Seismic Displacement Estimates for Bridges in the New Madrid Seismic Zone

AbstractThe Mississippi embayment (ME) of the New Madrid seismic zone (NMSZ) is characterized by deep soil deposits. This places much of the ME outside the realm of code-based spectral shape assumptions. Only the top 30 m of the subsurface profile is used as input for developing current code-based response spectra. Rules for effective damping and response modification for effective damping vary depending on the structure type—conventionally designed plastic hinging or isolation design. The goal of this study was to build on previous research and propose an alternative, rational method for including each of these effects—profile depth, effective damping, and response modification for effective damping—into the development of seismic displacement estimates for bridges in the NMSZ. Displacement estimates for a bridge near Memphis, Tennessee, for both conventional design and isolated design alternatives, were made using both code-based and alternative criteria. The bridge was moved to five other sites of vari...