form work. I n normal s i t u a . t i o n s , a camber of L/300 i s s ~ i f f ' i c i e n t . F o r l t i rge span l e n g t h s o r some s p e c i a l c a s e s descr : ibed , t h e r e q u i r e d an:oun': must be c a l c u l . a t e d .

O f ' c o u r s e , t h e dange r o f e x c e s s i v e s l a b i l e f l e c t i o n call be d l m i n l s h e d by r e d u c l n g c r e e p and s h r i n k a g e d e f o r m a t l o n of t h e c o n c r e t e ( s e c S e c t i o n 3 . 3 ) .

The f o l l o w i n g f i g u r e s a r e i n t e n d e d t o show t h a t i n s 1 , r u c t u r e s which con ta i r ! a form-work camber o f L/300, e x c e s s i v e s l a b d e f l e c t l o r 1 mzy be avo ided s-imply by o b s e r v i n g t h e pernl iss ib1.e d e f l e c t i o n s l e n d e r n e s s of max. L / h : 35. Acco-ding t o F i g . 1 9 , unde r f u l l u t i l i z - a t i o n of t h e permissible c o n c r e t e and s t e e l s t r e s s e s and unde r a v e r a g e c r e e p and s h r i n k a g e d e f o r r i a t i o n s o r a c o n c r e t e B 225, a dange rous s l a b deflect : -on i s t o bti e x p e c t e d only a t s l e n d e r n e s s r a t i o s g r e a k e r t h a n 26. When i t I s a l s o c o n s i d e r e d t h a t t h e pe rmanen t ly a c t i n g l o a d i s o r d i n a r i l y o n l y abou t 75 p e r c e n t o f 1.he c a l c u l a t e d maxlmum l.oad, t h e n a c c o r d i n g t o F i g . 50 a e f l e c t i o r ~ s l e r ~ d e r i l e s s e s up t,o 35 riiay be used w i t h o u t damage. I f ' , unde r e x c e p t i o n a l c i r c u m s t a n c e s , f o r i n s t a n c e unde r 1;oo e a r l y removal o f forr-I wor!:, l a ~ g e r c r e e p and s h r i n k a g e d e f o r m a t i o n s of t h e c o n c r e t e t h a n I$ = 3 and E~ = 0.30% o c c u r , t h e n acco:-ding t o F i g . 21 t h e d a n g e r o f e x c e s s i v e d e f l e c t i o n i n c r e a s e s .

11. EVALUATION OF OBSERVED CRACKS I N REINFORCED CONCRETE BUILDING

COMPONENTS

A s h a s a l r e a d y been i n d i c a t e d : t h e t y p e s of' damage enccjmpassed i n t h i s group dfi n o t c o n s t i t u t e t r u e d e f l e c t i o n damage. They were , h o w e - ~ e r , repo.;.ted a s such i n tihe c c n t e x t o f t h e conduc ted s u r v e y , s i n c e e x c e s s i v e d e f l e c t L o n o f r e i n f o r c e d c o n c r e t e b u i l d i n g ccmponents h z s o c c u r r e d a s a 1-esu l t o f t h e e y r o r s committed i n t h e manufac tu re G r

d e s i g n .

F r e q u e n t l y , v e r y wiae c r a c k s o c c u r r e d i n t h e t o p s u r f a c e o f a r e i n f o r c e d c o n c r e t e s l a b o v e r a p a r t i t i o n w a l l t h a t was o r i e n t e d i n t h e same d i r e r ; t i o r ~ a s t l ~ e s1z.b s p a n ( F t g . 2 4 , ~ o s i t i o n 1 ) . The s l a b had d e f l e c t e d and c o n s e q u e n t l y came t o res t on t h e p a r t i t i o n w a l l . Thus bend ing moments r e s u l t e d normal t o t h e main reinforcement d i r e c t i o n which l e d 'GO c r n c k s a f t e r t h e bend jng t e n s i l e s t r e n g t h o f t h e c c n c r e t e had been exceeded . T h i s damage c o u l d have been a v c i d e d e n t i r e l y by means o f an e l a s t , i c l a y e r between t h e wa1.l and t h e s l a b . The i n c l ~ r s i o n o f t o p rBeinfo:.cemcnt i n t h e d e s i g n would have r educed t h e w i d t h of t h e c r a c k s .

S i m i l a r c r a c k s i n t h e t o p s u r f a c e o f r e i n f o r c e d c o n c r e t e s l a b s o c c u r r e d where t h e t o p r e i r , f o r c e n l e n t was p l a c e d t o o low o r was o f j n s u f f i c l e n t amount. The c r a c k s u s u a l l y o c c u r r e d a t t h e edge o f t h e s u p p o r t i n g j ~ i s t o r a t t h e end o f t,he s o l i d edge s t r i p ( F i g . 2 3 ) . Whereas t h e c r a c k s d e s c r i b e d u n d e r ( a ) were t h e r e : ; u l t o f i n c o n ~ p n t i b : l i t y o f d e f o r m a t i o n s , t h e c r a c k s which r u n normal t o t h e s p a n u s u a l l y indicate s e r i o u s d a n g e r w i t h r e g a r d t o t h o l o a d c a r r y i n g c a p a c l t y o f t h e p l a t e . U s u a l l y , t h e p e r r n i s s l b l e s t e e l stress i s g r e a t l y exceeded w i t h i n t h e c r a c k s e c t i o n ; a l s o t h e c o n c r e t e s t r e s s e s a r e Loo h l g h . Fur>thermore , i n t h i s manner t h e p e r m i s s i b l e s t r e s s e s a t t h e p l a t e c e n t r e may be exceeded owing t o a r e d i s t r i b u t i o n o f i n t e r n a l f o r c e s t h r o u g h r e l a x a t i o n o f t ,he r e s t r a i n t s .

I n s l a b s s u p y ~ o r t e d on a l l f o u r s j d e s wide c r a c k s have f r e q u e n t l y been o b s e r v e d i n t h e c o r n e r s , o r i e n t e d normzl t o t h e d j a g o n a l s . Accord ing t o p l a t e t h e o r y i t i s kcown t h a t a t th!-s l o c a t i o n s u b s t a n t i a l t w i s t i n g moments can e x i s t , d e p e n d i n g on t h e s u p p o r t c o n d i t i o n s . F r e q u e n t l y t h e r e was no s u i t a b l e r e i r f o r c e m e n t which c o u l d r e s i s t thc: f o r c e s a c r o s s t h e c o r n e r s , b e c a u s e a one-way s l a b had been assumed f o r s i m p l i f i c a t i c j n o f t h e c a l c u _ l a t i o n s . I n d e t a i l i n g , no t e n s i l e r e i n f o r c e - ment had been s p e c i f i e d . A s a n example , F i g . 24 shows t h e p1a.n view o f a n a p a r t m e n t house w i t h such d i a g o n a l c r a c k s .

I n two-way re inforaced c e i l i n g s l a b s s u c h c r a c k s a l s o o c c u r r e d whenever t h e r e i n f o r c e m e n t bras i r ~ s u f f i c i e n t o r t h e : i t e e l was d e p r e s s e d d u r i n g pl acenient o f c o n c r e t e . Both e12 ro r s n o t o n l y i nc rc t a se t h e d e f l e c t i o n o f t h e s l a b b u t a l s o i n f l u e n c e t h e c a r r y i n g c a p a c i t y .

A t h i r d r e a s o n f o r t h e o c c u r r e n c e o f e x c e s s i v e l y wide d i a g o n a l c r a c k s i s t o be found i n t h e d e s l g n d i r e c t i v e s o f t11e reinforced c o n c r e t e code D I I i 1045 app1ic:able a t t h a t t i - m e . The t o r s i o n r e l n f o r c e m e n t i n t h e f r e e c o r n e r s was r e q u i r e d t o e x t e n d o n l y o v e r a l e n g t h o f m2.x. L i 5 . Tlie t o r s i o n a l moments, however , e x t e n d eve:- a g r e a t e r r e g j o n . T h i s J . s pal-titularly n o t i c e a b l e i n l a r g e s p a n s a n d , a.s shown i n t h e example i n F i g . 24 on t h e l e f t s i d e , i s f u r t h e r a c c e n t u a t e d by t h e d i f f e r e n t i 2 . l s t f f f n e s s o f edge s u p p o r - t s . Consequen t ly , d i a g o n a l c r a c k s o c c u r r e d even a t t h e edge o f t h e t o r s i o n r e i n f o r c e m e n t which was p l a c e d i n a c c o r d a n c e w i t 1 1 D I N 1045 . S i n c e t h e r e w s s a n a l m o s t comple t e a b s e n c e o f s t e e l i n t h a t r e g i o n , t h e craclcs a r e u n a c c e p t a b l y w ide .

The l a t t e r d e f e c t i s t o be removed i n t h e r e - ~ i s i o n s o f t h e lde inforced c o n c r e t e code . It i s i r ~ t e n d e d t h a t d i a g o n a l r e i n f o r c e m e n t w i l l be p r o v i d e d f o r a wic!th o r 0 . 2 R, and a l e n g t h o f 0 . 4 R x a t t h e t o p s u r f a c e o f t h e s l a b . On t h e l ower s u r f a c e t h e sarne r e ln fo rcemen t ; i s r e q u i r e d i n t h e normal C i r e c t i o n . The r e g i o n c o v e r e d w i t h t h i s p r o p o s a l i s ; n d i c a t e d by a dashed l i n e i n a c o r n e p o f F i g . 25.

EVALUATION OF HORIZONTAL CRACKS I N THE VICINITY OF SLAB SUPPORTS

These c r a c k s a p p e a r e d e i t h e r below o r above t h e s l a b s u p p o r t . I n t h i s connect:-on i t was f r e q u e n t l y o b s e r v e d t h a t one o r two l a y e r s o f b r i c k were encompassed by t h e s u p p o r t movement. U s u a l l y t h e c r a c k s o c c u r r e d i n t h e - ~ i c i r ~ i t y o f t h e r o o f s l a b i m m e d i a t e l y below t h e e a v e s . T h r e e d i f f e r e n t c a u s e s a r e r e s p o n s i b l e f o r t h e f o r m a t i o n o f t h e s e c r a c k s .

I n a d d i t i o n t o tlie s t r m u c t u r a l i .nf l u e n c e s whlch a f f e c t t h e 1 - o t a t i o n o f t h e edge s u p p o r t , a hor . izori ta1 nloverr~ent o f t h e r e i n f o r - ced c o n c r e t e components o c c u r r e d owing t o s h r l n k a g e o f t h e c o n c r e t e o- changes i n t e m p e r a t u r e . The e x t e r i o r p l a s t e r f i n i s h c o u l d n o t f o l l o w t h i s defo:-mation and cr t icked . A t y p i c a l example i s shown i n F i g . 26 . The r.equj.red t h e r ~ i i a l i n s u l a t i o n was m i s s i n g f rom t h e rae inforced c o n c r e t e n l a b . The c e i l i n g t h e r e f o r e expe r2 ienced l a r g e t e m p e r a t u r e changes . I f t h e t h e r n a l measures a l o n e a r e n c t s u f f i c i e n t t o t a k e c a r e o f e l o n g a t i o n s , d a m a g e can be a v c i d e d by p l a c i n g a 12 cm d e t a c h e d c o v e r w a l l i n f r o n t o f t h e s l a b c o n c r e t e .

A s i m i l a r exarr:ple i s shown i n F i g . 2 7 . F o r 16.rge expan- s i o n s i t wou1.d a l ~ o b e p o s s l b l e t o c h a n n e l t h e u n a v o i d a b l e c r a c k s i r l t h e b r i ckwork and p l a s t e r i n t o a p r e d e t e r m i n e d l o c a t l o n by i n c l u d i n g a p l a n n e d j o i n t i n t h e br ic l iwork and p l a s t e r . The c r a c k c o u l d t h u s b e made i n v i s j b l e .

