车辆-模数式伸缩缝耦合振动与冲击荷载分析

为研究导致伸缩缝及其相邻路面损坏的车轮冲击荷载，以桥梁工程中常用的模数式伸缩缝为例，提出一种车辆-桥梁-模数式伸缩缝耦合振动的分析方法。该方法通过分布式弹簧阻尼单元模拟车轮在伸缩缝上的脱空情况；采用等效悬臂或两侧支撑梁模型，考虑脱空段轮胎面的支撑作用，通过车辆-桥梁-伸缩缝耦合振动的迭代算法，实现模数式伸缩缝上的车轮动力荷载的准确模拟，并对载重汽车通过双缝模数式伸缩缝进行实例分析。研究结果表明：①由于伸缩缝结构和车轮位置的变动，很难保证车辆振动的对称性，因此需要采用三维有限元方法分析车轮冲击荷载；②伸缩缝空隙处轮胎面的支撑有助于减小车轮冲击荷载，该支撑刚度与胎面预拉应力密切相关，胎面预拉应力越大，支撑刚度越大，轮载冲击系数越小；③车辆不对称振动导致左右轮冲击系数不同，模数式伸缩缝的中梁跨中冲击系数最大；④模数式伸缩缝上的轮载冲击系数计算值可能超过中国伸缩缝设计指南规定值，该方法可用于确定模数式伸缩缝的最大容许间隙，使车轮冲击荷载小于设计值，以保障伸缩缝的安全服役。

Analysis of Impact Load and Coupling Vibration of Vehicle and Modular Bridge Expansion Joint

To study the impact load of a tire causing the expansion joint and its adjacent road surface damage, a computational method is presented for the analysis of coupling vibration of vehicle, bridge, and modular bridge expansion joint (MBEJ) commonly used in bridge engineering. A distributed spring-damper element was used to simulate the tire structure over the cavities of the MBEJ. The equivalent cantilever or two-sided support beam model was adopted to consider the support of the tire tread in the cavity sections. An accurate simulation of the tire dynamic load on the MBEJ was realized using an iterative algorithm of coupling vibration of vehicle, bridge, and expansion joint. The analysis of a heavy vehicle across the twin-gap MBEJ shows that: ①The symmetry of the vehicle vibration is difficult to obtain owing to the changes of the expansion structure and tire position, and hence, the three-dimensional finite element method is required to analyze the tire impact load; ②The support of the tire tread at the cavities of the expansion joint can help reduce the tire impact load, and the supporting stiffness is closely related to the pre-tensioning stress of the tread. As the pre-tensioning stress increases, the supporting stiffness increases and the impact factor of the tire load decreases; ③Asymmetric vibration of the vehicle results in different impact factors of left and right tire loads, and the maximum impact factor is observed at the middle of the center beam of the MBEJ; ④The calculated impact factor of the tire load on the MBEJ may exceed the value specified in the Chinese design guide for expansion joints. The maximum allowable gap width in the MBEJ can be determined using the current method, such that the impact tire load can be controlled to be less than the design value and to assure the safe service of the MBEJ.