Near-source ground motions effect on seismic reliability of reinforced concrete framed buildings

Near-Source ground motions have characteristics like pulse-like feature which make them distinctive from ordinary records. This paper discusses near-source ground motions effect on seismic reliability of reinforced concrete framed buildings. Since there are significant uncertainties in capacity of structural members and seismic excitations, reliability analysis can be an efficient method for assessing the seismic performance of a structural system. In this study the reliability evaluation is carried out by response analysis. Nonlinear dynamic analysis is used for assessment of structural seismic demands. Two sets of ordinary and near- source records are selected for focusing on comparison of near source ground motion effects with ordinary ones. A vector-valued intensity measure (IM) is adopted for applying the ground motions, which takes into account the spectral shape. Four example buildings with different heights are analyzed through three-dimensional nonlinear time history method, and capacity curves are obtained by incremental dynamic analysis (IDA). The P-Delta effect was considered in nonlinear analysis. In considering the effect of added shear walls on structural seismic reliability in near-source ground motions, the example buildings had two different kind of lateral load resisting systems, moment resisting frame system (MRF) and dual system consisting of moment resisting frames and shear walls. These approaches lead to a more general conclusion about the probability of failure of reinforced concrete framed buildings in near-source ground motions in comparison with ordinary ground motions. The results show that the added shear walls have a little effect on seismic reliability of high-rise reinforced concrete framed buildings subjected to near-source ground motions, but the added shear walls are relatively more beneficial for low-rise buildings against near-source ground motions.

Keywords:

Near-source effects , Seismic Reliability , Vector-valued IM , IDA , P-Delta effect