Where t h e e x p a n s i o n w a s n o t t o o g r e a t and a. s u f f i c i e n t i r ~ s u l e t i o n o f t h e r e i n f o ~ c e d c o n c r e t e p l a t e h a s been p r o v i d e d , t h e r e a s o n f o r t h e h o r i z o n t a l c r a c k s may be found i n t h e r o t a t i o n o f t h e edge s u p p o r t . I t s magni tude

grows l i n e a r l y w i t h t h e l o a d and t.he b e n d i n g s l e n d e r n e s s o f t h e b u i l d i n g component. The da.nger o f c r a c k f o r m a t i o n due t o a si . lpport r o ' c a t i o n i s ther fe for t? a lways prBesei?t a t h i g h s t r e s s l e v e l s and i n s l e n d e r a f l e x u r a l members, n o t o n l y !.n l a r g e - s p a n f l e x u r a l members.

The edge r o t a t ' o n i s p a r t i c u l a r l y dange rous when deep g i r d e r s a r e u s e d a t t h e s u p p o r t s , a s shown i n F i g s . 28 t o 3 0 . I n t h e f i r s t c a s e t h e l igh t -v :e ight c o n c r e t e pa l !e l s Iiave a p p a r e n t l y pushed f a r beyond t h e o u t e n edge o f t h e e x t e r i o r w a l l . I n t h e o t h e r two c a s e s some p o s s i b l e c r a c k f o r m a t l o n s n r e i n d i c a t e d s c h e m a t i c a l l y .

I n s o f a r a s tlie few r e p o r t s of s u c h h o ; ? i z o n t a l c r a c k s p e r m i t a c o n c l u s i o n , i t may be assumed t h a t u n d e r p r o p e r e x e c u t i o n and ob:;ervance fif t h e p e r i n i s s l b l e s l e n d e r n e s s r a t i o s t h e c r a c k s shown i n F i g s . 29 and 30 may be a v o i d e d . The h o r i z o n t a l c r a c k s which a r e p o s s i b l e in t h e v i c i n i t y o f the e a v e s may i n v a r i a b l y be e l i m T n a t e d by a s u i t a b l y desig1;ed suppo:-t .

T h e o r e t i c a l l y , h o r i z o n t a l c:-acks a r e a l s o p o s s i b l e betweer1 t h e w a l l a n d t h e s1a.b at t h e i r i t e r m e d i a t e s u p p o r t s o f a c o n t i n ~ l o u s s l a b ( F i g . 3 1 ) . However, t h e r e must b e g r e a t d i f f e r e n c e s i n span length ; ; o r l o a d i n g c o n d i t i o n s . No r e p o r t s o f s u c h damage a r e ava i1abJ . e . T h i s t1ieort.t i c n l p o s s i b i l i t y h a s been t a k e n f rom t h e l i t e r a t u r e .

I n two-way r e i n f o r c e d s l a b s h o r i z o n t a l c r a c k s f r e q u e n t l y d e v e l o p e d i n t h e b r i ckwork n e a r t h e c o r n e r s , s l n c e t h e r e t h e s l a b i s a b l e t o l i f t o f f t h e brj-ckwork ( F i g s . 32 and 3 3 ) . Robenhagen ( R e f . 6 )

p o i n t s o u t t h a t i n a d d i t i o n t o t h e h o r i z o n t a l c r a c k s i n t h e b r i c k w o r k , c r a c k s i n c l i n e d a t a p p r o x i m a t e l y 45' may a l s o a p p e a r . Such c r a c k s were r ~ o t o b s e r v e d i n t h e c o n t e x t o f t h e p r e s e n t s u r v e y .

A l l h o r i z o n t a l c r a c k s i n t h e v i c i n i t y o f s l a b s u p p o r t s d e s c r i b e d h e r e i n can be t r a c e d ma in ly t o d e s i g n d e f i c i e n c i e s and c o u l d e a s i l y have been a v o i d e d . I n a d d i t i o n t o t h e p r e s e n t a t i o n o f examples , t h e r e f o r e , i t seemed s u f f i c i e n t t o p o i n t o u t t h e c a u s e s o f t h e damage t h a t had o c c u r r e d and s imp ly t o i n d i c a t e s u g g e s t i o n s f o r improvements .

1 3 . EVALUATION OF DAMAGE TO PLASTER AND FINISHES

Damage t o p l a s t e r and f i n i s h e s was c o n s i d e r e d o n l y i f it was a d l r e c t consequence of e x c e s s i v e d e f l e c t i o n of r e i n f o r c e d c o n c r e t e s l a b s . Damage due t o t h e i n c o r r e c t a p p l i c a t i o n o f p l a s t e r o r tihe f i n i s h i n g s u r f a c e i s n o t i n v e s t i g a t e d h e r e . F ' u r t h e r i n f o r m a t i o n r e g a r d - i n g t h i s a r e a can be o b t a i n e d from t h e l i t e r a t u r e ( R e f . 7 ) .

Also e x c l u d e d a r e p l a s t e r c r a c k s which have o c c u r r e d as a n e c e s s a r y consequence o f o t h e r d e f l e c t i o n damage, e . g . t h e c?acks i n t h e w a l l p l a s t e r o f a c r a c k e d p a r t i t i o n w a l l o r t h e h o r i z o n t a l c r a c k s i n t h e e x t e r i o r s t u c c o due t o s u p p o r t r o t a t i o n .

A s w i l l be shown s u b s e q u e n t l y , a l l p l a s t e r and f i n i s h i n g damage t h u s d e f i n e d can be a s c r i b e d t o d e s i g n o r c o n s t r ~ ~ c t i o n e r r o r s . A t l e a s t t h e y have a r i s e n as a consequence o f such e r r o r s . T h e r e f o r e , a s i n t h e p r e v i o u s s e c t i o n , on ly c h a r a c t e r i s t i c c a s e s o f damage w i l l be enumera ted and s u g g e s t i o n s f o r impraovements w i l l mere ly be i n d l - c a t e d .

I n a c e r t a i n b u i l d i n g t h e e x p a n s i o n j o i n t be tween t h e wall and t h e r e i n f o r c e d c o n c r e t e c e i l i n g was cove red w i t h p l a s t e r ( F i g . 3 4 ) . During t h e s l a b d e f o r m a t i o n , t h e p l a s t e r b u c k l e d and s p a l l e d from t h e \ g a l l .

A r e i n f o r c e d c o n c r e t e r i b b e d s l a b w i t h t h r e e c r o s s r i b s was j o i n e d t o an erld w a l l para! l e l t o t h e s p a n . T h e r e , i t s u p p o r t e d i t s e l f o v e r t h e c r o s s r i b s l i k e a s l a b support ,ed on f o u r s i d e s . The c r o s s r i b s became g r e a t l y o v e r l o a d e d and deve loped a l a r g e s h e a r c r a c k w i t h i n t h e las t r i b s p a c i n g ( F i g . 35) . The l a r g e d e f o r m a t i o n o v e r a s h o r t d i s t a n c e l e d t o s p a l l i n g and c r a c k i n g o f t h e c e i l i n g p l a s t e r .

I n o r d e r t o a v o i u t h i s u r ~ i n t e n t i o n a l s u p p o r t c o n d i t i o n o f t h e c e i l i n g , a compress l .b le l a y e r was p l a c e d below t h e c e l . l i n g c l o s u r e , and t h e r i b s i n t h e v i c i r l i t y o f t h e f a c a d e were s t r e n g t h e n e d . Even a l a y e r o f s a n d u n d e r t h e c e i l i r i g s u p p o r t which i s removed s h o r t l y b e f o r e t h e s t r i p p i n g o f t h e forms,would o b v i a t e t h e d a n g e r o f ove r - s t r e s s i n g t h e c r o s s r i b s .

I n e n o t k e r b u i l d i n g a v a l u a b l e p l a s t e r c e i l i n g had t o be r e p a i r e d many t i m e s s i n c e u n s i g h t l y c r a c k s a p p e a r e d r e p e a t e d l y . It was a s c e r t a i n e d t h a t t h e s e c r a c k s were n o t due t o i m p r o p e r m a n u f a c t u r e o f t h e c e i l i n g p l a s t e r . Even r e l a t i v e l y small d e f o r m a t i o n s o f t h e r e i n - f o r c e d c o n c r e t e s l a b c a u s e d c r a c k i n g o f t h e p a r t i c u l a r l y s e n s i t i v e s t u c c o gypsum. Dur ing t h e i n v e s t i g a t i o n i t was e s t a b l i s h e d t h a t t h e t o p

r e i n f o r c e m e n t l a y e r was d e p r e s s e d a n d t h e r e q u i r e d t h e r m a l insulation a[;ain::t t h e open a t t i c was a b s e n t .

F i g u r e 36 shows t h e i n f l u e n c e o f t i l e t h e r m a l i ~ s u l a t i o n on t h e t e m p e r a t u r e f l u c t u a t . i o n s of' a r a e i n f o r c e d c o n c r e t e p l a t e as ca l cu l a t , e r l a c c o r r l i n g t o D I N 4108 . by means o f a s u i 1 . a b l e e x t e r i o r c e l l inp, J n s u l a t i o n t h e s e a s o n a l t e m p e r a t u r e var3 a t i c ~ n s c a n b e lseduced f rom 33O t o l l ° C . Such rnear,ursec a l s o d i m i n i s h t h e d a n g e r o f h o r i z o n t a l c r a c k i r ~ p , I n t h e e x t e r j o r s t u c c o be l cw t h f ? c e i l lnp; s u p p o r t s , a s d e s c r l bed I n S e c t i o r ~ 1 2 .

A d i f f e r e n t ; c a u s e was f o u n d for . t h e c r a c k s ir, t h e c e i l l n g p3a : ; t f . r shown i n F j g . 37 . Theso c r a c k s a r o s e b e c a u s e t h e c e i l i n g s l a b was u n l n f . e n t l o n a 3 l y s u p p o r t e d by a p a r t i 1 , i o n w a l l .

D a m a ~ e , which a t f j r s t s i g h t a p p e a r e d danp;erous , o c c u r r e d d u r j n ~ a d e d i c a t i o n ceremony o f a s c h o o l b u i l d i n g . A f s l s e c e i l i n g s ~ r s p e r ~ d e d from o canl , l l e v e r e d b a l c o n y o f t h e a s s emb ly h a l l t o r e of ' f w i t h a lour1 bank:. P a n i c s t , r i c k e n , t h e guest:; l e f t t h e b a l c o n y . k!owever, o n l y t h e c r a c k a t t i l e f r e e c a n t i l e v e r find h a d fo rmed , a s shown :'.n F i g . 38. T h e c r a c k d e v e l o p e d a l o n g t h e f r o n t e d g e a c r o s s t h e whole w i d t h o f t h e b:ilcony .

F ~ o m t t ~ e d e s i g n p o i n t of' v iew i l . was wrong f o r t h e s u s - pended c e i l i n y , 1,o be i n t e y ; r a l I y c o r ~ n e c t e d t o t h e r . e in for .ced c o n c r e t e s l a b a t t h e c a n t i l e v e r e n d . B e f o r e t h e c r a c k fo rmed , t h e c e i l i n g a c t e d w i t 1 1 t h e 1 .e1nforced c o r ~ c r e t e p l a . t e as a c a n t i l e v e r ~ : i r d e r o f t . r i a n g u 1 a . r h e i g h t v a r i a t i o n . The s u s p e n d e d c e i l i n p : , a c t i n g a s thtt c o m n r e s s i o n zone o f t h i s g i r d e r , was s u b j e c t e d t o c o n s i d e r a b l e cornpre!ssive f o l . ces which e v e n t u a l l y l e d t o a s h e a r f a i l u r e ! a t t h e jo!nt w3.th t h e r e i n f o r c e d c o n c r . e t e p l a t e .

