斜拉桥主梁梁端轨梁相互作用机理及计算方法研究

The rotational angles and expansion displacements at girder ends of cable-stayed bridges under temperature varieties and trains are so significant that they could affect the serviceability of the track structures and even endanger running safety of the trains. Reasonable track-bridge interaction analysis is required to find good solutions for these problems. However, former investigations usually ignored the effect of loading rate and vertical wheel loading on longitudinal resistance of tracks, lacked the daily temperature model for cable-stayed bridges, neglected loading history of various loads and disregarded dynamic effect caused by moving or braking trains, leading to either investment waste or potential safety hazard..The proposed project aims to develop a new track-bridge static-dynamic interaction analysis method to overcome defects within the traditional ones. The elastic-plastic longitudinal resistance models of fastenings for ballastless tracks will be proposed in terms of static temeperature induced effect and dynamic train induced effect, based on laboratory experiments. The daily temperature model for typical double-deck steel truss cable-stayed bridges will be obtained by field tests. Finite element method will be used to establish the track-bridge static-dynamic interaction system models. The temperature induced responses of the interaction system will be first calculated considering loading history of seasonal and daily temperature varieties. And then the dynamic responses caused by the moving or braking trains will be computed regarding the temperature induced responses as the initial conditions. The mode superposition method and pseudo force method will be applied to enhance the dynamic compuation efficiency for the nonlinear system. The total responses of some practical track-bridge systems under temperature varieties and trains will be obtained using the proposed method, and the results will be compared to those obtained by the traditional methods. Consequently, the characteristic of the responses of the track structure in the vicinity of the girder ends can be analyzed and the mechanism influencing the responses can be discovered. The research outcomes of this project can be utilized for optimal design, normal service and safe operation of the cable-stayed bridges and the track structures on them.

温度和列车作用下斜拉桥梁端转角与伸缩变位是导致轨道结构失效并危及行车安全的控制因素，需依靠科学的轨桥相互作用分析来寻找合理解决策略。目前研究不考虑加载速率及动态轮压对线路纵向阻力的影响，缺乏斜拉桥日温差取值依据，不计多种荷载加载历程对轨桥非线性系统的影响，忽视车致动力效应，导致投资浪费与安全隐患并存。.项目基于室内试验提出温度静载及列车动载下无砟轨道扣件纵向阻力弹塑性模型，利用现场实测建立典型双层桥面钢桁架斜拉桥日温差模型，采用有限元法建立轨桥静动力相互作用模型，计算其在温度循环加载历程下的累积响应，在此初始条件下，运用模态叠加法和拟力迭代法计算列车匀速通过或制动下的动力响应，从而得到模拟加载历程的非线性系统总响应。将这一改进算法与传统方法应用于实例分析，对比分析梁端轨道结构响应特征及蕴含的影响机理，提出相应控制策略，为斜拉桥及桥上轨道结构匹配设计、正常使用及安全运营提供理论支撑。

首先在试验室内对DT-2、WJ-2、克隆蛋三种扣件进行了有载和无载的情况下的位移阻力系数的试验，根据试验结果分析了钢轨位移阻力系数滞回特性和有载到无载之间变化规律，提出了能反映轨梁相互作用的位移阻力系数的双弹簧模型，该模型纠正了德国学者P.Ruge and C.Birk等人的位移阻力系数模型一些不合理的假定，更加符合实际情况，具有创新性和先进性。.其后，根据获得的轨梁位移阻力双弹簧模型，在简支梁体系内进行了考虑加载历程的钢轨附加力的计算，并和传统的线性叠加方法对比。分析表明：由于梁轨作用问题是一个复杂的非线性问题，必须考虑荷载反复作用下的钢轨残余应力，它对附加应力计算结果产生较大的影响。按加载历程方法计算的钢轨附加应力比线性叠加法小，而轨梁相对位移要大很多。对斜拉桥进的计算分析得出了相同的结论，但是位移差值要更大些。斜拉桥钢轨附加力和梁轨相对位移最大值位于斜拉桥两边墩处，数值计算结果和试验数据吻合。钢轨附加力主要与斜拉桥结构体系有关，和主梁刚度大小关系不大，对塔梁固结体系，钢轨附加应力将变得很小。.移动车辆制动和启动作用下梁轨相互作用属于动力问题，目前都用静力方法计算。课题组针采用移动车辆荷载过桥方式，对斜拉桥钢轨在制动和启动作用下的附加应力进行动力计算，并将结果与静力学计算数据进行了比较，结论是两种方法计算结果相差不大，可以用静力方法来计算制动作用下的梁轨的相互问题，回答了这个长期争议问题。.斜拉桥结构温度场对钢轨温度附加应力影响研究表明：拉索、桥塔、墩台和钢轨虽然具有不同的温度分布，但拉素、桥塔、墩台和钢轨的温差产生的钢轨温度附加应力影响不大，可以不予考虑，影响钢轨温度附加力的主要因素是梁轨的温差。对轨道U梁和钢轨温度场进行了大量测试，并应用热力学理论进行日照作用下温度场分布计算研究。研究发现，目前梁轨温度附加应力计算的假定和实际出入太大，梁内温度场不宜采用单一温度值和平面假定来计算。研究发现采用热力学理论计算日照下温度场和现场实测吻合，可以用来计算梁轨温度附加应力。.最后，对斜拉桥钢轨伸缩调节器设置的合理跨进行了研究。分别建立了303 m, 454.5m, 606 m, 757.5 m, 909 m, 1060.5 m的轨道交通斜拉桥模型，研究必须设置钢轨调节设置的合理跨度。此项研究已有一些初步结论，可作为后续研究。