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REINFORCED CONCRETE STRUCTURESFAILURES
CAUSES AND RESPONSABILITIES
Carlos Videla C.ESCUELA DE INGENIERÍA
PONTIFICIA UNIVERSIDAD CATÓLICA DE CHILE
Carlos Videla © 2010
CONTENTS
Lights & ShadowsTechnical Causes
The Human FactorResponsibilities for Construction Faults
Conclusions
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Carlos Videla © 2010
REINFORCED CONCRETE: LIGHTS & SHADOWS
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R.C. Lights
Panteón de Agripa, Roma, 120 DC / Arq. Apolodoro de Damasco
Federico Assler,Premio Nacional de Arte 2009
Marriot,145 m1999
Metro Línea 4,2004
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Challengues of R.C. ConstructionCostanera Center
Height: 300 metrosStories: 60
fc’ = 70 MPa20xx -??
Titanium La PortadaHeight: 192 metros Stories: 52
fc’ = 60 MPa2007-2010
Marriot,145 m, 1999
Tall Buildings
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160 pisos 705 m.
Height: Kingdom Tower, Arabia Saudita
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Carlos Videla © 2010
Shapes: Spiral Tower – Songdo, Korea
175 m, 52 stories, giro 110°7
David Scott, ARUP Carlos Videla © 2010
New Technologies
SCC
Concrete Pumping Test over 600 m, Dubai (Feb. 2005)
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Dificulties of DesignRonald Klemencic, Magnusson Klemencic Associates
Wind TunnelCostanera Center
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SHADOWS OF CONCRETE
CONSTRUCTION
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The dark side of the force
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Pittsburg garage parking
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Even the collapse of the building can be produced
Alto Río Building 27 de Marzo de 2010Concepción, CHILE
The document detected three types of deficiencies in the structure: bonding in the horizontal concrete construction joints,...…
Carlos Videla © 2010Carlos Videla © 2010 14
Collapse of the works even without loads
13 stories building under construction tilt in Shangai 29 of June, 2009http://cache.daqi.com/view/2617990.html
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Degradación del hormigón producto de la corrosión de las armaduras de la losa
and Reduce the Service Life of the Structures
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TECHNICALCAUSES
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February 27th, 2010 – ChileCHILEAN EQ. CASE
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DisclaimerThis presentation uses a large number of pictures andevidence that professor Videla has gathered as anevidence of the Earthquake and Tsunami in Chile.
Most photographs where taken personally or by members of his company however, others have been obtained from internet and other sources and makes it very difficult to independently acknowledge some of the sources.
However special thanks are given to:• Augusto Holmberg, CEO, ICH• René Lagos, renelagos engineers• Rodrigo Mujica, VMB Ingeniería Estructural• Carl Luders, SIRVE S.A.• Patricio Bonelli, Universidad Santa María • Leonardo Massone, University of Chile• René Guerra y Daniel Díaz, Videla y Asociados
Carlos Videla © 2010
SOME FIGURES ABOUT THE 27FCHILEAN EARTHQUAKE
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Some Figures about the 27F EQ• Chile 2010 EQ Mw = 8.8• Epicenter close to Concepción• Depth: 35 Km• Subduction zone - Length of
rupture 500km (approx.)• RC building damage• Affected cities - Concepción, Viña
del Mar, Santiago, among others
Maipú, Renadic – 10/05 reportCarlos Videla © 2010
Accelerations …
Informe preliminar Nº 3 - 15 de Marzo de 2010Red Nacional de AcelerógrafosBoroschek R, P. Soto, R. Leon,, D. Comte www.renadic.cl
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THE GOOD AND THE BADOF THE 27F EARTHQUAKE
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The Very Bad Earthquake Effects...