R e p e a t e d l y i t was r e p o r t e d t h a t v a r i o u s p o r t l o n s o f p l a s t e r , including p l a s t t ! r s u p p o r t s , f e l l o f f . I n orle b u i l d i n g w i t h c : ross -wal l c o n s t r u c t i o n , tihe wnll. p l a t , e s which were s i t u a t e d o n b o t h s i d e s o f a c o r r i d o r , had r o t a t e d i n w a r d s , b u c k l i r ~ g t h e a c o u s t i c a l t i l e s . C o n s e q u e n t l y , i n d i v i d u a l t i l e s f e l l o f f ( F i g . 3 9 ) . Whether t h f ? wal l r o t a t i o n was t h e : ;ole r e a s o n t 'or t h e f a i l w e o f t h e a c o u s t i c a . 1 t i 1 . e ~ c o u l d n o t b e d e t e r m i ~ e d w l ~ t h c e r t a i n t y f rom t h e a v a i l a . b l e i n f o r m a t i o n .

I n a c e r t a l n a p a r t m e n t b l ~ o c k w i t h p r e c a s b s l a b s t h e ca . s t - i n - p l a c e c o n c r e t e i n many s t o r e y s was m a n u f a c t u r e d s o p o o r l y t h a t t h e l o a d s had t o b e c a r r i e d s o l e l y by t h e p r e c a s t g i r d e r s . The c e i l i n g d e f l e c t i o n was t h e r e f o r e v e r y l a r g e . S i n c e some o f t h e l i g h t - w e i g h t p l a t e s which were t o c a r r y t h e p l a s t e r were u n f o r t u n a t e l y s e c u r e d w i t h n a i l s o f i n s u f f i c i e n t l e n ~ t h , t h e l a r g e c e i l i n g c u r v a t u r e l e d t o t h e s p a l l i n g o f i n d i v i d u a l p l a t e s .

1 4 . I ? V A L U A T I O N O F D E F L E C T I O N DAMAGE I N I S O L A T E D C A S E S

F i g u r e 40, whic:h h a s b e e n t a k e n f rom t h e p u b l i c a t i o n of G . F'ranz ( R e f . a ) , sttows t h e d e s t r u c t i o n o f a d i s ~ l l a y window where

i n s u f f i c i e n t a l l o w a n c e h a s been made f o r d e f l e c t i o n o f t h e o v e r l y i n g r e i n f o r c e d c o n c r e t e g i r d e r . The window had t o be r e p l a c e d s e v e r a l t i m e s because no a t t e n t ; i o n had been p a i d t o t h e f u r t h e r i r lcr1ease o f d e f l e c t i o n due t o c r e e p arid s h r i n k a g e o f t h e c o n c r e t e . F r a n z p o i r - t s o u t t h a t sirri i lar2 f a i l u r e s h a v e a l s o o c c u r r e d j n w a l l s made o f g l a s s b r i c k s .

I n a s i n g l e - s t o r e y o f f i c e b u i l d i n g t h e s t e e l columns o f a long-span r e i n f o r c e d c o n c r e t e c e i l i n g had b e n t ( F i g . 4:). The f l e x u r a l d e f o r m a t i o n due t o c r e e p and s h r i n k a g e o f t h e c o n c r e t e i n c r e a s e d t o s u c h an e x t e n t t h a t t11e co l . l apse o f t h e c e i l i n g was e x p e c t e d due t o b u c k l i n g o f t h e b e n t s t e e l columns. By means o f c o s t l y r e m e d l a l measures t h e damage was e l i m i r i a t e d . T h i s example shows t h a t a t t h e edges o f long-span c e i l i r ~ g s , t h e a c l d i t i o n a i b e n d i n g moments due t o t h e d e f o r m a t i o n o f t h e c e i 1 i r . g must be d e t e r m i n e d and t h e i r s a f e r e s i s t a n c e e s t a b l i s h e d .

With l ' l a t r o o f s , e x c e s s i v e d e f l e c t i o n s may p roduce a d e p r e s s i o n i n vihich w a t e r accumu'ates . I n t h e c a s e i l l u s t r a t e d i n F ig .42 i t was su rmised t h a t owing t o a l e a k i n g r o o f membrane t h e t h e r m a l i n s u l - a t i n g l a y e r on t h e r e j n f o r c e d c o n c r e t e s l a b and t h e r e i n f o r c e d c o n c r e t e c e i l i n g b e n e a t h became sa tux -a t ed . A s a r e s u l t , some o f t h e a c o u s t i c a l t i l e s which were g l u e d t o t h e c e i l i r - g cane l o o s e and f e l l o f f .

F i g u r e 4 3 , which was a l s o t a k e n from t h e p u b l i c a t i o n of G . F r a n z , s h o t ~ s a c a n t i l e v e r r o o f which was i n t e n d e d t o d l -a in t owards t h e i n f ; e r i o r . Due t o e x c e s s i v e d e f l e c t i o n arl o p p o s i t e g r a d i e n t r e s u l t e d . The w a t e r dra.inec1 o v e r t h e cdge o n t o a busy t h o r o u g h f a r e i n s t e a d o f t o t h e i n t e r i - o r of t h e r o o f . The d i a g o n a l g i r d e r s k e t c h e d i n t h e d r a w i r ~ g had t o be e r e c t e d .

F o r t h e expans ion j o i n t shown i n F i g . 4 4 i t rras n o t con- s i d e r e d t h a t t h e t r o u g h s u p p o r t s were more f l e x i b l e t h a n t h e r e i n f o r c e d c o n c r e t e s h e l l . A gap r e s u l t e d which was up t o 4 cm wide . The gap was n o t o n l y uns igh tLy b u t a l s o d i s r u p t e d t h e normal f u n c t i o n i r ~ g o f tihe t r o u g h . Here a l s o , c o s t l y r e m e d i a l measures were n e c e s s a r y .

I n a m u l t i - s t o r e y bu f - ld ing (FLg. 4 5 ) t h e main s t r u c t u r a l c o n f i g u r a t ; i o n c o n s i s t e d o f a f rame w i t h l a r g e p r o j e c t i n g c a n t j l e v e r f l c o r s l a b s and t h e e x t ; e r i o r w a l l o f e1.n a t t a c h e d alu.minum c u r t a i n w a l l . S i n c e f o r v a r i o u s r e a s o n s t h e d e f l e c t i o n s i n t h e s e p a r a t e s t o r e y s c o u l d no t be o f e q u a l magn i tude , t h e alumlnum c u r t a i n w a l l was s u b j e c t e d t o e x c e s s i v e a x i a l l o a d s . A s a l ' e s u l t , 11, warped t o such an e x t e n t t h a t d e s p i t e a n t i c i p a t e d t o l e r a n c e s a 1-arge number o f windows jammed.

The s t e e l s t r a p s shown i n F i g . 46 were i n s t a l l e d ir. o ~ l d e r t o s t i f f e n bathroom p a r t i t i o n w a l l s which weye e r e c t e d i n t h e base- ment and which d j d n o t r e a c h t h e c e i l i n g . The s t r a p s b e n t approxj -mate ly 3 cm due t o t h e d e f l e c t i o n o f t h e r e i n f o r c e d c o n c r e t e c e i l i n g b e c a u s e no gap had been providec! i n t h e v e r t i c a l d i r e c t i o n .

Pef ' l ec t ic ln damage Is a l s o p o s s i b l e i n p r e - s t r e s s e d c o n c r e t e s l a b s . I n one c a s e i t was 1 ;epor ted t h a t a p r e - s t r e s s e d p re - f a b r i c a t e d s l a b had g r a . d u a l l y d e f l e c t e d upwards and c o n s e q u e n t l y l i f t e d o f f t h e s u p p o r t s . The s l a b had been c a l c u l a t e d f o r a r e l a t i v e l y h i g h l i v e l o a d which f o r economic r e a s o n s , however , had n o t been a p p l i e d f o r a l o n g t i m e . Because o f c r e e p a c t i o n i n t h e c o n c r e t e , t h e d e f o r m a t i o n Lncreased a s a r a e s u l t o f t h e p1 . e - - s t r e s s ing t h a t was t o have opposed t h e l i v e l o a d . S e v e r a l c a s e s o f t h l s n a t u r e have been o b s e r v e d i n England , and w i l l be descz.ibed f u r t h e r i n t h e n e x t s e c t i o n .

1 5 . RESULTS OF QUESTIONNAIRE ON DEFLECTION DAMAGE I N OTHER COUNTRIES

15.1. R e p o r t s o f Cases o f Damage

The t y p e s o f damage o b s e r v e d i n West Germany a l s o o c c u r r e d i n o the l ' c o u n t r i e s wherever s i m i l a P l y h i g h c o n c r e t e and s t e e l s t r e s s e s and s i n ~ i l a r l y la . rge s l enc l e rnes s r a t i o s were i n u s e . I n g e n e r a l t h e same damage p o s s i b i l i t i e s were men t ioned . One a d d i t i o n a l r e a s o n was g i v e n f o r t h e l a r g e d e f l e c t i o n o f r e i n f o r c e d c o n c r e t e components b e s i d e s t h o s e a l r e a d y ment ioned i n S e c t i o n 8 . I n England , l a r g e d e f o r m a t i o n s o c c u r r e d f r e q u e n t l y i n s l a b s w i t h f l o o r h e a t i n g , e s p e c i z l l y when t h e c o n c r e t e had been manufac tu red w i t h s h r i n k a g e - s e n s i t i v e a g g r e g a t e s f ~ * o m S c o t l a n d (Hefe-ence 9 ) .

I n c o u n t r i e s i r ~ which l o w - s t r e n g t h c o n c r e t e and s t e e l a r e s t i l l i n u s e p r e d o m i n a n t l y , f o r i n s t a n c e i n Turkey , Greece , Yugoslav:a, e t c . , d e f l e c t i o n damage I s p r a c t i c a l l y unknown. It a l s o became q u i t e a p p a r e n t t h a t l e s s damage was i n c u r r e d i n c o u n t r i e s i n which s m a l l e r s l e n d e r n e s s r a t i o s were p r e s c r i b e d t h a n h e r e . I n Sweden, f o r example , t h e damage w a s g r e a t l y r e d u c e d a f t e r t h e i n t r o d u c t i o n o f t h e new code r e g u l a t i o n s s h o r t l y a f t e r World War 11. P a r t i t i o n w a l l c r a c k s were p r e v e n t e d main ly by t h e s t i p ~ l a t ~ i o n t h a t t h e s u p p o r t i n g r e i n f o r c e d c o n c r e t e f l e x u r a l members were t o remain i n S t a t e I . T h i s i s a c h i e v e d i n d i r e c t l y by a r u l e o f thumb f o r determin:Lng t h e minimum t h i c k n e s s o f b u i l d i n g components ( s e e S e c t i o n 1 5 . 1 ) . I n England , a l s o , t h e new r e i n f o r c e d c0ncret .e p r o v i s i o n s i n t r o d u c e d i n 1957 r e s u l t e d i n some r e d u c t i o n o f t h e s u s c e p t i b i l i t y c f s t r u c t u r e s t o damage.

