STRENGTH AND DEFORMATION BERA VIOUR OF PRECAST BEAM-COLUMN CONNECTIONS FOR REINFORCED CONCRETE BUILDING FRAMES

University of Wollongong Thesis Collection University of Wollongong Thesis Collections
1993
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Recommended Citation Bao-Zhong, Yao, Strength and deformation behaviour of precast beam-column connections for reinforced concrete building frames, Master of Engineering (Hons.) thesis, Department of Civil and Mining Engineering, University of Wollongong, 1993. http://ro.uow.edu.au/theses/2435
FOR REINFORCED CONCRETE BUILDING FRAMES
A thesis submitted in fulfilment of the requirements for the award of the degree
MASTER OF ENGINEERING (HONOURS)
February, 1993
11
DECLARATION
I hereby declare that this work has not been submitted for a higher degree to any
other University or Institute.
111
ACKNOWLEDGEMENTS
The author is grateful to Associate Professor Y.C.Loo, her supervisor, for his
guidance, encouragement, and invaluable advice throughout the period of this study.
Professor R. N. Singh, the Head of the Department of Civil and Mining Engineering at
the University of Wollongong is remembered for his encouragement and support. Thanks
are due to Dr. Joe Shonhardt and Mr. Sanaul Chowdhury who have given very helpful
assistance in the preparation of this thesis.
Finally, the author acknowledges the assistance received from Senior Technical Officer
Mr. R. Webb and other technical staff members of Civil Engineering Laboratories at the
University of Wollongong.
IV
ABSTRACT
Connection design is one of the most important considerations for the successful
construction of precast concrete strnctures. The configuration details of the connection affect
the strength, stability, ductility as well as load redistlibution of the structure under load.
This thesis presents a study of strength and deformation behaviour of beam-column
connections in precast reinforced concrete building frames. Six half-scale frame specimens
were designed, built and tested in the structural laboratory to evaluate the properties of
precast concrete frames. These included two pairs of precast frame specimens with two
different types of connections and two monolithic frame specimens. The sizes, reinforcing
bars, and configuration details were kept constant for all of these specimens to allow the
comparison of connection behaviour. The designs of the specimens were based on the
strnctural analysis of a five-storey concrete building frame, typical of a residential building.
The service loads, calculations for reinforcing bars, their configuration and manufacturing
were all based on the cuffent Australian Standard recommendations.
Experiments were designed and conducted to study the deformation behaviour and
strength of beam-column connections in precast concrete building frames. The tests were
undertaken in groups having the same concrete strength. The load-deformation curves of
connecting beams, load-strain curves of bars in tension and ductility and rotation of the end
beam when failure occurs were compared between the precast specimens and the
corresponding monolithic ones. This allows a comparison to be made of the connections
tested. The half-scale model tests reflected both the strength and def01mation behaviour of
prototype connections. They demonstrated satisfactory moment resistance and shear
capacities of the connections. The test results confirm that these connections would give
v
satisfactory load capacity and ductility perfo1mance and they can be safely applied to precast
reinforced concrete building frame construction.
The ease of construction, ductility and crack behaviour for the two connection types
studied are also compared and conclusions made based on the test results. Recommendations
for further work are also given.
