Effect of revised design earthquake ground motions considering zones factors on nonlinear response of steel bridge piers

In 2012, Level 2 Earthquake Ground Motions (Type I) and 'modification factor for zones (zone factor)' in the seismic design specifications for highway bridges in Japan were revised. Design earthquake ground motions should be multiplied by zone factors to evaluate the seismic performance. Regarding one of zones, Type I design earthquake ground motions are remarkably changed from the former earthquake ground motions multiplied by "0.85" to the revised ones multiplied by "1.2". The purpose of this paper is to investigate the effect of design earthquake ground motions considering zone factors on nonlinear response of steel bridge piers. The time-history dynamic analysis on the single-degree-of-freedom system was adopted in order to identify whether the bridges have enough seismic performance. Comparing obtained maximum response displacements of two kinds of earthquake ground motions (Type I and Type II), this paper came to conclusions. The results revealed that, regarding some zones, the Type I design earthquake ground motions have generally caused larger maximum response displacement than that of Type II.