The 1 .e inforced c o n c r e t e r e g u l a t i o n s i n t r o d u c e d i n S w i t z e r l a n d i n 1956 had t h e o p p o s i t e e f f e c t . Whereas u n t i l t h e n s u b s t a n t i e l l y s m a l l e r s l e r ~ d e r n e s s r a t i o s and lower c o n c r e t e and s t e e l s t r e s s e s were p e r m i t t e d t h a n w i t h u s , t h e new p r o v i s i o n s p e r m i t t e d t h e u s e o f any a r b i t r a r y s l e n d e r n e s s r a t i o . Not even a d e f l e c t i o n c a l c u l a t i o n i s p l - e s e n t l y r e q u i r e d i n Swi t ze r l z .nd . A s a consequence , an a s t o n i s h i n g amount o f damage h a s o c c u r r e d . The f r e q u e n c y o f damage i n c r e a s e d s t i l l fu r the : - when t h e s t e e l s t r e s s e s were b r o u g h t up t o t h e h j -gher v a l u e s p e r m i s s i t : l e i n Germany, w i t h o u t r e g a r d f o r t h e c o r r e s p o n d i n g duformat-,ion c r i t e r i a . Consequen t ly , t h e r e v i s i o n o f t h e code p r o v i s i o n s a t p r e s e n t unde r s t u d y i n S w i t z e r l a n d w i l l e g a i n i n t r o d u c e a s e c t i o n on de f l e c t i c n c o n t r o l .

1 5 . 2 S t u d i e s o f D e f l e c t i o n Damage i n O t h e r C o u n t r i e s

I n a d d i l . i o n t o t h e i n v e s t i g a t i o n a l r e a d y men t ioned -- on t h e d e f l e c t i o n b e h a v i o u r o f r e l n f o l - c e d conc r8e te componen1;s wiLh shy ink - a g e - s e n s i t i v e a g g r e g a t e s i n England -- t h e c r a c k i n g b e h a v i o u r o f b r i c k w a l l s s u p p o r t e d on r e i n f o l a c e d c o n c r e t e components was s t u d i e d by R . H . Wood ( R e f e r e n c e 1 0 ) . Au tho r s Skempton and MacDonald ( H e f e r e n c e l l ) , a f t e r s t u d y i n g 96 f i n i s h e d b u i l d i n g s , r e a c h e d t h e c o n c l u s i o n t h a t p a . r t i t . i o n w a l l damage c o u l d be avoj-ded i f t h e d e f l e c t f o n o r t h e s u p p o r t i n g r e i n f o r c e d c o n c r e t e componerlts i s n o t g r e a t e r t h a n 1/300 o f t h e s p a n . The work p u b l i s h e d by t h e Aner i can S o c i e t y o f C i v 2 l E n g i n e e r s (E.SCE) i n 1961 ( R e f e r e n c e 1 2 ) p u t s t h i s l i m i t i n g v a l u e a t L/500. I n A u s t r a l i a , F . A . Blakey ( R e f e r e n c e 1 3 ) gave t h e p e r m i s s i b l e maximum d e f l e c t i o n f o r a v e r a g e c l i m a t i c c o n d i t i o n s as L/750. A l l a u t h o r s a g r e e , however , t h a t t h e i r l i m i t i n g v a l u e can o n l y be an e s t i m a t e which s t i l l h a s t o be v e r i f i e d by e x t e n s i v e i n v e s t i g a t i o n s . A s a l r e a d y i n d i c a t e d i n S e c t i o n 9 . 2 , i t d o e s n o t a p p e a r r e a s o n a b l e t o p r e s c r i b e a c o n s t a n t v a l u e f o r t h e p r e v e n t i o n o f p a r t i t i o n w a l l c r a c k s . The r e l e v a n t l i m i t i n g v a l u e must d e c r e a s e w i t h i n c r e a s i n g s p a n l e n g t h s .

F o r t h i s r e a s o n a s u r v e y was a l s o i n s t i t u t e d a p p r o x i m a t e l y two y e a r s ago (1965 - T r a n s l a t o r ) i n t h e U.S.A. by Committee No. 435 o f t h e American Concre t e I n s t i t u t e (ACI) w i t h a view t o c o l l e c t i n g and a s s e s s i n g c a s e s o f d e f l e c t i o n damage. The r e s u l t s o f t h i s su rvey a r e u n f o r t u n a t e l y n o t y e t a v a i l a b l e . " I n a d d i t i o n , the Comitc? Europgen du B6ton (CEB) and t h e C o n s e i l I n t e r n a t i o n a l du Bst iment (Ci B) i n t r o d u c e d t h e d e f l e c t i o n problem q u i t e e a r l y i n t o t h e i r d e l i b e r a t i o n s . A summary o f t h e e x p e r j e n c e s i n Europe can be found i n CEB B u l l e t i n No. 16 (Refe rence 1 4 ) and i n C I B (F?efellence 1 8 ) .

1 5 . 3 D e f l e c t i o n L i m i t a t i o n s o f R e i n f o r c e d Concre t e Components I n

Var ious C o u n t r i e s

Comparisons o f d e f l e c t i o n r e q u i r e m e n t s o f r a e i n f o r c e d co r l c re t e b u i l d i r - g components i n v a r i o u s c o u n t r i e s were c a r r i e d o u t i n 1960 by CEB (Refe rence 1 5 ) and i n 1963 by t h e U n i v e r s i t y o f I l l i n o i s (Refe rence 1 6 ) . Consequen t ly , t h e r e i s no need t o make a similar e v a l u a t i o n h e r e . I n what f o l l o w s o n l y a s h o r t su rvey w i l l be g i v e n of notewor thy pr30posa ls f o r l i m i t i n g t h e d e f l e c t i o n o f r e i n f o r c e d c o n c r e t e b u i l d i n g components. According t o t h e r e q u i r e m e n t o f v a r i o u s c o u n t r i e s t h l s l i m i t a t i o n i s a t t e m p t e d by t h r e e d i f f e r e n t means.

F i r s t l y , t h e p e r m i s s i b l e maximum v a l u e s o f d e f l e c t i o n a r e g i v e n . I n g e n e r a l , d e t a i l e d d a t a f o r t h e d e t e r m i n a t i o n o f t h e a c t u a l d e f l e c t i o n s a r e a l s o p r e s e n t e d . The magnitude of t h e p e r m i s s i b l e d e f l e c t i o n v a r i e s between f = L/?OO and L/1000, depend ing on t h e t y p e o f l o a d i n g . The c o u n t r i e s o f COMECON** recommended a c le f l ' ec t ion l i n i i t a t i o n which depends on t h e l i v e l o a d ( R e f e r e n c e 1 8 , page 2 ) . For apa r tmen t s l a b s t h e d e f l e c t i o n due t o dead l o a d s h o u l d be l e s s t h a n R/200 and t h e i n c r e a s e due t o 100 kp/m2 o f l i v e l o a d i s

For dance h a l l s , gymcasia., e t c . t h e p e r r n i s s i b i e v a l u e s a r e t o be h a l v e d .

A second p o s s i b i l i t y f o r t h e l i m i t a t i o n o f d e f l e c t i o n l i e s i n s e t t i n g p e r m i s s i b l e maxima f o r t h e s l e n d e r n e s s r a t i o s o f t h e r e i n f o r c e d c o n c r e t e components. F o r n ~ e r l y f i x e d v a l u e s were chosen; t oday t h e y a r e f r a e q u e n t l y s t a t e d as a f ' unc t ion o f c o n c r e t e and s t e e l s t r e s s e s . The p e r m i s s i b l e v a l u e s a r e g e n e r a l l y g i v e n i n t a b u l a r form. The v a l u e s g i v e n i n t h e addendum t o D I N 1045 c o r r e s p o n d a p p r o x i m a t e l y t o t h e fo rmula :

T r a n s l a t o r ' s Note - T h i s r e p o r t h a s s i n c e been p u b l i s h e d . See "Allowable D e f l e c t i o n s " by R . S. F l i n g e t a l . , A C I J o u r n a l , J u n e 1968, pp . 433-444.

* * T r a n s l e i t o r ' s Note - "Counci l o f Mutual Economic A s s i s t a n c e " c o n s i s t i n g o f t h e S o v i e t Union, B u l g a r i a , Czechos lovak ia , E a s t Germany, Hungary and Poland.

F i n a l l y , a t h i r d p o s s i t ~ i l i t y f o r l i m l t i n g d e f l - e c t i o n i s t o p r e s c r i b e t h e minim~im t h l c k n e s s o f t h e r l e i n f o r c e d c o r ~ c r e t e components . The Comm<ttee A 7 o r t h e Methe r l ands Concre t e Association (CUR) h a s proposed t h e f o l l o w i r ~ g S o r m u l ~ . ( R e f e r e n c e 1 5 , page 81 ) :

t iowe-~er , t h i s a g a i n l e a d s t o a l i m i t a t i o n on t h e s l e n d e r n e s s r a t i o s i n c e t h e above fo rmula may be t raansformed i n t o

k c h a r a c t e r i s t i c f e a t u r e o f a l l new r e i n f o r c e d c o n c r e t e codes i s t h a t two- way r e i n f o r c e d concreA;.e s 1 l e . b ~ mn.y riot be s l e n d e r e r t h a n one-way s] a b s . An i n t e r e s t i n g p r o p o s a l f o r d e t e r m i n i n g t,he minimum t h l c k n e s s o f s u c h s l a b s has been advanced i n t h e U.S.A.:

. c i r c u m f e r e n c e do 2 180 L - 9 cm

Swederl i s t l ~ e on ly c o u n t r y which s o f a r h a s int ; roduced a s p e c i a l requLremtznt r e j nf orced c o n c r e t e s l a b s s u p p o r t i n g p a r t i t i o n walls . The t h i c k n e s s o f such s l a b s s h o u l d be :

> /7M-- do = p e r m i s s i b l e ubz [ k p , cm!

As was a l r e a d y rzent loned, t h i s formula. s h o u l d g u a r a n t e e t h a t t h e r e i n f o r c e d c o n c r e t e b u i l d i n g c o m ~ o n e n t s remain i n S t a t e I .

1 6 . SUMMARY

( 2. ) t o e x c e s s i v e def been d e s c r i b e d . M a t e r i a l T e s t i n g Munich, i t 1 t h e t, 1 8 1 c a s e s o f b u i e v a l u a t e d accord

A s t a t i r t i c a l c o l l e c t , i o n o f c a s e s o f b u i l d i n g damage due ' l e c t l o n s o f re inforaced c o n c r e t e b u i l t l i n g components h a s

The sui-vey was c a r r i e d o u t from 1960 t o 1965 by t h e Labora to ry I'or S t r l l c t u r e s o f t h e T e c h n i c a l U n i v e r s i t y ,

e r r i - t o r j o f t h e Fede~aal R e p u b l i c o f Germany. A l t o g e t h e r l o i n g damage were r e p o r t e d . They were p r o c e s s e d and i n g t o uni form c r i t e r i a .

( b I t was shown t h a t t h e dange? o f damage grows s u b s t a r l t i a l l y w i t h i n c r e a s i n g e x p l o i t a t i o n of b u i l d l i n g m a t e r i a l p r o p e r t i e s and w i t h t h e e x e c u t i o n o f e v e r more s l e n d e r b u i l d i n g components .

( c ) The f o l l o w i n g t y p e s o f damage o c c u r r e d i n o r d e r o f t h e i r : importance :

P a r t i t i o n wall craclcs Exc:essl ve s l a b d e f l e c t i o n Cracks i r ~ r e i n f o r c e d c o n c r e t e components

H o r i z o n t a l c r a c k s i r ~ bi ' ick wol-k i n t h e v i c i n i t y o f s l a b s u p p o r t s P l a s t e r and finishing damages O t h e r s

( a ) Gamage was most f r e q u e n t l y o b s e r v e d i n two-way r e i n f o r c e d p l a t e s and r i b b e d s l a b s .

