Citation

Privitzer E, Robinson RR, Cooper JD. Transp. Res. Rec. 1976; 579: 7-15.

Copyright

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

DOI

unavailable

PMID

unavailable

Abstract

A conclusion of the studies of the earthquakes in Alaska in 1964 and San Fernando in 1971 was that to design a bridge to entirely resist the effects of strong-motion seismic loading is both impractical and uneconomical. Interest in retrofitting existing highway bridges to minimize such damage increased dramatically after the San Fernando earthquake, which caused extensive damage to the California freeway system, including bridges under construction and those newly completed. Cost-effective retrofit measures can be practically and economically implemented and have the effect of minimizing damage resulting from strong-motion seismic loading rather than eliminating it entirely. This paper describes various types of retrofit measures and discusses a numerical seismic method of analyzing their effectiveness. A bridge in northern California, a region of high seismic activity, is described and analyzed. The bridge is mathematically modeled as a three-dimensional space frame and is subjected to a hypothetical earthquake in the form of ground surface displacement time histories based on a statistical evaluation of the seismicity of the site. The bridge is first analyzed as built to determine whether retrofitting is necessary and, if so, the failed components. The candidate retrofit measure is then incorporated into the bridge model, and the analysis is performed again.

RESULTS from both cases in the form of displacement and force-time history plots are presented and discussed, and the performance of the retrofit measure is evaluated.