Seismic analysis of steel concentrically braced frames with consideration of fling-step effect

Abstract

Near-field earthquakes with a fling-step effect cause a permanent displacement at the end of the displacement record, which can affect the response of structures. Fling step is induced by permanent static displacement of the ground that is noticeable in strike–slip faults. This effect is usually omitted from the main record using the standard processing methods and, thus, the fling-step effect cannot be considered to obtain seismic response of different structures. To investigate the effect of near-field earthquakes with the fling-step effect, 14 original (non-filtered) ground motions with different fling displacement are selected. The selected records are applied to special concentrically braced frame (SCBF) structures with 3, 6, 9 and 12 stories to cover most structural periods. To investigate seismic response of the structures, two main parameters including lateral displacement and story–drift ratio are selected. A nonlinear time history analysis is used to obtain the displacement and story–drift ratio responses. The results show that the fling-step effect has no significant impact on any of the considered structures, and its effect can be neglected in case of special concentrically braced frame structures.