PROBABILISTIC DEMA ND ASSESSMENT OF SEISMIC B ASE-ISOLATED STRUCTURES IN OMM EDIATE OCCUPANCY PERFOR MANCE LEVEL

Evaluation of isolated struct ures in the form of Performance-Based design framework would make greater understanding of behavior such these structures and give a quantitative idea about regulation's adequacy in preparing safety margin under extreme loadings especially in performance objects with lower damage states. Seismic demand analysis of Base-Isolated special moment steel Structures has been investigated in this paper. 4-, 6- an d 8-storey of three dimensional designed structures has been modeled in OpenSees Platform. The structur es were Analyzed and Designed based on A SCE 7-2010 standard, ANSI/AISC 360-10 and ANSI/AIS C 341-10 Specifications and some two dimensio nal frames were adopted from these archetypes for Evaluatio n of the performance objective. Various Source of Nonlinearity such as Material and Geometric Nonlinear ities have been Intended in Finite Element M odels. To consider the uncertainty in one hand and create comprehensive fragility curve on the other hand, Incremental Dynamic Analysis (IDA) using Far Field Gro und Motions Set has been utilized. The structure performance would be presented in terms of "fragility curvves" and "limit state frequencies" for immediate occupancy performance object. Results show that the mean annual frequency of models are much lower tha n the Fixed-base ones. It can be observed that the ASCE 7-2010 Standard can provide a uniform risk in mod els with various type of configuration too.

کلیدواژه ها:

Seismic Isolation ، Perfo rmance-Based Design ، Fragility Curves ، Incremental Dynamic Analysis ، Immediate Occupancy Performance Level