Knee elements are elements dissipating energy in knee-brace-frames and their design parameters have great influence on the earthquake-resistant performance of knee-brace-frames.

A structural model of buckling-restrained braced frame is set up,and its seismic properties(including model analysis,time-istory and pushover analysis) with finite element software SAP2000.

Brace design of K shape eccentrically braced steel frames;

Collapse Mechanism and Design Criteria of Eccentrically Braced Steel Frames under Cyclic Load;

The numerical example shows that it has simple concept and convenient calculation for solving cross-section optimization design of eccentrically braced steel frames,as well as provides the better approach to real optimization design.