Displacement Coefficient Method for Bridge subjected to Pulse-Like Ground Motions

This paper proposes the displacement coefficient, R-d, for bridge column subjected to near-fault earthquake. R-d is defined as a ratio between ultimate displacement and elastic displacement. 142 pulse-like ground motions are utilized to perform the nonlinear time history analysis with constant ductility from 1 to 6. This study investigates the R-d in four aspects, including (1) signal processing method, (2) orientation of the velocity, (3) hysteretic models, and (4) number of the ground motions. The analytical results are compared with the regulations specified in AASHTO 2011. For a structure with typical displacement ductility of 4, compared to the analytical results, the R-d in AASHTO 2011 is overestimated within the period of 0.5 second, and underestimated between 0.5 and 4 second. Therefore, the revised formulation of R-d is proposed, which could be suitable for the bridge considering the near-fault effect in Taiwan.