Progressive collapse dynamic analysis of concentrically braced steel frames

To study the dynamic effect of concentrically braced steel frames during progressive collapse, instantaneously applied load method was employed to perform the elastic-plastic dynamic response analysis of five common kind of concentrically braced steel frames with the failed middle and side column. The analytical results show that: the ultimate load capacity of steel frames is not improved by using no matter which kind of braces while the stiffness is increased significantly. The displacement of the failure point in K-braced, V-braced and inverted V-braced steel frames with a failed middle or side column are reduced significantly. The stiffening effect of forward-brace in the steel frame with a failed middle column is better than the steel frame with a failed side column. The influence of backward-brace is approximate in both situations and inferior to other kinds of braces.