A note on compression strength reduction factor for a buckled strut in seismic-resisting braced system

摘要

This note has emerged as a result of developing deterministic pro- cedures for seismic design of braced steel frames. According to the capacity design procedure, braces are chosen as the primary seis- mic resisting elements, which produce the overstrength axial ten- sion and compression actions. These overstrength brace actions are then used to design the secondary elements such as beams, columns and connections. Fundamental to the capacity design philosophy is the need to be able to estimate the maximum design actions that secondary members in concentrically braced frames must be able to resist after the braces buckle. It appears that the maximum seismic actions in secondary members are dependent on the post--buckling strength of braces in a seismic-resisting sys- tem. The experimental data compiled from different sources were compared with the analytical expressions for the brace com- pression strength reduction factor employed by some seismic design codes. The levels of reduction in the brace compression capacity have been identified, and a new analytical expression for the brace compression strength reduction factor has been pro- posed.