Seismic behavior of integral skewed continuous girder bridges

A three-dimensional finite element model of an integral skewed continuous girder bridge was established by using SAP2000 software, and the nonlinear time-history analysis was conducted to investigate the mechanical properties and anti-seismic behavior of the integral skewed continuous girder bridge under seismic actions, and the influences of major structures and basic parameters on the seismic responses of this kind of bridge were explored, such as the number of spans, skew angle, compactness of soil behind abutment, and pier height. Research results show that the deformation caused by seismic damages in the integral skewed continuous girder bridge mainly focuses on abutment piles, and when plastic hinges are formed at the pile top under seismic actions with a peak ground acceleration (PGA) of 0.4g, the supports at the pier top and the piers are basically not damaged. The maximum values of abutment pile displacement and longitudinal bending moment are located at the pile top, while the maximum value of transverse bending moment may be located at the pile top or the peak of the reverse bending moment of the pile body. With the increase in the number of spans, the seismic responses of the integral skewed continuous girder bridge increase obviously, especially the shear strain of the supports at the pier top and the rotation angle of the bridge deck. When the number of spans increases from one to four, the seismic responses have doubled, and the shear strain of the supports at the pier top even increases nearly two times. With the increase in skew angle, the longitudinal displacement at the pile top, the yield surface function value of the cross-section at the pile top, and the angle of rotation in the middle span obviously increase. When the skew angle is 60°, the longitudinal displacement at the pile top increases more than three times, and the shear strain of the supports at the pier top is the largest when the skew angle is 45°. With the increase in the compactness of the soil behind the abutment, the longitudinal displacement response of all components and the longitudinal shear deformation of the supports at the pier top reduce. The longitudinal displacements of the abutment piles and piers and the longitudinal shear deformation of the supports at the pier top reduce by 12.9%, 9.3%, and 9.5%, respectively. With the increase in pier height, the displacement at the pier top increases significantly, and the shear strain of the supports decreases obviously, but the value of the displacement and yield surface function of the cross-section at the pile top is almost unchanged. When the pier height increases from 4 m to 9 m, the drift rate at the pier top increases by 42.1%, and the shear strain of the supports at the pier top decreases by 57.5%. 4 tabs, 18 figs, 32 refs.