Reliability-based sensitivity analysis of vehicle components with non-normal distribution parameters

Techniques from the perturbation method, fourth moment method, reliability-based design theory, and sensitivity analysis approach are employed to present a practical and efficient method for testing the reliability sensitivity of vehicle components with non-normal distribution parameters. With the condition that the first four moments of original random variables are known, the reliability sensitivity theory and cases are researched using the presented numerical method. The variation regularities of reliability sensitivity are obtained and the effects of design parameters on reliability of the vehicle components are studied. The sophisticated formulation provided in this paper is easily amenable to computational procedures. The respective program can be used to obtain the reliability sensitivity of vehicle components with non-normal distribution parameters accurately and quickly. The results obtained are perfect and the solutions compared very well with those from Monte Carlo simulation. The method presents a theoretic basis for the reliability design of the vehicle components.     

漯河市泰山路沙河大桥病害成因及加固

该文以漯河市泰山路沙河大桥为例,针对中承式拱桥在运营十多年后,出现的各类病害进行分析,及加固处理。     

山区高速公路桥面铺装破坏形式及成因分析

通过对重庆市多条高速公路桥面铺装典型病害的调查和统计,分析了山区高速公路常用桥面铺装的病害成因,为防治山区高速公路桥面铺装的病害提供参考和借鉴。     

浅析桥梁防腐涂装方法和施工质量控制

该文分析了桥梁的腐蚀环境和腐蚀特点,通过对海口市和平桥防腐涂装技术研究和应用,提出一些合理的混凝土和钢结构桥梁防腐涂装的方法,并对涂装体系的施工工艺和质量检测控制进行了探讨。     

多点支撑加固坦拱桥试验研究

以多点支撑加固坦拱桥技术原理为依据,在完成2片模型试验拱的制作、加固前后测试的基础上,对比分析了圬工坦拱多点支撑加固增强处治前后主拱的应变、挠度、裂缝控制、破坏形态、极限承载力及支撑纵向钢筋应力指标.从加固前后试验拱的应变、挠度对比分析结果可看出:主拱经增设支撑加固增强处治后,强度、刚度明显提高,在同级荷载作用下,其应变值减少30%～40%.挠度值减少30%～50%,新增设的钢筋混凝土Y型支撑能与主拱协调变形、分担部分活载作用效应,提高了主拱的承载力.同时,增设的支撑对主拱裂缝的发展有抑制作用.该加固增强技术提高坦拱桥的承载能力的效果显著,可广泛应用于实践.     

矩形截面梁后张锚固区劈裂力计算的拉压杆模型法

针对矩形截面梁端部承受一个水平或倾斜锚固力的工况,根据主应力迹线构建出后张锚固区的拉压杆模型.在此基础上,利用拉压杆模型中节点力的平衡条件以及模型中的几何关系,推导出后张锚固区劈裂力大小的计算式.同时,利用有限元数值分析结果,拟合出劈裂应力合力重心位置的计算公式.在锚垫板宽度、锚固偏心距及力筋倾角变化的情况下,通过对比本文计算方法、美国AASHTO规范公式、欧洲FIP99建议公式的计算值以及有限元结果,表明所提出的劈裂力计算方法能够较好地反映锚垫板宽度、锚固偏心距以及力筋倾角对劈裂力大小以及劈裂应力合力重心位置的影响规律.与现有规范建议的计算公式相比,考虑的影响因素更为全面,计算精度更高.     

钢管混凝土系杆拱桥损伤吊索系统内力重分布研究

以某下承式钢管混凝土系杆拱桥为背景,建立该桥的三维有限元模型,采用有效横截面积减小率模拟吊索损伤,通过仿真计算分析单根吊索和多根吊索发生不同程度损伤时,吊索系统静拉力重分布规律.结果表明,损伤吊索系统的静拉力重分布只在损伤吊索与其两侧相邻吊索间进行,多根吊索损伤引起吊索系统静拉力重分布近似等效于各单根损伤吊索引起静拉力重分布的线性叠加.该结论对于系杆拱桥吊索系统力学分析与评估具有较大的工程实用价值.     

上海长江大桥主航道斜拉桥分离式钢箱梁设计

上海长江大桥主航道桥采用主跨730 m的双塔双索面斜拉桥,人字形塔,分离式钢箱梁.介绍分离式钢箱梁设计中纵横梁的连接及轨道交通的特殊构造两大特点、主要节点构造及主要计算内容.     

水泥混凝土梁桥沥青铺装结构设计方法探讨

以高速公路水泥混凝土梁桥沥青铺装层结构受力分析为基础,对复合桥面铺装结构设计方法进行了探讨,提出以沥青铺装层表面最大拉应力和最大剪应力分别作为结构设计的主要指标和辅助指标,同时对沥青混凝土桥面铺装结构设计方法及流程进行了总结,并进行了实例计算。     

A survey of wheel–rail contact models for rail vehicles

Accurate and efficient contact models for wheel–rail interaction are essential for the study of the dynamic behaviour of a railway vehicle. Assessment of the contact forces and moments, as well as contact geometry provide a fundamental foundation for such tasks as design of braking and traction control systems, prediction of wheel and rail wear, and evaluation of ride safety and comfort. This paper discusses the evolution and the current state of the theories for solving the wheel–rail contact problem for rolling stock. The well-known theories for modelling both normal contact (Hertzian and non-Hertzian) and tangential contact (Kalker's linear theory, FASTSIM, CONTACT, Polach's theory, etc.) are reviewed. The paper discusses the simplifying assumptions for developing these models and compares their functionality. The experimental studies for evaluation of contact models are also reviewed. This paper concludes with discussing open areas in contact mechanics that require further research for developing better models to represent the wheel–rail interaction.