Performance-based optimal distribution of viscous dampers in structure using hysteretic energy compatible endurance time excitations

Performance-based optimization of energy dissipation devices in structures necessitates massive and repetitive dynamic analyses. In the endurance time method known as a rather fast dynamic analysis procedure, structures are subjected to intensifying dynamic excitations and their response at multiple intensity levels is estimated by a minimal number of analyses. So, this method significantly reduces computational endeavors. In this paper, the endurance time method is employed to determine the optimal placement of viscous dampers in a weak structure to achieve the desired performance at various hazard levels, simultaneously. The viscous damper is one of the energy dissipation systems which can dissipate a large amount of seismic input energy to the structure. To this end, hysteretic energy compatible endurance time excitation functions are used and the validity of the results is investigated by comparing them with the results obtained from a suite of ground motions. To optimize the placement of the dampers, the genetic algorithm is used. The damping coefficients of the dampers are considered as design variables in the optimization procedure and determined in such a way that the sum of them has a minimum value. The behavior of the weak structure before and after rehabilitation is also investigated using endurance time and nonlinear time history analysis procedures in different hazard levels.