A Study on Development and Comparison of Seismic Design Methods based on Force-Based Design, Displacement-Based Design and Force-Displacement-Based Design for Road Bridge-RC Piers

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Main results obtained in this study are as follows :1. As for the inelastic response spectra relating to the seismic design methods :(1) Average acceleration response spectrum for every twelve acceleration wave differ widely among the Level 2 simulated earthquake motion specified in the Japanese Specification, the one satisfying attenuation relationship of maximum ground motions and recorded earthquake motion in Hyougoken Nanbu Earthquake.(2) Difference in the earthquake Type, soil Group, characteristics of SDOF system (restoring force model, ultimate ductility, plastic rigidity, etc.), required value Dr of modified Park-Ang's damage index and positive coefficient β in the index affects value and shape of the (mean+ σ) inelastic response spectra for every twelve Level 2 simulated earthquake motion specified in the Japanese Specification.(3) Consequently, it is essential to pay enough attention to the difference in the (2) above when we derive the inelastic response spectra for seismic design.2. As for the seismic design method :(1) Three design methods, that is, 1) force-displacement-based design method, 2) displacement-based one and force-based one are developed by the use of inelastic acceleration-displacement response spectrum, displacement spectrum and appropriate seismic force and acceleration spectrum, respectively.(2) Design result of the methods 1) and 2) for road bridge-RC piers on the Group II soil and subjected to Type II earthquake motion, requires larger value of ultimate ductility than that of the method 3) and ductility design method in Japanese Specification. This result means that the former methods 1) and 2) taking account of displacement response spectrum in the design criteria become safer method than the latter ones.(3) Design earthquake force calculated obtained from inelastic acceleration spectrum shows larger value than that of the ductility design method, based on energy constant law.