In this study, the seismic capacity of a hybrid damper, composed of a steel slit plate damper and two shape memory alloy bars, is investigated through fragility analysis and life-cycle cost evaluation of a steel frame retrofitted with the damper. The nonlinear time history analysis model frames show that the seismic responses of the frames equipped with hybrid damper are significantly lesser than the frames retrofitted with conventional slit dampers. The enhancement in the seismic performance of frames retrofitted with hybrid damper is because of extra stiffness, energy dissipation, and self-centering capability provided by the shape memory alloy bars. It is also observed that the life-cycle cost of the frames equipped with hybrid dampers is smallest compared with the life-cycle cost of the bare frames and the frames equipped with slit dampers, even though the initial cost is of the hybrid damper is higher than that of the conventional slit damper.

No abstract

No abstract

No abstract

In this study, the seismic performance of a rotational friction damper with restoring force is presented. The torsional spring friction damper consists of rotational friction pads with the heavy duty torsional springs attached on both sides of the friction damper. An analytical model and a design procedure for the damper are developed using capacity spectrum method. A parametric study is carried out to investigate the influence of the torsional spring in the response of the structure when subjected to ground motions. The seismic performances of steel structures retrofitted with the torsional spring friction damper and conventional rotational friction dampers are evaluated using fragility analysis, which shows that the structure retrofitted with the torsional spring friction damper has the smallest probability of reaching the specific limit states.