Elaborate Simulation and Prediction of Seismic





INTRODUCTION

After the 1995 Kobe earthquake, many research efforts in Japan are attracted on the improvement of seismic design methodology based on dynamic analysis, and consequently some design procedures as well as practical analysis programs are proposed or improved for steel bridges (e.g., References [1]-[3]). Furthermore, in the latest Japan road design codes updated in 2002 (JRA 2002 [4]), the dynamic analysis is required for many practical design cases.



For such dynamic analysis, structural data such as stiffness and masses are formulated on design drawings or design statements. Moreover, the damping is assumed on this basis and the standard seismic ground motions specified in codes are employed as the input earthquakes. However, by using such analysis model and input ground motions, the responses obtained from the dynamic analyses could be quite different from the real responses of actual structures subjected to actual ground motions spread from the hypocenter. The reasons lie in that the measured characteristics of actual structure usually differ from those of the analysis model as mentioned above, which based on the nominal design data, and that the input ground motions are significantly influenced by the oscillating mechanism of hypocenter, the characteristics of spreading





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