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• Dead or missed people: less than 500 (mainly by tsunami)
• Houses damaged: 300,000 to 500,000 (mainly adobe)
• Reconstruction: 30 US billions (15% GDP)ICH Non oficial figures
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• Maremoto = Tsunami
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• Water run-up
Courtesy Univesidad CatolicaRecognition group
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Historical Buildings
Museo Nacional de Bellas Artes
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• Curico Church
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Adobe Construction
Typical Chilean Farm House
Adobe construction
Adobe construction Adobe construction
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• “Modern” adobe construction
V&A
Carlos Videla © 2010
How did buildings performed?Considering only buildings between 1985 to 2009 (CChC)
• Buildings that collapsed: 4
• Buildings to be demolished: 25 - 50 (estimate)
• Buildings heavily damaged: 50 – 100 (< 1% stock of bulidings)
• Non structural components: extensive damage
• Number of buildings 3 + story 9.974
• Number of buildings 9 + story 1.939
• Failures 3 + story buildings: 0.5%
• Failures 9 + story buildings: 2.8%34
RC Buildings - Good & Bad
Carlos Videla © 2010
EXAMPLES OF BUILDINGS WITHOUT STRUCTURAL DAMAGE
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52 storIes192 meters high
Titanium Tower – Santiago, Chile
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Titanium Tower
Energy dissipation devises
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Telefónica Building – Santiago, Chile
• Construction Area: 65.000 m2 total35.000 m2 main tower
• Tower typical floor: 20m. x 47m.• Building height 140 meters• Stories 33 + 3• Year of Completion: 1996
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Isidora 3000 – Chile (2008)Mix use
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Isidora 3000
2nd floor
3rd floor
Structure Singularities:
Column Deviations
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Justice BuidingSantiago Chile. (2003)
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Office buildings (2008)Isidora Foster + Magdalena – Chile
• 25 stories
• 9 basement
• 72.000 m2
Carlos Videla © 2010
EXAMPLES OF BUILDING FAILURES
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Concepción
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Edificio Salas 1343 Torre A - Concepción Edificio San Pedro Concepción
Edificio Centro Mayor - Concepción Edificio Obispo Salas - Concepción
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Edificio Alto Río Edificio Alto Río
Edificio Alto Río - Concepción Concepción
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Edificio O´Higgins 241 Viña del Mar
Edificio Toledo – Viña del Mar Edificio Tricahue – Viña del Mar
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Edificio Tenerife – Viña del Mar Santiago
Emerald - Santiago Condominio los Robles - Huechuraba
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Central Park - Santiago Edificio DonTristán - Maipu
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Design Failures
Flexural-compression brittle failures Concrete crushing and rebar buckling Overall buckling of thin walls Splice failure Soft floor (irregularities) Lack of concrete confinement Deficient reinforcement detailing Few shear failures Walls too slender (thickness 20 cm) Very heavy loaded walls
Carlos Videla © 2010
Walls• T & rectangular walls with
flexural-compression damage at 1st floor or basement
• T walls with damage at web• No SBE – concrete crushing and
rebar buckling• Splice failure
P. Bonelli
Rebar Fracture
Splicefailure
J. Wallace
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Walls• No SBE – concrete crushing
and rebar buckling & fracture• Overall buckling – thin walls
J. Wallace
J. Wallace
Diagrama de Piso Blando
Carlos Videla © 2010
Muro discontinuo de zócalo (Edificio Hipódromo Chile)
Soft floor
Armaduras abiertas en muro discontinuo (Edificio Sol Oriente)
Carlos Videla © 2010
Lack of concrete confinement
Diagrama Armadura TransversalCarlos Videla © 2010 68
Compression failure and buckling of vertical bars
Edificio El Parque
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Detailing of reinforcement
Reinforcement bent at 90°(Edificio Emerald)
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Detailing of reinforcement
Falta de retorno de la malla horizontal (Edificio El Parque)
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Detailing of reinforcement - splice
Anclaje vertical de armaduras horizontales (Edificio El Parque)
Edificio Los Cerezos
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Flexural-compression failure
Edificio Emerald
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Few shear failures
Edificio Central Park
Edificio El Parque (fisura corte 0,5 mm)
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Edificio Toledo, Viña
Edificio Alto Río, Concepción
Walls too slender (thickness 20 cm)
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Very heavy loaded walls
Edificio Central Park
Edificio El Parque
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Car Park
Torre Bilbao, Santiago
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The typical structural wall in a Chilean building need not have boundary elements or special transverse reinforcement.The good performance of the majority of these buildings during the March 3, 1985 earthquake suggests that bearing walls with limited detailing may be an effective construction form for earthquake resistance
• After the 1985 Chilean Earthquake it was thought:
Concrete Design Code• Limit slenderness of the shear walls• Limit the compression in shear walls• Confinement of boundary elements• Confinement at longitudinal splices
Earthquake Loading• Revise the design spectrum• Revise the soil amplification effects • Define displacements and rotational demands
After the 2010 Chilean Earthquake some things have to be revised:
Carlos Videla © 2010 79
Construction Failures
De most frequent encountered problems were:
• Reinforcement detailing (Missing confinement reinforcement)
• Bad construction joints • Lack of concrete continuity• Excess reinforcement cover, reducing
the lever arm• Movement joints• Low strength concrete
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Reinforcement detailing
• Confinement• Location• Righteousness• Cleaning• Stirrups• Ties• Splices
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Reinforcement detailing: confinement
• Horizontal mesh reinforcement not closed• Missing confinement reinforcement
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Reinforcement detailing
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Reinforcement detailing
I never thought that this could really happen.
