曲线箱梁桥的车桥相互作用分析

ANALYSIS OF INTERACTION BETWEEN VEHICLE AND BRIDGE WITH CURVED BOX GIRDERS

针对公路和城市立交中的曲线箱梁桥,基于剪力柔性梁格法建立了曲线箱梁的梁格模型,进行了车桥相互作用分析。采用三角位移函数,基于平衡法推导了一种新型曲梁单元。利用曲梁的力-位移关系,得到了极坐标下空间曲梁单元的刚度矩阵和一致质量矩阵。根据拉格朗日定理,建立了7自由度空间车辆模型。采用逆傅立叶变换法,由功率谱密度生成了4种等级的桥面不平度。数值仿真了一混凝土单箱双室曲线连续箱梁桥的动力特性和车桥相互作用,并分析车辆横向位置、车速、桥面不平度、曲率半径等因素对桥梁冲击系数的影响。结果表明:该曲梁单元简便、实用,所建立的曲梁梁格模型可以准确地模拟曲线箱梁桥的车桥相互作用。

Against the curved box girder bridges in highway bridges and urban viaducts, the curved grillage model of the multi-cells curved box girder is built in terms of the shear-flexible grillage method, and the analysis for the vehicle-bridge interaction is performed. The trigonometric function is introduced as element＇s displacement function, and a novel curved beam element is derived using equilibrium equation. Based on the force-displacement equations of curved beam, both the stiffness matrix and consistent mass matrix of spatial curved beam element in polar coordination are deduced. A spatial vehicle model with seven degrees of freedom is established according to the Lagrange principle. The inverse Fourier transforms is used to generate four grades of road irregularity according to power spectral density of road roughness. The dynamic character and vehicle-bridge interaction of a concrete continuous curved box girder are numerically simulated, and the influence of the vehicle position, vehicle speed, road roughness and curvature radius on the impact factor is investigated. The results show that the curved beam element has more powerful computational efficiency and practicality. The interaction between vehicle and bridge with the curved box girder can be exactly simulated by the curved grillage model developed in the paper.