Multi-performance oriented seismic design of viscoelastic dampers for structural retrofitting

Abstract

This study presents a design method for additional viscoelastic dampers (VEDs) to retrofit low to mid-rise reinforced concrete (RC) structures. Unlike existing methods, this method considers the structural seismic capacity redundancy ratio (SCRR) as the design objective and comprehensively evaluates the effects of additional VEDs on the bearing, deformation, and energy dissipation capacities of these structures. The additional VEDs designed by the proposed method simultaneously enhanced the structural SCRR and improved the uniformity of the displacement profile. Moreover, the method is easily applicable in the preliminary design of the VEDs. In this study, the variation indices before and after adding the VEDs are first defined for the structural SCRR and the three capacities mentioned previously. Then, evaluation methods for the variation indices are established through pushover analysis (POA). On this basis, closed-form expressions of the storage stiffness and damping coefficients of the VEDs are provided along with the design flow. The design method is applied to multi-degree of freedom (MDOF) structural models with vertical irregularities, following which the evaluation results of the variation indices are compared with those obtained from time history analysis (THA). The evaluation accuracy of the proposed method is analyzed by introducing a non-uniform distribution factor for the irregular structural models. The proposed method is verified to be able to improve the SCRR of the primary structures to near or beyond the target, except for some extreme situations.