An Experimental/analytical Study of the Dynamic Response of Staggered Structural Wall Systems

Abstract

The Imperial County Services Building of El Centro, California sustained severe damage during the 15 October 1979 Imperial Valley earthquake. Response of the structure during the earthquake was recorded by 13 strong-motion accelerographs. Vertical-load-carrying and lateral-force-resisting systems are described, and corrected acceleration records, calculated base shear and moment waveforms, response spectra, and Fourier amplitude spectra are presented.

A conceptual model of the N-S lateral-force-resisting system at the east end of the structure was formed. A small-scale reinforced-concrete structure was designed to represent the conceptual model. The small-scale structure was constructed then subjected to simulated earthquake motions to investigate the nonlinear dynamic response of such a lateral-force-resisting system.

Response of the small-scale test structure is interpreted through measured acceleration and displacement response, shear and moment response, Fourier amplitude spectra, and response spectra. Response is studied further using a nonlinear two-degree-of-freedom numerical model.

Using information developed from the experimental study, the recorded data from the Imperial County Services Building is evaluated. Failure of east-end first-story columns is investigated (1) by considering forces to act on the structure in only the N-S or E-W direction, and (2) by estimating axial load-moment combinations resulting from N-S and E-W forces acting simultaneously on the structure.