Development of a novel cost-effective toggle-brace-curveddamper (TBCD) for mid-rise steel structures using multi-objective NSGA II optimization technique

Curve-shaped laser-cut steel plate dampers named curved damper have been recently introduced, and their performance has been experimentally investigated through cyclic loading tests. Using the same concept, this study aims to propose a novel cost-effective toggle brace–curved damper (TBCD) system, which combines the toggle braces and curved dampers to provide a practical passive control device. The seismic performance of three-, six-, and nine-story steel moment–resisting structures utilized with TBCD is analyzed using nonlinear time history analysis (NTHA). For better comparison, the TBCD system is optimized using the multi-objective nondominated sorting genetic algorithm (NSGA-II). The seismic performance of the proposed system is then compared against the optimized viscous dampers (VDs), viscoelastic dampers (VEDs), and buckling-restrained braces (BRBs). The results of the optimization process show that the TBCD has comparable performance to the other passive control devices presented, while it leads to more cost-effective design solutions by reducing the constructional, installation, life cycle maintenance and repair cost, and downtime. Hence, the proposed TBCD system can be considered as an efficient alternative to conventional seismic force–resisting systems for both newly built structures and the seismic retrofitting of existing structures.