nisee

National Information Service for Earthquake Engineering
University of California, Berkeley

 Importance of Construction Aspects
 Earthquake 
Engineering
 Contents
 Ground Failure
 Ground Shaking
 Solutions
 Foundation
 Superstructure
 Construction
 Research

ILLUSTRATION OF THE IMPORTANCE OF CONSTRUCTION ASPECTS

      The importance of construction aspects has been discussed in Importance of Construction and Maintenance and in Refs. 12 and 13.  Field inspection of the performance of structures during earthquakes has revealed that a large percentage of damage and failure has been due to poor quality control of structural materials and/or poor workmanship - problems which could have been corrected if the buildings had been carefully inspected during construction.  Examples of observed damage due to poor workmanship are illustrated in Slides J102-J109.

J102.  Holy Cross Building, Los Angeles, California, 1971 San Fernando Earthquake.  View of the east reinforced concrete shear wall of the 7-story tower of this building.  Note the failure of this wall that occurred at the fourth floor level during the earthquake due to poor workmanship. 

      For the main building column and shear walls a normal weight concrete was specified using natural aggregates with fc = 345 kilograms per square centimeter.  The concrete for the floor slab was specified to have fc = 210 kilograms per square centimeter and to be a lightweight concrete using expanded shale lightweight aggregates.  In the actual construction the lightweight concrete specified for the slab was also cast through the normal weight concrete of the shear wall, thus creating a discontinuity in the equality of concrete over the height of the shear wall.  The weaker layer of lightweight concrete was crushed by the harder and stronger normal weight concrete, inducing the failure shown in this slide.

J103.  Olive View Hospital, Medical Treatment and Care Unit, 1971 San Fernando Earthquake.  View of the end of one of the four wings of this 5-story reinforced concrete building after the earthquake (see also Slides J61-J64, J72-J73, and Refs. 6 and 23).

      Note the large distortion of the first soft story columns (one of the corner columns underwent 0.81 meters of lateral displacement in a clear height of about 4.27 meters, resulting in an interstory drift index of 0.19) and the complete disruption of the concrete in the poorly tied (confined) corner column, while the concrete in the spirally reinforced concrete core of the other columns remained intact for most of the height.  However, as illustrated in the close-up of Slide J104 and particularly J105, as a consequence of poor workmanship and poor (or complete lack of) inspection, the lateral resistance capacity and particularly the energy dissipation capacity of a large percentage of these spirally reinforced concrete columns was greatly reduced due to a premature ending of the spiral reinforcement at the top of the columns.  The spiral was ended before reaching the spandrel girder, leaving this critical region of the column (the top and here the plastic hinge formed) without any lateral confinement and therefore greatly reducing its energy dissipation capacity.

J104.  Overall view of one of the first story columns of the structure in Slide J103.  Note the interruption (ending) of the spiral reinforcement before being anchored in the girder and therefore the lack of confinement of the concrete at this critical region of the column.

J105.  Close-up of the top of the column shown in Slide J104 illustrating clearly how the concrete in this critical region has been disrupted (broken off) as a consequence of the premature (early) ending of the spiral reinforcement.  Good inspection of the reinforcement before placing the formwork and the casts of the concrete should have detected this poor workmanship.  Note the excellent state of the confined concrete in the rest of the column.

J106.  J. C. Penny Building, Anchorage, Alaska, 1964 Alaska Earthquake.  View of damage to the south and east walls of this 5-story reinforced concrete building induced by ground shaking.  The building had to be demolished after the earthquake because of catastrophic failures of many of the structural elements and of serious damage to the non-structural components. 

      The structural system (used in Slide J106) consisted of thick (0.25 meters) reinforced concrete flat plates used as the floor system, supported on reinforced concrete columns and shear walls.  The building was almost square in plan, but the arrangement of the effective shear resisting walls was asymmetrical [in the upper stories they were located chiefly in the south and west faces (walls); and in the bottom three stories shear walls were also added in the two south bays of the east facade as illustrate in this slide].  As a consequence of the large eccentricities between the center of mass and center of rigidity (which was accentuated by the use of very heavy precast concrete non-structural panels on the north and east walls), large torsional forces and deformations were induced during the earthquake.  These torsional forces and deformations (which can be seen in this slide) caused the failure of the shear walls at floor level due to poor detailing and workmanship of the anchorage for the non-structural precast panels.  Note the weakness introduced in the shear walls at the second and third floor levels of the east facade, and how this weakness led to the failure and significant shift of the second story wall with respect to the first story.  Although some of the panels were still attached to the building after the earthquake, as can be seen in this slide, most of them broke loose from the building and fell into the sidewalk and street, killing two people and destroying several cars [7].

J107.  J. C. Penny Building, Anchorage, Alaska, 1964 Alaska Earthquake.  View of the northeast corner of the building after the earthquake. 

      The dramatic collapse of the upper four stories of the building in Slide J107 was a consequence of poor selection of the structural layout (large eccentricity), the use of unnecessary masses (heavy precast panels at the east and north facades), and poor detailing and particularly poor workmanship in the anchoring of the precast elements to the structural system.

J108.  Close-up of the bottom of the first story of one of the columns of the Cite Al Naser Market Building, El Asnam, Algeria, 1980 El Asnam Earthquake. 

Considerable honeycombing was observed with complete lack of mortar in many of the columns of the buildings in Slide J108.  It was possible to break away large parts of concrete with just a screwdriver or a kick with a boot as was the case illustrated in this slide.  Adequate attention was not given to concrete mixing, placement, consolidation, and/or curing and in the placement of the steel reinforcement.  This poor quality control of materials and poor workmanship contributed significantly to the catastrophic collapse of these buildings [4].

Balanced Stiffness, Strength and Ductility Click here for Table of Contents Research and Development Needs

The University of California, Berkeley
Copyright 1997, The Regents of the University of California.
Structural Engineering Slide Library, W. G. Godden, Editor
Set J: Earthquake Engineering, V. V. Bertero

Site Design: Vivian Isaradharm,  Oct. 97.
Mail to:  eerclibrary@berkeley.edu