Seismic risk-based optimal design of fluid viscous dampers for seismically excited nonlinear structures

This paper introduces a procedure to risk-based optimal design of fluid viscous dampers (FVDs). To this end, the exceedance probability of specific performance level during the design lifetime as a safety criterion of the entire building is intended to be minimized. This, along with the minimization of the total damping coefficient of FVDs as the cost criterion of the dissipation system, are the considered objective functions. The damping coefficient of FVDs have been considered as design variables and the efficient configurations of damper properties over the height of the building have been determined. A multi-objective optimization framework using the non-dominated sorting genetic algorithm version II (NSGA-II) has been employed to solve the optimization problems and determine the set of Pareto optimal solutions. Linear and nonlinear FVDs with different capacities have been designed for an eight-story shear-type building with bilinear elastic-plastic stiffness behavior under 20 real earthquakes. The results show that the optimal FVDs reduce the seismic response and fragility of the building, while limiting the dampers’ cost.