Behaviour factor of buckling restrained braced structures for near and far fault ground motions

Abstract

In common structural design codes, behaviour factor (R factor) is used to reduce earthquake design loads by taking advantage of nonlinear behaviour of structure during seismic events. There are some analytical approaches to evaluate behaviour factor using the results of incremental dynamic analysis (IDA) method. Using such methods, the variation of R factor values for different types of ground motions (near-fault and far-fault) can be investigated. Regarding the effect of near fault ground motions on ductility capacity of structures, R factor values are expected to be sensitive to the type of earthquake record. This issue is investigated through evaluation of R factor for three buckling-restrained braced frames (BRBF) for two sets of ordinary and near-fault ground motions. The results demonstrate that behaviour factor of BRBF structures is considerably lower for near-fault ground motions, compared to ordinary records. This is very critical for design of structures in near fault regions.