Seismic Performance Enhancement of a Single-Bay Single-Story Steel STMF using Viscous Damper and Optimization Technique

The steel special truss moment frame (STMF) is one of the lateral resistant structural systems which provides higher lateral stiffness with relatively less weight as compared to conventional steel moment resistant frames. In this study, to have a seismic resilient structural system, the seismic performance of the STMF is enhanced by installing two viscous dampers as the bottom chords of the truss-girder at the side of beam-column connections. The properties of the viscous dampers are found using a well-defined optimization problem. The ratio of the residual roof displacement of the frame with viscous damper to that of without viscous damper is considered as the single objective of the defined optimization problem to be minimized. The maximum roof displacement and the maximum inter-story drift ratio of the STMF with viscous damper are considered as the optimization constraints to be less than those for the STMF without viscous dampers. The Particle Swarm Optimization (PSO) algorithm is employed to find the optimum solution. A single-bay single-story steel STMF is used as a numerical example. The results of the seismic evaluation of the optimally retrofitted STMF confirm that its seismic performance enhancement is provided by using the presented methodology.