Reduction of Seismic Acceleration Parameters for Temporary Bridge Design

Keywords:  Earthquake engineering, spectra, temporary bridge, seismic, earthquake, response acceleration, return period, AASHTO

Abstract: This report presents a simple and conservative method for developing seismic response acceleration spectra to be used in the design of temporary bridges. A method for modifying the response spectra used in the design of permanent bridges with spectral reduction factors is defined. The spectral reduction factors are used to reduce the response spectra corresponding to a 1000 year return period to one having an approximated 100 year return period.  This result was obtained by first grouping seismic data by geographic location and, alternatively, by magnitude of response spectra to develop spectral reduction factors. The seismic data analyzed in this report was collected from the United States Geological Survey’s (USGS) website. The report provides two spectral reduction factors proposed for consideration by design specifications, and a design example to illustrate the procedure.