( e ) The p a r t i t i o n w a l l c r a c k s a r e ma in ly a consequence o f y i e l d l n g s u p p o r t s due t o h i g h l y f l e x i b l e r e i n f o ~ c e d c o n c r e t e s u p p o r t members, s i n c e t h e i r d e f ~ r m a t ~ i o n increases w i t h t i m e due t o c r e e p and s h r i n k a g e of' t h e c o n c r e t e . The damage c o u l d be p r e v e n t e d by a r e d u c t i o n o f t h e s l e n d e r n e s s r a t i o o f t h e s u p p o r t i r ~ g reinf'o:>ced c o n c r e t e member t o t h e v a l u e

o r tjy means of a n a p p r o p r i a t e d e s i g n o f t h e p a r t i t i o n w a l l i t s e l f . P o s s i b i l i t i e s f o r s u c h d e s l g n s were i n d i c a t e d i n S e c t i o n 9 .

( r ) Excessive s l a b d e f l e c t i o n s we1.e c a u s e d by many e r r o r s . The e v a l u a t i o n showed t h a t a d e f l e c t i o n o f up t o

i s lrot found t o be d i s t u r b i n g t o t h e naked e y e . With a form-work camber of L/300, a v e r a g e c r e e p and sh r i r , kage b e h a v i o u r o f t h e c o n c r e t e ( 4 = 3, E = 0 .30%) , norm21 p e ~ m a n e n t l o a d r a t i o ( q /q = 0 . 7 5 ) and dimensionTng a c c o r d i n g t o D I N 1045 , e x c e s s i v e s l a b g e f l e c t i o n need n o t be e x p e c t e d a t s l e n d e r n e s s r a t i o s up t o 35.

( e l A l l o t h e r damage c o u l d b e t r a c e d e s s e n t i a l l y t o e r r o r s o f d e s i g n and workmanship. These were t a k e n up i n d i v i d u a l l y i n S e c t i o n s 11 t o 1 4 and s u g g e s t i o n s f o r improvement were made.

( h ) F o r c a s e s where i d e n t i c a l . s t r e s s and s l e n d e r n e s s v a l u e s were i n use, %he same d e f l e c t i o n damages o c c u r r e d i n f ' o r e ign c o u n t r i e s as h e r e . S y s t e r n a t i c i r ~ v e s t i g a t i o n s r e g a r d i n g ' ~ a r i o u s s p e c i f i c p o s s i b i l i t i e s of damage were c a r r i e d o u t i n England and A u s t r a l i a . Damage a n a l y s e s o f t h e k i n d i n d i c a t e d h e r e have been i n i t i a t e d i n t h e U.S.A., Belgium, Poland and B u l g a r i a .

FIGURES 1 TO 46

and

TABLE I

( T r a n s l a t o r ' s Note : No F i g u r e 2 2 a p p e a r e d

i n t h e o r i g i n a l t e x t )

Figure 1: Region covered by the damage survey.

Questionnaire of Technical University Munich

pr Questionnaire of BStG-Gmb H Diisseldorf ) No damage

+ One o r m o r e cases of deflection damage

Figure 2: Freqency of reported build-

ing damage (the meanings of de signa-

tions along the absc issa can be found

i n the text o r in the Lis t of Symbols,

Section i).

LalblclcllrIfl LdEHEDJ mtrd7im Bczrichnung : kc du. du kr: KC

Designation

Figure 3: Frequency of types of building

components which exhibited building

damage (the meanings of designations

along the absc issa can be found in the

L i s t of Symbols, Section h).

Figure 4: Frequency of types of

building components with

s lenderness rat ios l e s s than

35 which exhibited building

damage.

Arbi t rary b e a p : I

I

Figure 5: Geometric interpretation of

the definition of equivalent span

length Li of a beam subjected to

Substitute o r a rb i t r a ry loading.

Equivalent beam

!

Figure 6: Elaboration of the

approximation formulae for the

coefficient k in the equivalent

span length (the moments a r e to

be substituted in the formulae

with due regard to sign).

F igure 7: Coefficient k fo r the

equivalent span length of plates

supported on four sides o r

comparison of the deflection

behaviour of plates supported on

two sides with those supported

on four sides.

Geometrical GEOM. S ~ U ~ Z W E I ~ E N E R S A T Z - s r i i r z w ~ ~ ~

Span Lengths Equivalent

Span Lengths

Figure 8: Example for the deter - - I [,i= 0.80I.

mination of the governing ( &yeYk s )

deflection slende rne s s ratio of

a plate supported on four sides. 1 - I , , ,- ,,---L

Figure 9: Frequency of observed

causes of damage (the meaning

of designations along the abscissa

can be found in the text o r i n the

Lis t of Symbols, Section k).

sioning tion ship

Figure 10: F i r s t category of parti t ion

wall damage: gaping c racks between

wall and floor due to a self-supporting

wall.

F igure 11: Second category of parti t ion I

wall damage: c racks a t the joint

between wall and ceiling and towards

the exter ior wall due to rotation o r

movement of individual wall plates . - -- - - -- - --- -- - - -- -- - ----

Figure 12: Third category of partition

wall damage: Step-like inclined

cracks in the wall due to excessive

shear s t resses .

Figure 13: Fourth category of partition

wall damage: Vertical cracks in the

wall due to excessive flexural

s t resses .

.. ~ ~ ~~~ . .- - .. -. . ~- ~- 1 Gap between

Cracks

Figure 14: The various categories of partition wall damage a s a

function of the span.

x alsm. inn.rh&lb i.r . . n l i ~ i . a c h . ' oB, ...- .. ,chubrl.. . ,. .... : t, RLer.rl.ur -- , I.t unb.r.nnr. - - -

- - m Gap between wall and floox 1 A Cracks between wall and ceiling

_ x Cracks within

0 Bending and s

C r a c k pat ternj is unknown

x Cracks within thb wall a r e a

0, Beqding, and, she r cqackg in the yrall ~t

o k I I 1 I - o 5 10 i s min 1, (ml

0 0 s 10 1s rnin li ( m )

n Crack pat tern i s unknown

Figure 15: The theoretically determined deflection, which

presumably caused the initiation of partit ion wall damage.

Members which were analysed cor rec t ly and built a s planned

o Calculation e r r o r s

+ E r r o r s in workmanship

x Design e r r o r s

Figure 16: Limiting s lenderness rat io of reinforced building components

for the prevention of partition wall damage. This i l lustrat ion gives

the relationship between the s lenderness ra t io and the span of reinforced

concrete carrying m e m b e r s with partit ion wall damage. I t i s presented

a s a function of the causes which were mainly responsible fo r the la rge

deflection.

Members which were analysed cor rec t ly and built a s ~ l a n n e d

o Calculation e r r o r s

+ E r r o r s in workrnanship

x Design e r r o r s

Cause of damage unknown

F igure 17: Measured values of s lab deflections which were found objectionable.

Members which were analysed correc t ly and built a s planned

o Calculation e r r o r s

+ E r r o r s in workmanship

x Design e r r o r s

Cause of damage unknown 0-am

. . . - - - ~~ ~ -- ~ ~

~ ~ - .~ - --

x+

+ 0 +

qo,o- . .- m- -- --

+ x X 0

+ + 0

+

L , L I 300 - . - . - . - . - . - . - - . -

0 I I 1 I

o 5 10 15 ii

Figure 18: Limiting values of deflections of reinforced concrete building

components fo r the prevention of an objectionable ceiling deflection. -

The il lustration shows the relation between the deflections measured

on s i te and the span of the loaded member .

F igure 19: Effect of s lenderness ra t io

on the s ize of the deflection of a

normal reinforced concrete s lab in a

building, with a formwork camber of

f;; = ~ / 3 0 0 . In the shaded a r e a ,

objections to the deflection can be

expected.

-. Formwork camber ffi

Figure 20: Effect of the continuously acting

load component qd of the total load q

on the deflection magnitude of the slab

of Fig. 19.

variable,

Figure 21: Effect of creep and shrinkage

deformation of the concrete on the

deflection magnitude of the slab of

Fig. 19.

Dimensions and Statical System ---.A

Abmessungen u n d ' s l a t S y s t e m

a ~ n - n m o u ~ r t E x t e rio r Wall

Slab

,ete t ie beam

I Cross Section Y - Y w f R % N I T r Y - Y

\ /

C l # f C j ldlp in jeder zweiten R ~ p p e 1st

5 0 4 dos Elsen oufgebogen. ZI

Steel i s bent up in every second r ib.

Figure 23: Crack in the top surface of

a ribbed slab at the end of the solid

edge s t r ip o r a t the edge of the

support edge beam (Case No. 19).

Suite A Suite B

I Wohnung A t wa*nung 6 I

F igure 24: Cracks in the top surface of

a reinforced concrete s lab along a

supporting wall that i s unnecessary

f rom the standpoint of statics.

Dimensions and Statical System

Abmrssungen und stat . System

Aufge l re tener Schaden Observed Damage

r l e Drlllbewehrung

Because of

absence of

Figure 25: Diagonal cracks in the top surface of

a reinforced concrete slab supported on four s ides

(Case No. 123) .

I I 0s t w a n d E a s t wall

w e 4 mm x 'X ,F Top F a c e of Slab

/

- -.< \

Stahls te indecke d =32 c m \

C Westwand West wal l U -.-- ~ -. . ~ 16 4 1 - . .. --4 *

Section:

Observed Damage A u f g e t r e t e n e r S c h a d e n ---

Osf w a n d E a s t Wall k + 4 6 5 - -A --------- -------

South Wall

-

Slab Support

F igu re 26: Horizontal c r a c k s in the ex te r io r s tucco within the

ceiling s lab support (Case No. 140).

I '

I .>I Figure 27: Horizontal c rack in the -------

t exterior stu'cco beneath the slab ~.~+ .*~:, -. "- --' --A . ~ . ~ --_ support due to edge rotation.

lm Aunrnpulz

Horizontal

Crack in

Exterior plaster '--- .

Apparent d 8

Movement of Cd(

Figure 28: Horizontal c rack in the

exter ior stucco above the slab

support between wall plate and

roof plate due to edge rotation

of the raised edge beam.

(Horizontal Crack in Inter ior f W /Uff izonl~ lr tn r r n l n n r n p v l r )

P l a s t e r )

Figure 29: Horizontal c r a c k in the

inter ior p las ter due t o edge

rotation of the raised edge beam

4 C1

I

Figure 30: Objectionable moven~er l t

- . . of the baseboard due to edge

' . . A, - " - - - d l

rotation of s l ab support .

rm Aunrnpulr

Crack in

Horizontal

Ex te r io r P l a s t e r

HorizontalrifJ im lnnenpulz

Horizontal C r a c k in In t e r io r

P l a s t e r

- - - .- 1 2 > ( ! . . - . . / - - - - 1

Figure 31: C r a c k format ion in the i n t e r io r p l a s t e r owing to rotation of a

continuous s l ab with grea t ly different spans o r loadings.

F igu re 3 2 : Raising of c o r n e r s of

a s l ab supported on four s ides

under insufficient load and/or

absence of c o r n e r anchorage.

~ o ; r z o n f o l r r s s e ,rn Eckberelch - i

Horizontal C r a c k s a t the C o r n e r s

Figure 33: Horizontal c r ack in the co rne r region of a reinforced

concrete plate supported on four s ides due to insufficient load

and absence of co rne r anchorage.

