整体式斜交连续梁桥抗震性能

采用SAP2000软件建立了某整体式斜交连续梁桥的三维有限元模型，通过非线性时程分析，研究了整体式斜交连续梁桥在地震作用下的受力特性及抗震性能，并探究了跨数、斜交角、台后土密实度和墩高等主要结构及基础参数对该类桥梁地震响应的影响。研究结果表明:整体式斜交连续梁桥中震害变形主要集中于桥台桩，桩顶截面在峰值加速度为0.4g的地震作用下形成塑性铰时，墩顶支座无破坏，且桥墩几乎无损伤；桥台桩位移及纵桥向弯矩的最大值均位于桩顶，而横桥向弯矩最大值可能位于桩顶或桩身反向弯矩峰值处；随着跨数的增加，整体式斜交连续梁桥的地震响应尤其是墩顶支座剪切应变及桥面转角明显增大，当跨数由单跨增加到4跨时，地震响应均增加了1倍以上，墩顶支座剪切应变甚至增加近2倍；随着斜交角的增加，桩顶纵桥向位移、桩顶截面屈服面函数值及中跨转角明显增大，斜交角为60°时，桩顶纵桥向位移增加了3倍以上，斜交角为45°时，墩顶支座剪切应变最大；随着台后土密实度的增加，各构件纵桥向位移响应与墩顶支座的纵向剪切变形降低，桥台桩、桥墩纵桥向位移及墩顶支座纵向剪切变形分别减小了12.9%、9.3%和9.5%；随着墩高的增加，墩顶位移明显增加，而支座剪切应变明显降低，但桩顶位移及桩顶截面屈服面函数值几乎不变；当墩高从4 m增大到9 m时，墩顶漂移率增大了42.1%，墩顶支座剪切应变减小了57.5%。 

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.