Menu
Contact Us Search
Organization Title

Verification of Response Spectral Shapes and Anchor Points for Different Site Categories for Building Design Codes

by W. Silva and G. Toro

Silva, W., and G. Toro (1996). Verification of Response Spectral Shapes and Anchor Points for Different Site Categories for Building Design Codes. SMIP96 Seminar on Seismological and Engineering Implications of Recent Strong-Motion Data, p. 37 - 52.

Click on the link below for the full text:

PDF (Adobe PDF (SIZE 535 KB)) - Requires Adobe Acrobat Reader or other PDF viewer.


Abstract

The dramatic increase in strong ground motion recordings over the last several years has provided both the impetus and opportunity to empirically examine the seismic design criteria in both the UBC and NEHRP code provisions. In this project both spectral design shapes and the usefulness of two spectral anchors are investigated using a comprehensive strong motion database and updated empirical attenuation relations. For the shapes, the results suggest that both the UBC and NERHRP design spectra provide enveloping criteria (except for site D at short periods) including cases for sites within 10 km of the fault rupture surface. For the NEHRP design spectra, comparison of the Fa and Fv factors to those implied by a recently developed empirical attenuation relation suggest that the NEHRP Fa factors may reflect too little nonlinearity while the Fv factors may show too much nonlinearity. Comparisons of the code shapes to the results from probabilistic seismic hazard analyses indicate that the fixed UBC shape has a moderate tendency to under-predict amplitudes for T > 1 sec in places like San Francisco and Sacramento where large (M > 7) earthquakes dominate the hazard at these periods. The more flexible NEHRP shape avoids this problem, but requires the specification of two anchoring points.