بررسی رفتار غیرخطی قاب خمشی فولادی طراحی شده با روش پلاستیک بر مبنای عملکرد

Abstract

In conventional seismic design methods the performance of structure has not been considered in base shear estimation and structural drift as a measure of damage will be checked at the end of design stages. This weakness of force-based design (FBD) methods causes to special attention to performance based design. Performance-based plastic design (PBPD) is one of performance based design in which the desired damage level and plastic mechanism of structure are predefined in the beginning of design procedure, to estimate internal forces. It is expected that applying PBPD ends to a structural behavior with more compliance with desired mechanism. In this paper the priority of PBPD over FBD has been investigated. The PBPD and FBD methods are applied to design of four special steel moment frames of 4, 8, 12 and 16 stories. Nonlinear behavior of designed structures have been evaluated by push-over and nonlinear time history analyses. Analyses results show that PBPD frame have mechanism mode closer to assumed mechanism mode in design procedure. Another conclusion is that PBPD frame mechanism in push-over analysis is more ductile than FBD frame. Also it concluded that in PBPD frame, plastic hinges approximately distributed uniformly all over the structure. General reason of PBPD ductility improvement, versus FBD, is strength of columns which prevent undesirable mechanism.