F igu re 34: Spalling of wall p l a s t e r due to

unsuitably de signed joint a r rangement

in the reinforced concrete slab. bplatzuog

P l a s t e r Crack and

Spalling

Shear Cracks in the C r o s s Rib

F igu re 35: Spalling and cracking of Schubrfsse rn der Cluerrfppc

ceiling p l a s t e r in the vicinity of

the wall owing to rigidity of the

one-way ribbed s lab along the

wall para l le l t o the span.

49 Sutnme r WINTER SOMMER T. = - 2 0 4

I

P l a s t e r

s tucco P l a s t e r 7;=+200

Figure 36: Effect of thermal insulation on the tempera ture change in a

reinforced concrete slab. The difference A t m a y be viewed a s a

m e a s u r e of the maximum change in slab deflection which i s to be

expected during any one year . (Al l t empera tu res , T , a r e given in

degrees C . )

Footnote: :k2:: Heraklith = Trade name f o r boards of cemented wood f ibres .

O,3 Brlog Tiling ,<3,5 Eslrlch

,, ,,,y,t, o ~sot i r rung Flooring , I, 0 pusglrichschichl

Insulation

,- , ,,,,A'/ Finishing Layer

P l a s t e r Crack P las t e r Crack

Figure 37: Unintentional support of a pre-cas t ceiling s lab on a parti t ion

wall paral lel to the span of the slab.

C r o s s Section Q U F R 5 C H N I l l

Figure 38: Separation of a false ceiling 1 Suspended ;,n~;","c$k

Ceiling a t the cantilevered reinforced con-

.+ ~~ ~

I 5.00 c re te plate with p las ter c rack a t the f r ee cantilever edge. The false

ceiling and the concrete s lab were

rigidly connected without any

expansion joint a t the f r e e end. As

the cantilever plate deflected, the

p las ter sheared off the plate.

P l a s t e r Crack

Figure 39: Buckling phenomena in the

ceiling p las ter o r spalling of l imited

p las ter regions owing to unintentional

support of the two wall plates (dotted

a r e a s ) on the acoustical tile o r the

plaster supports. stauchund dar ~challdammplatter

( 1 b j k k l e n e ~ n z e n e ~ u t z t e l l e )

uc ing o i A c o u s t ~ c a l 1 -- --- -- --

Tile (Spalling of individual

P l a s t e r P ieces )

shop' Window

R i b l i e d 7" Slab

f ; p f l e n d ~ ~ hi! A = ::= .--=

Figure 40: Fa i lure of a show window owing to insufficient to lerances

between the glass and the reinforced concrete g i rde r ( see Ref. 8).

. . . . . -. $ j o ~ ~ - . .. .- -. $57 -

. .. . - ,6,9,+ . . . . - - -- - -

St i r rups Column Section , Section 1 - 1 5f"tze-GrundriD I

Schniff 1- 1

Detail- R~ppendecke x 200 mm Detail of Ribbed Slab verschw. ~ o o . ~ o o m m

welded together

F igure 41: Reinforced concrete ribbed slab supported on s tee l columns.

Owing to c reep and shrinkage of the concrete , the edge rotation a t the

support and consequently the f lexure of the s teel columns increased

to such an extent that a collapse of the ceiling was feared.

C Scale M e s s u r e n ~ e n t s

# = I : 100 #ane i n c m

SUPEN Section South

~ X n i t t

Roofing 2 l a y e r s t a r pa Dachdeckung 2 1 a g e n Pappe / B / m r r t e g d l e l l ! n 8 c m

Light-weight p r e c a s t

s t r i p s 8 c m

wood f ib re board 15 cm Kalkgipsputz

1.5 cm Scholldammplatt

Uz in Nr. 108 g e k l r b t A $. Sound insulation board glued withUuzin No. 108. "

F i g u r e 42: Forma t ion of dep res s ions i n a f la t roof owing t o excess ive

deflection of the re inforced concrete slab. In the c a s e No. 119

shown, gaping horizontal c r a c k s appeared a t the f ront of the

building owing to the edge rotation of the re inforced concre te beam

F u r t h e r m o r e , some of the glued acoust ical t i l e s fe l l f r o m the ceiling

of the i n t e r io r room. In the inspection r epo r t i t was assumed that

water had collected in the hollows of the roof. Th i s led t o wa te r

penetration of the roofing, sa turat ion of the concre te s l ab and l o s s

of adhesion of the glue.

C o r n e r Lifted 'Nith bolts fckemilSchrauben I -Beam "IPlb"

angehoben /P16 - L R e m o r a g e

D e f l e c t i o n Y ~ i e ~ e f i n i e - ~ ~ . "

Curve ~ra~dachf

c, Ecke

Canti lever ~ o o f 1 - 1 I I

C o r n e r

F igu re 43: Rever sa l of the intended slope of a cant i lever roof owing

t o excess ive deflection ( see Ref. 8).

Section + Schnl t t 1-1

ion Joint

A u t g e t r e t e n e r Schoden -> Observed Damage

Deflection up to 4 c m

F i g u r e 44. Excess ive ver t ica l movement n e a r an expansion joint of

a folded roof because the re inforced concre te she l l on the right i s

substantially s t i f fer than the t rough plate on the left .

F r o n t View A n s l c h t ~7

Aluminum Curta in Wall

1 e i c h t m e t a I I f a s s a d e C'

Dimensions in C r o s %tion +7 Mane in m T u e r s c h n , ? t

---'

I - - _ -- - ~ ~ ~ r ~ ~ ~ ~ ~ ~ ~ ~ r ~ r ~ ~ ~ ~ ~ r--- -- ---- - I rr-- --7

F i g u re 45: Jamming of windows of the at tached

aluminum cur ta in wall owing to d i f ferent ia l

deflection of the long cant i levered re inforced A b m e s s u n g e n d e r 4. O G - D e c k e -, concrete s labs . Dimensions of 6th Storey F loo r Slab

Section 2.

Schni t t 1-L

C r a

Ri I3

Stat ical Svs tem of the F loo r Slab

,/;5+.. f -4-

,,:,.4. .. 'x . .. .

--- d ?-' ,'

,--;/ \..:,... . '-. , " ,

s t a t . ~ y s t e ; n d e r Geschofldecke C- ' --t

j . 0 ~ -7 2nd Storey

D e t a i l I A

D e t a i l 2 -

.I-:

2nd Storey Ceiling , Slab - without

1.OG Decke ohne Dr i l l bewehrTng T g r ion it- u n d K t - D e c k e mi t D r i l l b e - Reinforcement w e h r u n g

1 s t S torey and Basement Ceiling

I Slabs with Tors ion Reinforcement

EG-'1 s t s t o r e y Steel S t raps used a s additional support

2- '> B a n d e i s e n o l s r u s d l z l i c h e f o r bathroonl

. Hol le rungen fur die Bode - z e l l e n

. .

Insulation , . , , , , ,'

1 T I -

Deflecti Durchbiegung

..:'7--7 7- ' T

, ,~,,.~,,~,~,.

F i g u r e 46: Bending of the s t ee l s t r a p s of bathroom parti t ion wal ls in the

basement , and horizontal c r a c k in the ex t e r io r s tucco beneath the

bear ing of the a t t ic s1a.b.

par t i t ions

- I

.

r I 1

-

I)

18. REFERENCES

1. Riisch, H. and Mayer, H. "Die zeitliche Entwicklung der Durchbiegung von ausgefuhrten Stahlbeton-Traggliedern". (The Time-Dependent Deflection Development of Erected Reinforced Concrete Load Carrying Members). Beton-und Stahlbetonbau, Heft 10/1964, pp.224-230.

2. Mehmel, A. "Uber eine sinnvolle Beschrhkung der Durchbiegung von Stahlbetonbauteilen". (On a Meaningful Deflection Limitation of Reinforced Concrete Building Components). Der Bauingenieur, Heft 8/1961, pp.293-300.

3. Mayer, H. "Die Berechnung der Kurzzeit- und Langzeitdurchbiegung von Stahlbetonbauteilen im Stadium I und 11". (The Calculation of the Short-Term and Long-Term Deflections of Reinforced Concrete Building Components in State T and State 11). Dissertation TH Mtinchen, 1965 (published under "Die Berechnung der Durchbiegung von Stahlbeton-bauteilen", Deutscher Ausschuss fur Stahlbeton, Heft 194,

1967) * .

4. CEB "Recommandations pratiques unifiges pour le calcul et llexc?cution

des ouvrages en b6ton armg". CEB Publication 1964 Comit6 Europgen

du Bgton, Paris XVI, 9, Rue la Pgrouse.

5. Hilfsdorf, H. "Bewehrtes Ziegelmauerwerk - Literatursichtung". (Reinforced Brickwork - Literature Survey). MaterialprUfungsamt fGr das Bauwesen der Technischen Hochschule MSnchen.

6. Robenhagen, G. "Schwere Schaden im Wohnungsbau bei Ausfthrung iiblicher Vollbetondecken und Wege zu ihwrVermeidung1'. (Major Damages in Building Structures with Common Solid Concrete Slabs, and Ways of Preventing Such Damage 1. Der Bau, Heft 12/1957, PP. 350-353-

7. Hartmann, M. "~ochbausch~den und -FehlerM. (Structural Damage and Errors). Taschenbuch, Franckh'sche Verlagshandlung Stuttgart, 1964.

8. Franz, G. "SchSden infolge zu grosser Durchbiegung und ihre Gegenmassnahmen". (Damage Due to Excessive Deflection and Counter- measures). Zement und Beton, Heft 21, April 1961.

9. Jenkins, R.A.S., Plowman, J.M. and Haseltine, B.A. "Investigation Into the Cause of the Deflexion of Heated Concrete Floor Including Shrinkage". The Structural Engineer, April 1965, No.4, Vo1.43, and Disc. in Sept. 1965, No.9, Vo1.43.

10. Wood, R.H. "Studies in Composite Construction, Part I: The Composite Action of Brick Panel Walls Supported on Reinforced Concrete Beams".

Gt. Britain, D.S.I.R., National Building Studies, Res. Paper No.13 1952, 25 PP.

11. Skempton, A.W. and MacDonald, D.H. "The Allowable Settlement of Buildings". Journal I.C.E., Vo1.5, Dec.1956, pp.727-784.

* Translator's Note

12. American Society of Civil Engineers - Committee on Masonry and Reinforced Concrete - Reinforced Masonry and Practice. Proc. A.S.C.E., Journ. Struct. Div., Vo1.87, No.518, Dec.1961, pp.87-138.

13. Blakev, F.A. "Deflection as a Design Criterion in Concrete ~uildin~s", Civil Engineering ~ransact ion of the Ins ti tution of

Engineers, Australia, Vol. CE 5, No.2, Sept.1963, pp.55-60.

Blakey, F.A. "The Deflection of Flat Plate Structures". Civil , 8 Buckingham Street, London, Vo1.58, 1963, N=,

Blakey, F.A. "Australian Experiments with Flat Platestt. ACI Journal, Proc. Vo1.60, April 1963, p.515.

14. Soretz, St. "Deformationen - Kommission Nr. 4a1'. Comite Europeen du B6ton (CEB), Bulletin No.16, Mar.1959, Paris XVI, 9, Rue la Perouse .

15. CEB. llDalles - Planchers-Dalles - Commission No.10". Comite ~ u r o ~ g e n du ~ 6 t o n (cEB), Bulletin No.29, Nov.1960, Paris XVI, 9, Rue la Perouse.

16. Vanderbilt, M.D., Sozen, M.A. and Siess, C.P. "Deflections of Reinforced Concrete Floor Slabs1', Ci~il~Engineering Studies, Structural Research Series No.263, University of Illinois, April 1963.