VI
CONTENTS
Pages
2. LITERATURE REVIEW 6
2.1 Hist01ical Development 6
2.3 Expe1iments on Beam-Column Connections 13
2.4 Present Study 18
3.1 Structural Design 20
v 11
3.1.3 Half-scale model design 27
3.1.4 Computer analysis of the half-scale model 37
3.1.5 Results 37
3.2.1 General remarks 44
3.3.1 General remarks 51
" 3.4 Prefabrication and Construction of Specimens 61
3.4.1 Formwork and reinforcement work 61
3.4.2 Concrete specimens preparation 66
3.4.3 Assembly of the prefabricated frame specimens 69
3.5 Advantages and Disadvantages of the Two Connection Types 72
3.5.1 Connection Type 1 72
3.5.2 Connection Type 2 73
3.5.3 Comparisons 74
4.1 General Remarks 75
4.3 Experimental Procedure 80
RESULTS 84
5.3.3 Crack behaviour and failure modes of connections 98
6. CONCLUSION
6.1 Conclusion
REFERENCES
APPENDIX 1 Input and output data of computer analysis of the
frame (half-scale, Load Case 1)
APPENDIX 2 Input and output data of computer analysis of the
frame (half-scale, Load Case 2)
APPENDIX 3 Tables Representing Test Data
APPENDIX 4 Figures Based on the Test Results
110
110
111
114
118
127
137
162
IX
Concrete Residential Building Frame 3
2.1 Precast Reinforced Concrete Beams for the Casino at Biarritz (1891) 6
2.2 Knife Connection 13
2.4 Moment Connections 16
3.1 Principle Conception of Five-Storey Precast Concrete Building Frames 21
3.2 Basic Types of Components of Five-Storey Precast Concrete Building
Frames 21
3.4 I-I Section 24
3.7 Typical Floor Plan of Half-Scale Frame Structure 28
3.8 Structural Layout of Frames 28
3.9 Diagram of Concentrated Loads for Standard Frame 32
3.10 Analytical Model for Load Case 1 36
3.11 Analytical Model for Load Case 2 36
3.12 The Results of Computer Analysis (Half-Scale, Load Case 1) 38
3.13 The Results of Computer Analysis (Half-Scale, Load Case 2) 39
3.14 Bending Moment Diagram for Load Case 1 40
3.15 Sheming and Axial Force Diagram for Load Case 1 41
3.16 Bending Moment Diagram for Load Case 2 42
x
3.17 Sheaiing and Axial Force Diagram for Load Case 2 43
3.18 Structural System for the Precast Five-Storey Residential Building Frame 46
3.19 Connection Type 1 48
3.20 Connection Type 2 50
3.21 Intemal Forces at Typical Joint 53
2.22 Analytical Model for the Beam 11 53
2.23 Analytical Model for the Beam 13 53
3.24 Analytical Model for the Specimens 54
3.25 Reduction of Negative Moment 54
3.26 Reduction of Sheaiing Force 55
3.27 Reinforcement for Connecting Beams 56
3.28 Calculation Length of Columns 56
3.29 Reinforcement for the Column 57
3.30 Detail Drawing of Monolithic Specimens Ml,M2 58
3.31 Detail Drawing of Precast Specimens Pl, P2 (Connection Type 1) 59
3.32 Detail Drawing of Precast Specimens P3, P4 (Connection Type 2) 60
3.33 Test Results of the Tension Steel Bars (Y 12) 62
3.34 The Layout of Strain Gauges 64
4.1 Test Set-Up 76
4.2 Discs Layout for Specimens M, Pl, P2 79
4.3 Discs Layout for Specimens M2, P3, P4 79
5.1 Load-Deformation Curve for Ml, M2, Pl, P2, P3, P4 92
5.2 Crack Pattern for P4 99
5.4 Crack Pattern for M2 102
5.6 Crack Pattern for Ml 106
XI
5.7 Crack Pattern for Pl 107
5.8 Crack Patterns for P4, P2, M2, P3, Ml, Pl 108
A4.1 Load-Strain Curve for P4 163
A4.3 Load-Strain Curve for M2 165
A4.5 Load-Strain Curve for Ml 167
A4.6 Load-Strain Curve for P 1 168
A4.7 Load-Deformation Curve for P4 169
A4.8 Load-Deformation Curve for P2 170
A4.9 Load-Defon11ation Curve for M2 171
A4.10 Load-Defon11ation Curve for P3 172
A4.ll Load-Defon11ation Curve for Ml 173
A4.12 Load-Deformation Curve for P 1 174
Pages
3 .1 A Pair of Form work Bones and Reinforcing Cages 61
3.2 Assembly of the Column and Connecting Beam for Connection Type 1 70
3.3 Precast Frame with Connection Type 2, before Assembling 71
