In-plane rotation response of skewed simply supported bridges considering multi-point pounding effect

Previous earthquake events have shown that the in-plane rotation of skewed bridges can induce multi-point pounding at longitudinal expansion joints and transversely between the decks and shear keys. These pounding phenomena may result in damage to girders and excessive deck movement. To explore the interaction between multi-point pounding and in-plane rotation response of decks in multi-span skewed simply supported bridges under seismic excitation, simplified equations for estimating bi-directional pounding forces were derived based on the force equilibrium principle. Finite-element models of skewed simply supported bridges incorporating pounding effects were developed, and time-history analyses were conducted to investigate the influence of skew angle, expansion joint width, and shear key capacity on the seismic response of bridges. The analytical results demonstrate the accuracy of the simplified pounding force estimation equations. The interaction mechanism indicates a positive feedback loop between multi-point pounding and in-plane rotation response, in which the two phenomena mutually amplify the responses. Parametric analysis reveals that the maximum seismic response can occur at a skew angle of 30 degrees, an expansion joint width of 10 cm, or a shear key capacity exceeding 20 %. With increasing expansion joint width and shear key capacity, the multi-point pounding effect and in-plane rotation response can be mitigated. However, an excessive expansion width may induce greater deck displacements, and a higher shear key capacity can lead to damage in the piers.