17. Rao, P.S. "Die Grundlagen zur Berechnung der bei statisch unbest- immten S t a h l b e t o n k o n s t r u k t i o n e n im plastischen Bereich auftretenden Umlagerungen der Schnittkrgften. (The Bases for the Calculation of RedistributLon of Internal Forces in the Plastic Range in Statically Indeterminate Reinforced Concrete Construction). Dissertation TH Mcnchen, 1965, published by Deutscher Ausschuss fur

Stahlbeton, Heft 177/1966.

18. Mathez, J. tlRapport provisoire relatif aux d6formations admissibles des planchers". Centre Scientifique e3 Technique du B$timent, (CIB), Oslo, August 1965, ~ h s m e 7.

LIST OF SYMBOLS

Loads a ) -

G P o i n t o r l i n e l o a d due t o dead l o a d

P I'oint, o r l l n e l o a d due t o l i v e l o a d

8 Uniform l o a d due t o dead l o a d

Uni i 'o~~m l o a d due t o l l v e l o a d ; a c c o r d i n g t o D I N 1055, P a r t 3 , u n l e s s o t h e r w i s e s t a t e d

d Uniform l o a d due t o t h e c o n t i r ~ u o u s l y a c t i n g l i v e l o a d

9 Uni fo rn load due t o dead l o a d and l i v e l o a d

b ) S t r e s s e s

G b

S t r e s s i n conc lae t e a t t h e compress ion edge o f t h e c r o s s s e c t i o n

e S t r e s s i n s t e e l of t e n s i l e r e i n r o r c e m e n t

" d. S t r e s s i n s t e e l o f compress ion r e i n f o r c e m e n t

c j S t r a i n s and Young's Nodulus

0 S t r a i n a t compl'ession edge o f c r -oss sec:tiorl ( compress ion n e g a t i v e )

E S t r a i n a t a x i s of t e n s i l e ~ > e i n f o r c e m e n t ( t e n s i o n e p o s i t i v t . )

Sum of edge s t r a i n s

Curva tu re o t a beam s e c t i o n

D e f l e c t i o n ; a t beam c e n t e r l i n e , u n l e s s o t h e r w i s e s t a t e d

R c t a t i o n of bean a t end s u p p o r t A

Angle of i n c l i n a t i o n uf t h e t a n g e n t t o d e f l e c t i o n c u r v e

Gap i n a j o i n t o r v e r t i c a l d i f f e r e n t i a l movemerlt be tween two cros:; s e c t i o n edges

Crac:k wiclth

Modulus of e l a s t i c i t y c f c o n c r e t e

Modulus o r e l a s t i c ' t y of s t e e l

~ c h D e r l e c t i o n which i n i i i i a t e s damage ( f o r d e f i n i t i o n o f t h i s magni tude , s e c S e c t i o n 7 ) .

d ) S t r e n g t h s

Bw Compressive s t r e n g t h o f c o n c r e t e

Bb z F l e x u r a l t e n s i l e s t r e n g t h o f c o n c r e t e

B C o n c r e t e s t r e n g t h s p e c i f i e d f o r c o n s t r u c t i o n

BS, B0.2 E l a s t i c l i m i t o f m i l d s t e e l and c o r r e s p o n d i n g l i m i t o f p r o p o r t i o n a l s t r a i n o f co ldworked s t e e l , r e s p e c t i v e l y .

e ) Dimensions

R Span o f t h e r e i n f o r c e d c o n c r e t e member ( = L - T r a n s l a t o r ' s No te )

E q u i v a l e n t s p a n l e n g t h o f t h e r e i n f o r c e d c o n c r e t e member ( s e e S e c t i o n 6 f o r d e f i n i t i o n ) ( R . = k R )

3

T o t a l p l a t e t h i c k n e s s

Height o f beam

Web t h i c k n e s s

P l a t e w i d t h

E f f e c t i v e d e p t h ; d i s t a n c e from compress ion edge t o a x i s o f t e n s i l e r e i n f o r c e m e n t

Fe, F; C r o s s s e c t i o n a l a r e a o f t e n s i l e r e i n f o r c e m e n t o r compress ion r e i n f o r c e m e n t , r e s p e c t i v e l y

v , P t R e l a t i v e p e r c e n t a g e o f r e i n f o r c e m e n t

L A s f a r as can be d e t e r m i n e d by t h e t r a n s l a t o r , L and

f ) C o e f f i c i e n t s R a r e u sed i n t e r c h a n g e a b l y

-

g ) I n d i c e s

I

I I

D e f l e c t i o n c o e f f i c i e n t which depends on t h e s t a t i c a l s y s t e m , t h e l o a d d i s t r i b u t i o n and t h e c r o s s s e c t i o n a l p r o p e r t i e s . Fo r t h e c e n t e r l i n e d e f l , e c t i o n o f a s imp ly s u p p o r t e d g i r d e r unde r a u n i f o r m l o a d and c o n s t a n t moment o f i n e r t i a t h e v a l u e o f c i s 5/48, f o r example .

Creep c u r v a t u r e c o e f f i c i e n t

C o e f f i c i e n t o f c r e e p f o r c o n c r e t e

S h r i n k a g e c u r v a t u r e c o e f f i c i e n t

S h r i n k a g e s t r a i n o f c o n c r e t e

S t a t e I; unc racked beam s e c t i o n

S t a t e 11; c r a c k e d beam s e c t i o n

Measured i n x - d i r e c t i o n

Y Measured i n y - d i r e c t i o n

h ) E f j n i t i o n s o f Lettering Schemes o f B u i l d i n g Component Types

a S o l i d s l a b s

b Ribbed s l a b s

c P r e - c a s t s l a b s

d Light -weight s l a b s

e R e c t a n g u l a r beams

T-beams

C o n t i n ~ i o u s

Two-way r e i n f o r c e d

Cant i l e - ~ e r

i ) D e f i n i t i o n s o f t h e Numbering Scheme f o r Damage P o s s i b i l i t i e s

1 Cracks i n s u p p o r t e d p a r t i t i o n walls

2 Gaping c r a c k between w a l l and f l o o r o r c e i l i n g

3 Jammed d o o r s o r windows

4 C o l l a p s e o f a p a r t i t i o n w a l l

5 Water s a t u r a t i o n o f a c r a c k e d w a l l

6 E x c e s s i v e s a g g i n g o f a s l a b

7 Forma t ion o f d e p r e s s i o n s , a c c u m u l a t i o n o f w a t e r and l e a k a g e o f c o v e r

8 P l a s t e r c r a c k s o r s p a l l i n g o f i a d i v i d u a l p l a s t e r - p i e c e s

9 Finish i r - ig damages

S l a n t i n g f u r n i l l u r e

F a i l u r e s o f show-window g l a s s

Windows j a m i n an a t t a c h e d c u r t a i n w a l l

Annoying gap i n an e x p a n s i o n j o i n t

Cracked and l e a k i n g g l a z e d t i l e s t o v e s

D i s t u r b i n g v i b r a t i o n phenomena a r e f e l t

H o r i z o n t a l c r a c k s i n b17ick work unde r o r o v e r s l a b suppo? t s

L a t e r a l d e f l e c t i o n o f columns due t o s u p p o r t r o t a t i o n

1 8 Cracks a t t o p s u r f a c e o f s l a b a l o n g t h e l i n e o f s u p p o r t o r a l o n g t h e s o l i d edge s t r i p

1 9 Cracks i n s l a b c o r n e r s normal t o t h e d i a g o n a l

2 0 I n c o m p a t i b i l i t y be tween s l a b d e f o r m a t i o n and r e s t r a i n t s

k ) D e f i n i t i o n s o f t h e Numbering Scheme o f Damage Causes

D e f i c i e n c i e s i n A n a l y s i s

I S l e n d e r n e s s r a t i o Ri/h > 35

Defo rma t ion b e h a v i o u r u n d e r e s t i m a t e d b e c a u s e a n a l y s i s was c a r r i e d o u t a c c o r d i n g t o S t a t e I

D e f o r m a t i o n a l b e h a v i o u r u n d e r e s t i m a t e d b e c a u s e c r e e p and s h r i n k a g e o f c o n c r e t e was n e g l e c t e d

R e d i s t r i b u t i o n o f i n t e r n a l f o r c e s n o t c o n s i d e r e d owing t o n e g l e c t o f c r e e p and s h r i n k a g e o f c o n c r e t e

E r r o r s ir. C a l c u l a t i o n

V I Ord ina ry c a l c u l a t i o n e r r o r

V I I S t a t i c a l sy s t em d o e s n o t c o r r e s p o n d t o r e a l i t y

V I I I T o r s i o n a l s t i f f n e s s o f a two-way s l a b was a c c o u n t e d f o r w i t h o u t j u s t i f i c a t i o n

I X Founda t ion s e t t l e m e n t was n o t a d e q u a t e l y considered

X Load a s s u m p t i o n s a r e t o o f a v o u r a b l e

E r r o r s i n Workmanship

X I P r e s c r i b e d c o n c r e t e s t r e n g t h was n o t a t t a i n e d

X I 1 R e q u i r e d amount o f r e i n f o r c Z n g was n o t i n c l u d e d

X I 1 1 Heigh t o f r e l n f o r c e m e n t was n o t o b s e r v e d i n a c c o r d a n c e w i t h t h e p l a n s

X I V S o l i d edge s t r i p t e r m i n a t e d t o o e a r l y

XV Formwork w a s manufac tu red i m p r o p e r l y

Design E r r o r s

X V I Rein fo rcemen t t o r e s i s t u n i n t e n t i o n a l r e s t r a i n t s was a b s e n t o r s t o p p e d t o o s h o r t . T o r s i o n a l r e i n f o r c e m e n t was a b s e n t

X V I I Damage-free defor -mat ion o f t i l e r e i n f o r c e d c o n c r e t e component was n o t p e r m i t t e d

X V I I I S h r i n k a g e - s e n s i t i v e b r j c k w o r k was e r e c t e d

XIX

xx

P a r t i t i o n w a l l s a.re c a r r i e d by r e i n f o r c e d c o n c r e t e members

S u p p o r t s f o r c o n c r e t e components were d e s i g n e d t o o f I e x i b l e

APPENDIX

20. SET OF TABLES OF THE MOST IMPORTANT DATA ON EACH INDIVIDUAL CASE

O F DAMAGE

The f o l l o w i n g t a b l e s c o n t a i n t h e most i m p o r t a n t d a t a which c h a r a c t e r i z e t h e r e i n f o r c e d c o n c r e t e components t h a t c o n t r i b u t e d t o t h e v a r i o u s c a s e s o f damage. The d a t a were d e r i v e d from t h e borrowed form- work and r e i n f o r c i n g p l a n s , s t a t i c a l c a l c u l a t i o n s o r from i n s p e c t i o n r e p o r t s . I n a d d i t i o n , columns 1 8 t o 25 g i v e some r e s u l t s o f c a l c u l a t i o n s from t h e e v a l u a t i o n s t h a t were c a r r i e d o u t .

The meanings of a l l symbols used i n t h e T a b l e s , i n c l u d i n g t h e l e t t e r i n g and numbering schemes, can be o b t a i n e d from t h e L i s t o f Symbols. I f t h e l e t t e r B a p p e a r s i n f r o n t o f t h e numer ica l v a l u e o f t h e c o n c r e t e s t r e n g t h (column 1 0 ) t h i s means t h a t o n l y t h e s p e c i f i e d c o n c r e t e s t r e n g t h cou ld be o b t a i n e d from t h e documents. Without a l e t t e r p r e f i x t h e v a l u e s s i g n i f y t h e r e s u l t s of compress ion t e s t s . Where no v a l u e a p p e a r s i n a column of a l i n e , i t means t h a t t h e v a l u e cou ld no t be o b t a i n e d from t h e a v a i l a b l e documents.

