Time history analysis of axial forces (Pass Through Forces) at joints in a braced frame

Abstract

As buildings keep getting taller, traditional braced lateral systems take more loads. This generates a phenomenon at every joint of a frame called "Pass Through Force". Pass through forces come from the transfer of axial forces between two side by side members. Adding a bracing scheme to our frame will introduce even more pass through forces at the node since part the force in the bracing will be transferred in the horizontal member. The main goal of this thesis is to find an appropriate way of computing pass through forces without being too conservative. If we take an accurate value of pass through force at a node, the steel connections will not be overdesigned, resulting in cost savings. In this thesis, we analyse multiple bracing configurations for a typical steel frame under different load combinations in order to find a procedure for computing pass through forces adequately. Each scenario will be analysed in detail, a time history analysis will be used to find precise values under earthquake loading. The results are compared with two traditional methods of finding pass through forces, and the best approach is identified.