3.4 Precast Frame with Connection Type 2, after Assembling 72
4 .1 Test Set-Up 78
4.2 3054A Automatic Data Acquisition/Control System 79
5 .1 Crack Pattern for P4 99
5.3 Crack Patlern for M2 102
5 .4 Crack Pattern for P3 104
5.5 Crack Pattern for Ml 106
5. 6 Crack Pattern for P 1 107
•
Test Data of Tension Steel Bars (1)
Test Data of Tension Steel Bars (2)
The Strength and Slump of Commercial Concrete
The Components and Strengths of Dry-Packing Concrete
Load Stage Design for Specimens P4, P2, M2, P3, Ml, Pl
Details of Specimens
Test Results of the Specimens
01iginal Test Data of Deflections and Concrete Strains for Specimen P4
01iginal Test Data of Steel Strains for Specimen P4
A3.3 Load-Deformation Test Data for P4
A3.4 Load-Strain Test Data for P4
Pages
63
63
67
68
81
83
97
138
139
140
141
A3.5 Original Test Data of Deflections and Concrete Strains for Specimen P2 142
A3.6 01iginal Test Data of Steel Strains for Specimen P2 143
A3.7 01iginal Test Data of Deflections and Concrete Strains for Specimen M2 144
A3.8 Otiginal Test Data of Steel Strains for Specimen M2 145
A3.9 01iginal Test Data of Deflections and Concrete Strains for Specimen P3 146
A3.10 01iginal Test Data of Steel Strains for Specimen P3 147
A3.11 Load-Defmmation Test Data for P2 148
A3.12 Load-Strain Test Data for P2 149
A3.13 Load-Deformation Test Data for M2 150
A3.14 Load-StrainTestDataforM2 151
XIV
A3. l 7 01iginal Test Data of Deflections and Concrete Strains for Specimen Ml 154
A3.18 01iginal Test Data of Steel Strains for Specimen Ml 155
A3.19 01iginal Test Data of Deflections and Concrete Strains for Specimen Pl 156
A3.20 Oiiginal Test Data of Steel Strains for Specimen Pl 157
A3.21 Load-Defonnation Test Data for Ml 158
A3.22 Load-Strain Test Data for Ml 159
A3.23 Load-Deflection Test Data for Pl 160
A3.24 Load-Strain Test Data for Pl 161
xv
NOTATION
Ast = cross section area of tension steel
b = width of a section
D overall depth of a section
d = effective depth of a section
Es = modulus of elasticity of steel
f sy = yield strength of steel
fr = characte1istic compressive strength of concrete
fc" = characteiistic compressive strength of dry-packing concrete
G = dead load per unit length or area
I = gross moment of inertial
kuB = neutral axis parameter for a section with balanced steel ratio
L = centre-to-centre distance between supports of a beam or slab
la computation length of the column
Le = clearance height of the storey
M* = design moment
Pc = vertical load on the column
Pt = tension steel ratio
Pmax =
Q =
V* =
Vu,max
w
x
~fy
fill
~u
£cu
e
live load per unit length or area
design shear force
= ultimate shear force
distance from the support to contra.tJexurl!l point of connecting beam
deflection at initial yield for tensioning steel bars
ultimate hoiizontal deflection of connecting beam
ultimate vertical dellection of connecting beam
ultimate strain of concrete in compression
ultimate beam end rotation of connecting beam
1 Chapter 1: Introduction
1.1 General Remarks
Precast or prefab1icated concrete is the vital component in an industrial construction
method by which mass-produced components are assembled into buildings with the aid of
cranes and other handling equipment. The work of building construction is carried out in
two stages: manufacture of components in a permanent factory or workshop or a temporary
casting yard; and erection on the construction site. Precast concrete has been widely used in
building design and construction, even in some seismic regions, strong wind areas and
high-rise buildings in recent decades. Since it is the best way to achieve indust1ialization in
the building industry, new developments are continually being made in precast concrete and
reinforcement.
