地震力に対する機器・配管系の弾塑性応答評価法（一自由度系の弾塑性応答特性の考察）

Abstract

A constant ductility response spectrum (CDRS) readily provides the yield strength of a single-degree-of-freedom (SDF) system necessary to limit the ductility imposed by a ground motion to a specified value. The allowance of inelastic deformation of an SDF system leads to reduction of the required yield strength. In this study, we discussed inelastic behavior of SDF systems located on floors by investigating CDRS for floor motions (CDFRS) amplified by the structures. We indicate that the reduction of the required yield strength depends on three effects; strength increasing, deformation increasing and hysteresis damping with increasing value of the ductility factor, and the required yield strength becomes less sensitive to the natural period of the system. We also indicate that the second stiffness of a system doesn't strongly affect the required yield strength. Based on these results, we propose a simplified method to obtain the yield strength of an SDF component necessary to limit the ductility imposed by a floor motion to a specified value by using the CDFRS.