Optimal response of isolated bridges subjected to near fault seismic inputs

This work deals with the evaluation of the seismic performance of multi-span continuous deck bridges isolated with single concave friction pendulum bearings. A sixdegree- of-freedom system is modelled to represent the seismic behaviour of the bridge, while the friction pendulum device is modelled by including the non-linear dependency of the friction coefficient from the sliding velocity. The isolator is considered on top of the abutment and of the pier. Different bridge models are obtained by changing different properties (i.e., deck and pier masses and fundamental periods) within a parametric study. Then, for each of the bridge models, a non dimensional analysis is performed to normalize the equations of motion with respect to the ratio between the peak ground acceleration and the peak ground velocity and those equations are solved for a set of 40 near fault seismic inputs. The final goal is to elaborate an optimal value of the friction coefficient in order to reduce the seismic response of the pier.