DYNAMIC RESPONSE OF THE IMPERIAL COUNTY SERVICES BUILDING DURING THE 1979 IMPERIAL VALLEY EARTHQUAKE

This dissertation investigates the response of the Imperial County Services Building during the Imperial Valley earthquake of October 15, 1979. The response of this six-story reinforced concrete frame and shear wall building is of significance to earthquake engineering because it is the first response recorded in a building which suffered major structural damage due to strong ground motion.;The displacement response characteristics of the building are also investigated. The relative building displacements are computed as the difference between the absolute building displacements at various locations throughout the building. The relative displacements are used to illustrate the full-scale building response in elevation and plan views to show the translational and torsional responses and the in-plane bending deformations of the roof diaphragm.;The reliability of the building displacements computed, from the doubly integrated corrected accelerations, during routine processing of the strong motion data (Trifunac and Lee, 1973) is of concern since the lower frequency limit used to correct for baseline errors has not been deterministically assessed. The relative displacements are used to investigate the effects of the implementation of a higher value for the lower frequency cutoff value which is chosen to exclude all motions in the building with periods longer than the longest period of the building.;Because the building was extensively instrumented, a nonparametric analysis of the response using all records obtained in the building and at the nearby free field site is derived to study important response features during the earthquake. A time-varying spectrum is generated for each acceleration record which decomposes the acceleration into a function of time and frequency. This enables the translational and torsional responses and the influence of pile-foundation-structure interaction to be studied. The first two translational modes in the frame and shear wall directions and the first two torsional modes were excited. Pile-foundation-structure interaction was evident in the time-varying base spectra in both directions.