Nonlinear response spectrum analysis of structures equipped with nonlinear power law viscous dampers

چکیده مقاله

Old steel arch bridges commonly need rehabilitation interventions because of their insufficient lateral resisting capacity against seismic loads.A punctual strengthening method is not applicable for such bridges in most cases because of high costs and the lack of convenient access to the structural members. This leads the designers toward the reduction of seismic demands using base isolation systems. However, replacement of the existing arch supports with base isolators isextremely difficult and risky. As an alternative and convenient retrofitting method, in this study the energy dissipation systems in the form of nonlinear viscous dampers (NVDs)are localized within the end bracing members of the arch. A series of numerical analyses are performed on a benchmark steel arch bridge subjected tosix earthquake records. The analyses are performed using Incremental Dynamic Analysis (IDA) methodin order to investigate the effect of damper nonlinearity under increasing excitation levels. The results show that, regardless of the considered earthquake excitation, the base shear tends to a definite value depending on the NVD mechanical specifications. Based on these results, the NVDcharacteristics can be suitably adjusted so that the seismic demand lies within an acceptable range for the existing structural members.