Precast concrete building components have found significant applicationsin building
constrnction in Australia. Increasing use of the technique is attributable to the advantages
associated with prefabiication, such as short construction time, low sensitivity to frost and
other weather conditions, reduced manpower requirement on site and the possibility of large
spans through the use of pretensioning. After erection of components, they should require
no (or only very little) subsequent finishing. Compared with monolithically cast in-situ
concrete structures, precast concrete allows for relatively simple repeated handling, so that , labourers
unskilled and semi-skilled' · can produce high quality products, generally only with a
relatively small supervisory staff of foreman and specialists necessary. Furthe1more, in this
particular building system, the centre of importance for quality control is transfeITed from
the building site, with all its problems, to the designer's desk and the factory. Beside these
considerations, precast concrete can obviously save plenty of formwork and is therefore
more economical.
Although precast concrete has many advantages, some problems still exist. First of all,
the connection between members poses the greatest problem to the designer. Skill is
required to design and detail a joint that can be easily formed on site at the same time
providing the necessary strength and ductility. Secondly, there must be a restriction on the
sizes and weights of precast concrete components as they all need to be lifted and placed in
position by some means. The lifting capacity and range of cranes available can govern the
sizes and weights of the components. Thirdly, some additional reinforcement and fittings
may be required for the stresses associated with handling, transportation and erection.
Sometimes, if a large number of components is required or if they are larger in size,
problems can mise concerning storage, transportation and erection costs.
In recent years, more and more attention has been focussed on the connections of precast
concrete structures, particularly in view of several collapses under service conditions during
earthquakes which have occurred all over the world; The design and construction of
connections is one of the most important steps in the engineering design of precast concrete
structures. The purpose of a connection is to transfer load and to provide stability. The
selection of a connection detail for 1 a_ particular situation requires consideration of
production, erection, serviceability, durability and ease of construction. A good connection
combines practicality and economy with sound design and therefore requires an
understanding of several factors: strength, serviceability, ease of production and erection,
and economics.
1.2 Objectives and Scope
The beam-column connection investigated in the present work was chosen from a five
storey precast reinforced concrete residential building frame design (Fig. 1.1). The basic
concept in constructing a medium-iise residential building using precast concrete is based on
the fact that when the building is constructed using cast in-situ concrete in the traditional
way, there usually exists some severe problems. These include honeycombs and dogholes,
usually appearing in the surface of the structure after formwork is removed because the
quality of construction is difficult to control. The requirements of architectural aestl:l.etics after the removal of the f ormwork. -
dictates that t~~ fi!lishings and fitt2~-~s-must be, cione f\ These need materials, scaffoldings,
manpower and time. Also the upper structure can not be poured until the concrete of the
A. Typical joints a. Portal frame
b. Column of upper portal frame c. Connecting beam
d. Hollow core floor slab e. Wall panel
Fig. 1.1 The Beam-Column Connection from a Five-Storey Precast
Reinforced Concrete Residential Building Frame
lower structure is sufficiently strong. All these factors increase the time of construction and
hence the costs. When a building is constructed of precast concrete, these disadvantages can
be well compensated. However, the prefabricated structure is not perfect and still has some
special problems in the system, such as:
(a) the joints design and construction;
(b) tolerances dming the manufactming and erection;
(c) verticality and
(d) crane capacity and construction procedures.
These again lead to a number~ of questions associated With the:present investigations which
need to be answered. They are:
(a) How to design the moment-resisting connections for a typical precast five-storey
residential building frame to allow safe transfer of load and have enough strength,
ductility and serviceability.
