Abstract:A new idea was proposed for obtaining a braced frame with better seismic performance. Firstly, the horizontal equivalent load was firstly obtained by the static equivalence of the maximum seismic effect derived from nonlinear dynamic time history analysis for the low-level light steel frame with small column span. Secondly, the topology of the supports of the frame was optimized by BESO (Bi-direction Evolutionary Structural Optimization) method to obtain a rational support distribution under the combination of the horizontal equivalent load and the vertical load, which has more uniform stress and better seismic performance. In the optimization process, the elements on the position of beams or columns kept constant, and the force-transmitting skeleton was obtained through the bi-direction evolution with the element increase and decrease. After that, the skeleton was reconstructed into a frame with rational supports by the equal section members. Simultaneously, several support distribution schemes for such frames were designed according to the structural concepts derived from the optimization results. Lastly, the seismic performance of these frames with supports were compared by nonlinear dynamic time history analysis according to the lateral displacement of the top. The results show that the performance of the frames designed by the topology optimization is better than that of the corresponding braced frames by the structural concepts. Based on the above contents, the design recommendations are given for the support distribution of the frame of the low-rise light steel buildings.