Analysis on seismic performance of centrically braced steel frame

The basic design idea of centrically braced steel frame is to center the plastic deformation of steel braced frame on braces during strong ground motions. Braces are expected to have tensile yielding and compressive buckling to dissipate energy and other structural components are needed to keep elastic. In order to analyze vibration property of steel frames with different pattern of braces, 12-layers lightweight centrically braced steel frame with three patterns as X braces, V braces and inverted V braces were designed utilizing PKPM software, providing the dynamic characteristics of the main components' size and structure, finite element analyses on these structures were carried out by using ANSYS and SAP2000 to investigate the effects of brace pattern on structural stiffness; Then ANSYS was utilized to carry out nonlinear time history analysis of frequent earthquake and rare earthquake under EL-Centro wave and SHW2 wave, seismic performance of steel frame with different braces has been discussed. Results show that V braces and inverted V braces are close in improving dynamic characteristic of structures and more effective than X braces; X braces the displacement and story drift ratio are slightly smaller than those of V braces and inverted V braces. The analysis results can be used for reference in structure selection for project planner.