(b) How to design the tests to evaluate the strength and defo1mation behaviour of precast
concrete frame connections compared with connections of monolithic cast in-situ
concrete frame .
(c) Will it be easy to manufacture these precast components and assemble them on site.
(d) What are the weak points of the connections dming construction and in service .
(e) What conclusion and recommendations can be reached after the tests of these
specimens.
Thus the main objective of the present study and associated expe1iments was to develop
satisfactory moment-resisting connections in the precast concrete building frames which can
address the above-mentioned problems. Two types of beam-column connections were
designed conforming to the guide lines given in PCI (1988), APCG (1990) and Potter
(1990). Six half-scale frame specimens were designed and manufactured, including two
monolithic frame specimens for the comparison. Tests on the half-scale specimens for the
beam-column connections were conducted to investigate the strength and deformation
behaviour, the crack patterns and failure modes of the connections. Test results confirmed
that the design and configurations for these beam-column connections are safe and practical.
They can develop the satisfactory strength and ductility and are easy to manufactur · and
construct1 • •• The weak points of these connections have also been identified. Conclusions
and suggestions for further studies in this respect have been made in later chapters.
1.3 Summary of Contents
A summary of the contents of the thesis is given below:
• A review of the literature on prccast concrete development, connection design,
construction and experiments in the precast reinforced concrete frame with particular
emphasis on the beam-column connections is presented in Chapter 2 .
• The design and construction of specimens for the connection tests are described m
Chapter 3 .
. The test set-up and expe1imental procedure(orconnection tests are desclibed in Chapter 4 .
• Test results are presented and discussed in Chapter 5 .
• The conclusions and recommendations for further study are given in Chapter 6.
The references are listed from page 114 to 117. The input and output data of the
computer frame analysis are reproduced in the Appendices 1 and 2, (pp. 118-136); the test
data for all of the specimens (Tables A3. l to A3.24) are given in the Appendix 3; all the
curves from the test results (Figs. A4. l to A4.12) are shown in the Appendix 4.
6 Chapter 2: Literature Review
CHAPTER2
2.1 Historical Development
Precast concrete is a product designed to meet the needs of modern industrial
development. Industrialization in building construction is a natural extension of the type
which has taken place in the other industiies. Development has been rather late, but rapid.
The use of precast concrete has been associated with reinforced concrete and prestressed
concrete from the very beginning of the industry. The first precast structural members were
probably the concrete beams for the Casino at Biarritz, which was built by the
contracting firm Ed. Coignte, Paris, in 1891 ((Fig. 2.1), Koncz, 1976 ). The beginning of
small precast concrete plants was due to the successful construction of prestressed concrete
bridges and their components in the early 20th century. The first large roofing slabs were
Fig. 2.1 Precast Reinforced Concrete Beams for the Casino at BiaITitz (1891)
after Koncz, 197 6
7 Chapter 2: Literature Review
probably those made in Brooklyn, U. S. A. in 1900. In 1905, a prefabricated floor structure
for a four-storey building was constructed in Reading, Pennsylvania, U.S.A. Only the
columns were cast in-situ. In 1906, lattice-type beams made their appearances in Europe
and were very successful. In the United States, after the success of the Walnut Lane Bridge
in 1949, several small precast concrete plants began experimenting and producing
pretensioned prestressed concrete components for building structures. These complised
hollow slabs, flat slabs, channel slabs, beams, single T's, double T's and piling. This was the
first time that industrialized production of structural components took place (Sheppard and
Phillips, 1989).
In Europe the prefabrication of residential buildings in concrete and reinforced concrete
commenced after the First World War. The most advanced experiments were made using
storey-height wall panels, installed by means of a crane, in Germany at Braunheimnear
Frankfurt-on-Main and at Munich. In Britain, too, a number of prefabricated construction
systems were developed around this time. Most of these embodied a structural framework.
(Koncz, 1976).
In the United States,…