The i n d i v i d u a l c a s e s o f damage were p r e s e n t e d i n a system- a t i c manner. F i r s t t h e c a s e s o f p a r t i t i o n w a l l damage were g i v e n i n t h e o r d e r of e q u i v a l e n t span l e n g t h min. R . Second, s t a r t i n g from c a s e No. 92, o b j e c t i o n s t o e x c e s s i v e s l a b d e f l e A t i o n s were g i v e n where no p a r t i t i o n w a l l damage had o c c u r r e d s i m u l t a n e o u s l y . These c a s e s were a g a i n a r r a n g e d a c c o r d i n g t o t h e e q u i v a l e n t span l e n g t h . S i m i l a r l y , s t a r t i n g from case No. 133, we have h o r i z o n t a l c r a c k s i n t h e v i c i n i t y o f s l a b s u p p o r t s ; from c a s e No. 1 4 4 , c r a c k s i n t h e r e i n f o r c e d c o n c r e t e component; and from c a s e No. 154, o c c a s i o n a l d e f l e c t i o n damage w i t h a d e f i n a b l e r e a s o n f o r t h e compla in t . F i n a l l y , from No. 163 on, i t i s known on ly t h a t a d e f l e c t i o n damage had o c c u r r e d .

T r a n s l a t o r ' s Note: There a r e two d i f f e r e n t damage c a s e s No. 119 . This a p p a r e n t c o n f l i c t cou ld n o t be r e s o l v e d .

74

W NI > I %rJ R : U\ ; 0 1

I - 1 -

I / c;! N: N I I I

%rj L

L t -

0 0' ' yi :

0- , ! L \ ;

O 131 01 0 s: ? I 0 : - , ; 31

; 0: - 3 " :

9 g; 0 3 , 3 : si - i , :,I

' - I

, 7 , m -, , - : - : 0: : -: 0: ; m .

zt' I N : 2 i N ;

P -

a

Y)

n u - -- -

'ON 2'03 - . I w h % u

LA

\4 rO .m t- .a YI

I,

-a P- t

w 0.

obtained, desp i t e a repea ted r e q u e s t .

,

0

4

4 4

C H A R A C T E R I S T I C V A L U E S O F T H E B U I L D I N G C O M P O N E N T C O M P U T A T I O N A L V E R I F I C A T I O N S

Building

Component

I 2

gdc,

Load

M a x . Lood

lkp/cm*)

18

D A M A G E R E P O R T

Slat;cal System

3

-

Comer

17

Ameaj .

A t time of occurrence of Damage T>'pe N 4 (Sect. 18i) the following are estimated:

f m m t

(meas.

I C ~ J

15

D,,,~,

16

- Dimensions

1, k d b. h, mar

3

l l @ J

23

mar

l /g

OO'/cml

22

L / f

21

N o

19

mtn L,

9

LI ImJ

4

m a

ton tc

I I @ J

24

fSch

I C ~ )

20

i?,,

Steel

'hp/cm>

10

& lvnl

m / n L i

Iml

A

( m m l

15

Reinforcing

l c * ) ; ~ 1 % ) ; IcM) ; p/py X-Direction y-Directinn

b

Icm)

5 6 7 8

Center hI fcml

Supports Center

I 1 I2

Supports

11 14

C H A R A C T E R I S T I C V A L U E S O F T H E B U I L D I N G C O M P O N E N T D A M A G E R E P O R T C O M P U T A T I O N A L V E R l F l C A T I O N S Dimensions Reinforcing 6dcr A t time of occurrence o iDvr iage Type N a

L, k d b, h, n. fi r c ~ ) ; p r % 1 ; 6 n w ; p&y AmeOL Permonen, (Secr. 18i) the fol lowing ore estimated: 2 Building

S Statical System &Direct ion y-Di rec t ion l r n m l , D~~~~~ Load

mi" L, Causer Q Component rnln Li 4 b Steel Center Supports Center / Supports Noifsch i L / f l 7;; tYwl 4

h, fmeas.

1

M a x . Load

'kpkm7 lcml (kp/cm21 l c r n l , d~O' /crn~ 1 1 0 9 I l b l ( m m l

3 1 4 5 6 7 8 9 1 0 11 12 13 I lr 15 : 16 1 17 18 P) 1 20 I 21 22 a 24 25 I I I I I l l

;Ipprox:::?.ltci . 3. . c:i: i\.idc. E;!de.:rl.: the s p r c i i ~ e d c u n c i - e r e stre!-.gth bad r,,it I ~ e e r

n r t i l~ned b e r . .;,. r l i f r o - t .<,tion. In the s t? . t lcx l i z ! ~ ~ ~ l ~ t ~ o i l t he 11 . i t e l -wa l l s \ r e r e n i , i -

i a n s ~ d e r e d , . T..c . s v r r of ti,r atcci ~ - c i ; l i ~ r c i n g was 7 . 0 crn t oo l a y e .

00 0\

21. SKETCHES AND DRAWINGS FOR THE VARIOUS CASES O F

DAMAGE.

The c i r c l e d n u m e r a l s in the following f i g u r e s give t h e r e spec t i ve d a m a g e

C a s e No. F u r t h e r de t a i l s c an t h e r e f o r e be obtained f r o m the fo rego ing

Tab l e s .

Types .of P a r t i t i o n W a l l s I Ausblldung der Ouerschofen:

n!erzuq . L. - . x S ! ! b - t . Reinforced Concrete Tie Beam

Durchbiegeschaden Nr. 30 Damage Case No. 30 /'

t- -4,35 -T-----780- -7

C r o s s Section 1C

Q u e r s c h n i t t

3rd Storey ->

Reinforced Concrete Waffl

Ceiling Slab 780 -435

Solid Concrete Ceiling Slab

- - - " - - - . - " .- -

Du r c h b iegeschaden Nl: 38 Damage Case No. 38 '/

/ Trennwande im Obergeschon = 6 cm Bimsdielen

Partit ion Walls in Top Storey - 6 cm Pumice Boards

Schni t t 7-7 I t

Section

Par ted 1-2 c m f rom ceiling

, I- 2 cm von Decke geliist f l

Schni f t 2-2 Section d

Damage C a s e NO. 49-

Durchbiegeschaden Nr . 49

- - - - - d e s a m t l u n g e I = 3 8 , 0 7 m - . - .--A i'

Overal l Length R = 38.07m

Ground F loo r

~ r d g e s c h o n 9

r I I ./-

-/

I -- -- I

- -

-

I I I I

,

I _ ---- P- I /1

S t a h l b e t o n - R i p p e n d e c k e d o = 7 + 26 = 3 3 cm

Reinforced Concrete Ribbed Slab

Observed Damagey

A u f g e t r e t e n e r S c h a d e n

W all2 Wall? W a n d a W a n d b

1

0 w

I 2nd Storeyv

Rug Storage, 20 cm high 1. O b e r g e s c h o n

his ru ( 5 cm breit 7

up to 1 .5 c m wide

p a l l

W a n d c

I

z Q3-

I

I

1 0 7 1 0 6

25 5 , B O ; 4 , 30+3 ,60 - ;K5 ,42 - ic-.. - . . ,~~~~~-~=c*----. -.=-- + 7

I-'"40 -

I 1 0 3

I I I I I

1 0 8

1

I v

25 --7,eo

I v- 1 0 5 . I

I !:

a- --- - - S f b - Uberzug----

Reinforced concre te suspender b e a m

Damage Case No. 56

D u r c h b iegeschaden N r . 56

Ground Floor

E rdgeschon

I/ Ribbed Slab

I R i p p e n d e c k e

/f I I d = 8 + 2 2 = 3 0 c m

/ Z

I-

c 1 1% = 1028 -

C ~ O S S Sections: Q u e r s c h n i t t e :

Wall Wall

n y - Richtung Direction

0 - 4 hx=25,6cm

Observed Dama e in Par t i t ion Walls..of 2nd S tore A u f g e t r e t e n e r Sc / a d e n in den Trennwonden des 1.8~

Wall Wand a p2.5 -3 .0 m

Wand b !-- 2,o m

Wand c

I

I

/--

I f C

" L I

Damage Case No. 64 Durchbiegeschaden Nr. 64

C r o s s Section 6iZuerschni t t I-1

IN

Ground Floor

- - -2wischen wande i m Part i t ion Walls in

Statical System of Ground Flo

Ceiling Slab -44j

stat. System d e r EG-Decke

Rahmen R5 _I - - F r a m g

I. und 2. Obergeschoh 2nd and 3rd Storey 3

Par t i t ion Wall Par t i t ion wall Part i t ion Wall Zwischenwand a ~7 Zwischenwand b ~7 Zwischenwand c 3

3rd Store L;, 2 . 5 ~

(-7 1. OG 2nd Storey

Exter ior Wall "We s t Exter ior Wall "South" Exter ior Wall "East" Aullenwand ,, West " /3 AuRenwand , ,S i idU J) Aunenwand ,. 0 s l " 17

Longitudinal Section

Ground F l o o r

( A r t i f i c i a l S tone )

D a m a g e C a s e No. 73

Wall

Wand Wall

Wand 2

W a l l Wand 3

W all

Wand 4- -

W a l l ,Wand 6

Longitudinal W a l l

4 Lungs wand

-- I I

3 II /i , I I

W a l l

Wand 5

Crack Pa t t e rns and Measured Deflections 5

RiBbilder und gernessene Durchbiegungen.

Querwande i m 3 . Obergeschol3, von de r Hal le aus gesehen. C r o s s Walls in 4th Storey a s viewed f r o m the Hall-way

< Abfangetrdger A

>

B r e a s t Summer

'I:, I f = 20 mm M l t t l e r e Hallenlgngswand i m 2. ObergeschoB.

4

@ h II

II li

a ~ b fang trager h 11 B r e a s t summer I

I/ I'

Middle Wall along Hall -way in the 3rd 'S torey , .

I f = 15 rnrn

M i t t l e r e Hallenlgngswand i r n 3 . ObergeschoB.

Middle Wall along Hall-way in the 4th s t o r e y /

i-;

L

, B r e a s t Summer ~ b l a h g e t r a ~ e r / ~

2nd Storey- 1. OG

LP

I II

II

I/ II ti II

A I1

f f - 3 r n m

M i t t l e r e Hallenlangswand i m 1. ObergeschoB.

Middle Wall along Hall-way i n 2nd Storey /"

I II !\ Y q

Staff & Emergency Staircase 1 4

Damage Case No. 106 Emergency Staircase 3 A

Sc haden Nr . lo6

Damage Case No. 128

Durchbiegeschaden Nr . 128

Dimensions Hafie in em

Cantilever slab

7 5 0

Torsion Beam

\ Fundomentbolken 50/85

Foundation gi rders

Deflection f lro Durchbregung In ern

r S u zenver iegung u n l - verd rehung ( e m ) 5 / c!;!-~ Rexure an rotatlon

West side Rotation 4 .

3 - - \ f Durchbiequng Ueflectlon

2 -

I I I zeit Time

1 0 1 1 1 2 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 2 3

22. PHOTOGRAPHS

Schaden Nr. 30

Damage Case No. 30

D a m a g e C a s e N o . 30

Schaden Nr. 30

Damage C a s e No. 30

Sohaden Nr. 30

Damage Case No. 35

Schaden Nr. 35

Damage C a s e No. 4 3

Schaden Nr . 43

Damage C a s e No. 65

Schaden Nr. 65

Damage Case No. 81

Schaden Nr . 81