Abstract
The purpose of this study is to devise a simple kinematic model representing overall behavior of a framed structure under earthquake excitations. The well-known fact is that an equivalent continuous system is a useful mathematical model to calculate responses of a framed structure composed of discrete members. Although many investigators have used such a model, most of the works have dealt only with elastic response analyses. Efforts are still insufficient to incorporate inelastic responses of a structure, which are undoubtedly important in the aseismic design. The authors showed in the previous paper (Part 1) that inelastic responses of a framed structure were strongly affected by the yield interaction between forces acting at a story. The present study develops a yield interaction equation that is a function of a story shear force, a story axial force, an overturning moment and transverse forces on the beams due to gravity and dynamic effects. From this equation an equivalent continuous system is devised, which is a mathematical model for an inelastic framed structure incorporating the effects of yield interactions between those forces, work-hardening of material and P-⊿ effect on whole story. Further, numerical examples are given. The results show that the proposed method gives reasonable approximations for overall responses of the structure such as a shear force and horizontal displacement of each story, as compared with a more accurate but complicated analysis. The present method may be applicable to seismic response analysis of multi-story framed structures.
