Rigid-Body Motion of Horizontally Curved Bridges Subjected to Earthquake-Induced Pounding

Horizontally curved bridges have been observed to suffer severe structural damage during past earthquakes. Unseating of the deck from abutments is one of the typical modes of failure of horizontal curved bridges. This type of failure is caused primarily because of excessive in-plane rigid-body motion of decks of these bridges, mainly due to the irregular geometry of the bridge itself and seismic pounding between the deck and abutments. This paper investigates the influence of seismic pounding on rigid-body motion of horizontally curved bridges during strong earthquakes using an analytical approach. For this purpose, a 3-degree-of-freedom nonlinear model has been developed to capture main dynamic parameters affecting seismic response of horizontally curved bridges. The accuracy of this model has been verified by finite-element modeling of a typical horizontal curved bridge. An extensive parametric analysis has been performed by varying key parameters, including the size of the gap between the deck and abutments, the subtended angle of the deck, and the presence of friction. Numerical results show that in-plane response quantities of horizontally curved bridges, such as radial and azimuthal displacements of corners of the deck and rotation of the deck about the mass center, are affected noticeably because of seismic pounding. Validity and reasonableness of seismic design guideline recommendations for regular curved bridges in the presence of seismic pounding have also been investigated.