2 a systematic research is done on the lateral behavior of braced steel frame system and the nonlinear behavior of concentrically braced frames ( cbfs ) and eccentrically braced frames ( ebfs ) is analyzed 2对支撑体系的抗侧力性能进行了系统的研究,对中心支撑体系和偏心支撑体系的非线性性能进行了简化分析。