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Reinforcement detailing: stirrups
If we where following ISO why we did not get
the right spacing.In this case at least they
should have place the steel.
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Reinforcement detailing: detailing
• Different to drawings
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Reinforcement detailing: location
Eccentric reinforced bars
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Reinforcement detailing: location
• No cover
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Bad construction joints
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Lack of concrete continuity
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Movement joints
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Excess reinforcement cover
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Low strength concrete (poor)
(furtive – covert)
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FAILURES OF NON STRUCTURAL MEMBERS
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Failure of Non Structural Members
• Partition walls
• Ceilings
• Glasses
• Equipment
• Feetings
• Finishing
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Partition walls
Gypsum
Tabiques de yeso(Edificio en Santiago, Ñuñoa)
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Ceilings
Pudahuel AirportThe Chilean International Airport was out of service at the most critical time for Chile.
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Glasses
3 m
Windows
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Glasses Glass Doors
Concepción Airport
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Equipment
Machine room and heaters equipment(Ciudad Empresarial Building, Santiago)
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Fittings
Daños en sistema de aire acondicionado y proteccióncontra el fuego (Santiago y Concepción)
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Furniture
Daños del contenido (Edificio Stgo., Ciudad Empresarial)Carlos Videla © 2010 102
• Veneer 90% OK
DUOC; San Carlos de Apoquindo
Finishing
V&A
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• StuccoFinishing
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Excessive thickness of stucco to rectify plumbs
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• Architectural Details Finishing
Universidad del Desarrollo
V&A
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• Curtain Walls
OK
Finishing
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Secondary Structures
Pudahuel Airport
Mall Portal La Dehesa
V&ACarlos Videla © 2010 108
Schools
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THE HUMAN FACTOR
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Causes of the Pathologies of RC Structures
Ignorance or Irresponsability?
Incapacityor Indifference?
Inexperienceor Negligence?
Incompetencyor lack of foresight?
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The human factor
CAUSES: Ignorance Carelessness Negligence Excess of confidence Apathy Lust
The Pareto variable of construction quality, whose improvement has the largest impact on the
improvement of the total, been equal the rest of the factors is
THE HUMAN FACTOR
García Messeguer A.
Carlos Videla © 2010
LET SEE THEKNOWLEDGE
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From an Ancient English Proverb
...... (Structural) Engineering is the art of moulding materials we do not wholly understand into shapes we cannot precisely analyse, so as to withstand forces we cannot assess, in such a way that the community has no reason to suspect our ignorance........
Ironbridge, Cast-iron arch bridge-1779,River Severn, Coalbrookdale, Shropshire, England
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Books
Carlos Videla © 2010 115
A. Neville (1981)
If the reader is unable to design a satisfactory mix he should seriouly consider the alternative of construction in steel
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IF WE KNOW SO MUCH,WHY THE FOLLOWING
FAILURES OCCUR?
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Postensioning of Flat Slabs(Quito, Octubre 2002)
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V&A
V&A
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Unshoring of slabs
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Slab camber and make perpendicular walls during construction
Slab Wall119
V&AV&A
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COULD BE THAT WE ARE NOT DOING AND APLYING SOUND ENGINEERING PRINCIPLES?
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Sophisticated modeling programs tools for structural design, but…
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Possible weakness: Uncertainty on structural modeling
renelagosengineers
• Modeling of foundations:– Vertical rigidity of the soil– Empotramiento at the base versus
foundation rotation– Lateral confinement of the
underground
• Modeling of structural elements:– Use of finite elements versus uniaxial elements– Rigid or flexible diaphragms – Geometrical properties with or without cracking– Etc.
