Seismic Response of a 7-Story RC Building

Experience in earthquakes has shown that structural walls are an excellent lateral force resisting system but in high-seismic regions like California, buildings incorporating structural walls can be prohibitively expensive and difficult to build. Structural engineers in California have often questioned that the current design lateral forces for structural wall buildings renders this attractive lateral force resisting system largely uneconomical and that significant savings could be made if lateral forces could be reduced, particularly in the foundation and in the lower levels of the walls where heavy congestion is observed. This project consisted of a shake table test of a 7-story full-scale slice of a reinforced concrete residential building with cantilever structural walls acting as the lateral force resisting system. The objective of this research program was to verify the seismic response of reinforced concrete wall systems designed for lateral forces obtained from a displacement-based design methodology. These forces are significantly smaller than those obtained from force-based design methodologies in building codes in United States. It is interesting that new displacement-based design methodologies indicate that walls could be designed with significantly less amounts of longitudinal reinforcement and still perform satisfactorily by properly controlling interstory drift, and hence displacement sensitive non-structural damage, and by having sufficient lateral deformation capacity to meet the demands in a rare but strong earthquake. The full-scale structure was subjected to historical input ground motions recorded in Southern California that represent demands of earthquakes with approximately 50% and 10% probability of exceedance in 50 years. The project was funded by the Englekirk Board of Advisors, an industry group supporting research at the Charles Lee Powell Structural Laboratories at the University of California, San Diego.