简支梁桥上嵌入式轨道无缝线路可靠性分析

为分析关键因素对桥上嵌入式轨道无缝线路力学特性的影响, 并基于可靠性理论对其进行评估, 采用有限元法建立了简支梁桥上嵌入式轨道无缝线路计算模型, 选择高分子材料纵向阻力和梁体温差为随机变量, 并根据实际工况确定了随机变量的分布类型和分布参数; 通过中心组合试验设计方法设计了响应面试验, 采用最小二乘法拟合了随机变量和响应之间的函数关系, 从而建立了轨板相对位移关于高分子材料纵向阻力和梁体温差的二次多项式响应面模型, 通过方差分析验证了所建立模型的正确性, 并采用灵敏度分析方法对随机变量进行了参数敏感性分析; 构建了桥上嵌入式轨道无缝线路长期服役性能的极限状态方程, 综合运用蒙特卡洛法和响应面模型评估了简支梁桥上嵌入式轨道无缝线路的可靠性。分析结果表明: 梁体温差和高分子材料纵向阻力对轨板相位移的灵敏度系数分别为0.99和-0.08, 梁体温差对轨板相对位移的影响远大于高分子材料纵向阻力; 在考虑参数的随机性以后, 温度作用下的轨板相对位移具有一定的离散性, 其主要分布在4.0~6.5 mm范围内, 且近似服从正态分布; 在不采取特殊处理措施的情况下, 不宜在年温差较大的地区建造桥上嵌入式轨道; 提出的桥上嵌入式轨道无缝线路可靠性评估方法可为嵌入式轨道结构的设计提供理论指导。 

Reliability analysis of embedded track continuous welded rail on simply supported beam bridge

To analyze the influences of key factors on the mechanical characteristics of embedded track continuous welded rail on bridges, and evaluate it based on the reliability theory, the finite element method was used to establish the calculation model of embedded track continuous welded rail on the simply supported beam bridge. The longitudinal resistance of polymer material and the temperature difference of beam body were selected as the random variables, and the distribution types and distribution parameters of random variables were determined according to the actual working conditions. The response surface test was designed by the central composite test design method. The function relationship between the random variable and the response was fitted by the least square method. Thus, the quadratic polynomial response surface model of track-bridge relative displacement with respect to the longitudinal resistance of polymer material and the temperature difference of beam body was established. The correctness of the established model was verified by the variance analysis, and the parameter sensitivities of random variables were carried out through the sensitivity analysis method. The limit state equation of long-term service performance of embedded track continuous welded rail on bridges was constructed. The reliability of embedded track continuous welded rail on the simply supported beam bridge was comprehensively evaluated by using the Monte Carlo method and the response surface model. Analysis result shows that the sensitivity coefficients of temperature difference of beam body and longitudinal resistance of polymer material to the track-bridge relative displacement are 0.99 and-0.08, respectively. Therefore, the influence of temperature difference of beam body on the track-bridge relative displacement is much greater than that of the longitudinal resistance of polymer material. After considering the randomnesses of parameters, the track-bridge relative displacement under the action of temperature has a certain dispersion, mainly distributes in the range of 4.0-6.5 mm, and approximately follows the normal distribution. In the absence of special treatment measures, the embedded track on bridges should not be built in areas with large annual temperature difference. The proposed reliability evaluation method of embedded track continuous welded rail on bridges can provide a theoretical guidance for the design of embedded track structure.