When a continuous PC rigid frame bridge is subjected to fault displacements, response such as deflection, curvature, moments and so on are obtained differently if torsional rigidity is evaluated differently. Effects of torsion have not been considered strictly in seismic design code, therefore the evaluation of torsional rigidity is not rational. This paper presents the results of push over analysis of a continuous PC rigid frame bridge subjected to fault displacements in transverse direction, and clarifies the effect of evaluation of torsional rigidity on seismic performance of bridges. The necessity of adequate evaluation of torsional rigidity is discussed using moment torsion correlation curves.
