Optimal Response of Isolated Multi-span Continous Deck Bridges Subjected to Near Fault and Far Field Events

The present study analyses the optimal friction coefficient for the seismic isolation of composite bridges, equipped with single concave friction pendulum (FPS) devices. The bridge is modelled through a six-degree-of-freedom system while the FPS friction property is described through a model that accounts for the dependency on the velocity. By introducing a time scale and a length scale, a nondimensional analysis has been used to solve the equations of motion. In detail, the response is analysed independently on the peak ground acceleration-to-velocity ratio. Furthermore, two different sets of seismic events are considered: far field and near fault. Then, many bridge models are analysed by changing different parameters (i.e., pier period, deck period, mass of the deck and of the pier and friction coefficient). By minimizing the substructure response, an optimum value of the friction coefficient is computed as function of the ratio between the period of the deck and the period of the seismic input.