Effect of earthquake-induced transverse poundings on a 32 m span railway bridge isolated by friction pendulum bearings

To reduce the seismic force transmitted between piers and girders, friction pendulum bearings have been widely used in bridge structures. However, the bearings will lead to large relative displacements between the girder and the pier and thus increase the pounding potential of adjacent bridge structures. In the transverse direction, the girder movement can only be limited by shear keys. In this study, a series of shake table experiments were performed on a 1/6-scaled bridge model. To evaluate the consequences of poundings for isolated bridges, the wavelet transform (WT) is applied in addition to the fast Fourier transform (FFT). WT transform is used to capture the change in frequency content at the time of impact, while FFT is used to visualise the change in the frequency content of the entire response. Four different gap sizes and El-Centro earthquake with two different peak ground accelerations were considered. The results show that the selected gap size is relevant to the overall performance of the bridge.