Seismic assessment of chevron braced frames with differently designed beams

Abstract

Braces in chevron braced frames inevitably suffer large cyclic deformation in the case of severe earthquakes. In a chevron braced frame, one brace buckling and another brace yielding would induce the unbalanced resultant force to braced beams. Capacity design requirements of braced beams in current codes suggest that braced beams totally bear the unbalanced resultant force. However, this requirement causes an excessively large cross section of braced beams and inhabits the application of Special Concentrically Braced Frames. Recent researches show that SCBF with yielding braced beams might also have satisfied seismic performance. To study the effect on seismic performance of concentrically braced frames with different beam strength and stiffness, numerical analysis including pushover analysis, hysteresis analysis and incremental dynamic analysis are conducted in this paper. Different slenderness of braces and different stiffness of braced beams are taken into consideration in the analysis. The results show that the seismic performance of braced frames with 1/3 brace resultant force-bearing beams is similar to braced frames designed by current codes.