鋼構造骨組の耐震設計用動力学モデルに関する研究 : その 1・鉛直地動が地震応答に及ぼす影響に関する一考察

Abstract

As the basic research for the study of developing a kinematic model, the investigation reported in this paper is an attempt to clarify the effect of vertical ground motion on the seismic response, which is usually ignored in current earthquake resistant design practice. To examine the effect of vertical ground motion on the seismic response, the inelastic response of steel frames subjected to the combination of horizontal and vertical components of the earthquake was compared with that to a horizontal components of the earthquake. The inclusion of vertical ground motion can result in a significant increase in the ductility requirements of the upper story members, of which the design is controlled by the vertical loading. It also seems to be probable that the inelastic deformation of the lower story columns in high-rise building may be affected by vertical ground motion in terms of increasing axial forces. It is concluded that effects of vertical ground motion on the seismic response are large enough to warrant consideration in earthquake resistant design practice. It should be noted that the inelastic interaction between horizontal inertia forces caused by horizontal ground motion and vertical inertia forces by vertical ground motion may play an important role to explain the effects of vertical ground motion on the seismic response.