Citation

Cassano RC. Transp. Res. Rec. 1976; 579: 27-35.

Copyright

(Copyright © 1976, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

After the earthquake at San Fernando on February 9, 1971, significant changes were made in structural details of bridges designed by the Division of Structures, California Department of Transportation. New Seismic design criteria were developed that consider both fault proximity and local soil conditions. Response coefficient curves, which are a key element of these new criteria, were developed by determining average elastic response spectra for rock motion and then modifying these spectra to reflect the influence of soil conditions. Considerable engineering judgment was used in assessing ductility and acceptable risk so that the elastic curves could be scaled down to a desirable level for design. Response coefficient curves can be used to find suitable equivalent static force coefficients or as design spectra for use in a dynamic analysis of a response spectrum. The simplified design method is adequate for small structures, but a dynamic analysis is required to accurately predict the response of long, curved structures with intermediate hinges and widely varying column lengths.