Carlos Videla © 2010
Divorce between Structural Engineering and Construction Engineering
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Structural Engineers do not consider the construction process in the design stage
Magellines Pier, V&A 2012
Excessive cracking due to construction sequence
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Forensic Engineering (post construction structural evaluation)
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Magellines Pier, V&A 2012
Carlos Videla © 2010
Construction Engineers used to point out that structural engineers were standing far from the actual constructions sites. This still remains true but, …
G. Thenoux
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Massive R.C. Mat Foundations, Costanera Center Building, 2010SCC – 50 MPa
Divorce between Structural Engineers and Reality
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Designing something difficult to built (common sense)
Moving reinforcing bars with a bar to vibrate concrete
Sup. 25@10 + Suple 28@10 Inf. 25@10 + Suple 28@10
Sup. 16@20 + E 12@40
Inf. 18@
R.C. SlabV&A, 2008
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Divorce between Construction Engineering and Construction Management
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Since construction management arrived in our field we have been talking to different language.G. Thenoux
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Carlos Videla © 2010
Divorce between Construction Engineering and Construction ManagementSince construction management arrived in our field we have been talking to different language.
Carlos Videla © 2010
Many construction engineers are also looking the construction site through the computer screen. This is ok since they make take advantage of many new application tools for planning, programming and building however…..
Carlos Videla © 2010
Drawings are a window through which the knowledge
is seen (or measured)Carlos Videla © 2010 Carlos Videla © 2010 132
Some phrases about Constructors
• Drawings must be very detailed to avoid constructors to think o interpret (design office).
• Information for in situ engineers must be very concise and simple and a maximum of 2 pages extension because they don’t read.(visiting engineer of a construction company).
• Constructors don´t have the capacity nor the knowledge allowing them to place in doubt structural design drawings(owner of a construction company).
• In situ professionals don´t like to write to register anything (all the previous).
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More phrases
• Constructors are only worried about administrative duties like acquisitions, quotations, budgets, programming; they don´t care about the execution of the work in-situ and rely on the work of the technical labor(me).
• The main work of the ITO is adminsitration of the contract: approve payment, check productivity, evaluate time, etc.; they don´t verify the quality of the construction(structural engineers).
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Casting mas concrete
Construction Engineering = Rule of Thumb?
Mass Concrete Case
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HOW GOOD ARE WE DOING WITH QC/QA IN BUILDING
CONSTRUCTION?
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Carlos Videla © 2010
LUST
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Carlos Videla © 2011
Concrete- testing company says NYC resultswere not fakedAmerican Standard Testing and Consulting Laboratories denies allegations that it falsified thousands of test results on several New York City projects, including a La Guardia Airport control tower and the new Yankee Stadium. Company President Alan Fortich and five staff members Thursday pleaded not guilty to racketeering and other charges. The company's defense attorney, Richard Leff, said the concrete strength tests were done correctly.
•The New York Times•The Associated Press
Concrete SmartBrief [email protected] 5, 2011
The six defendants accused of falsifying concrete tests in State
Supreme Court on Thursday. By William K. Rashbaum
Published: August 4, 2011 Carlos Videla © 2010
RESPONSIBILITIESFOR CONSTRUCTION
DEFECTS
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ENASEI 2010 ‐ Institutode la Construcción
Article 18: The first vendor owner of a construction will be responsible for all the damages and financial losses due to faults or defects on it, whether…..
DEVELOPERS = RESPONSIBLE (Guilty)
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ENASEI 2010 ‐ Institutode la Construcción
HOW DEVELOPERS WERE SEEN
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SCIENTISTS
The Globe and MailOctober 23, 2012
L'Aquila EQ
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Construction Process and ResponsibilitiesSTAGE COMPETENCE RESULT
Structural Engineer
Construction Engineer
Resistencia prevista en
función de los Materiales y
Diseño Proceso Constructivo
In situ Supervisor
Structure Actual Quality
Design
Construction
FinishedProject
Fabrication
Selección de materiales más adecuados y económicos.
Fabricación Transporte
Colocación Armaduras Moldajes Hormigón
Compactación Curado
Labour
Labour
Structure Specified Quality
Structure PotentialQuality
QA&QC in-situ
Inspection
Architect
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HIDDEN CONSTRUCTION DEFECTS
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Would you buy this Lamborghini Murciélago?
And now?
¿ ?
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El Mercurio, 3 de Septiembre 2010
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It affects the public faith
HIDDEN CONSTRUCTION DEFECTS
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Ethic?“I put less cement on the foundations, but nobody will never notice”
What can we expect of these cases?
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Movement and distribution moulds
Movement
Horizontal moulds
Vertical moulds
ARCHITECTURAL
CONCRETE??
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Construction Joints
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El Alma Project,V&A, 2008
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Embedded pipes in reinforced concrete elements
Cover failure
Slab Wall
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CONCLUSIONS
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¡ Thanks !
Dr. Carlos VidelaOctober, 2012