公路货运通道梁式桥冲击系数研究

发布时间：2018-05-31 04:21

本文选题：梁式桥 + 公路货运通道　；参考：《北京交通大学》2014年硕士论文

【摘要】：桥梁是公路货运通道的重要组成部分,RC/PC简支梁桥和连续梁桥结构简单、施工方便,在桥梁中占有很大比例。由于车辆自身的振动以及路面不平顺等因素的存在,车辆过桥时会形成对桥梁的冲击。我国《公路桥涵设计通用规范》(JTGD60-2004)中冲击系数取值仅为桥梁基频的函数,而冲击系数与桥梁的动力特性、车辆振动特性及行驶状态、路面不平顺等都有很大的关系,冲击系数的合理取值及其适用范围是值得商榷的问题。公路货运通道车流量高、载重量大,本文针对公路货运通道的行车特点,对简支梁桥和连续梁桥的跨中位移冲击系数进行了计算分析。 1.在查阅国内外文献的基础上,对冲击系数的发展和研究现状进行了回顾和总结,对比了我国现行规范中冲击系数取值与其他国家规范值,各国冲击系数取值相差比较大,部分文献中的结果与我国现行规范冲击系数取值规律相反。 2.介绍了车桥相互作用模型的发展,建立三轴车辆的二维模型,用模态的方法建立桥梁模型,三角级数法生成路面的不平顺,推导了车桥相互作用方程,用Newmark-β法对方程进行求解。利用fortran语言编制了求解车桥相互作用方程的程序。通过与文献中计算结果的对比,验证本文程序的正确性。 3.以内蒙古某货运通道沿线桥梁为原型建立简支梁和连续梁桥的模型,模拟车辆匀速正常行驶、行车拥堵、在桥上制动和加速过桥4种行车状态,考虑梁型、车重、行车速度、行车时距、车辆数、路面不平顺等影响冲击系数的因素,利用正交试验的原理生成各种行车状态下的计算工况,用自编程序进行计算。分析各种行车状态下简支梁与连续梁跨中位移冲击系数随因素的变化趋势,以及冲击系数对各因素的敏感性。计算表明,不同行车状态下,冲击系数对各因素的敏感性不同,随各因素的变化趋势也不完全相同。对冲击系数影响最大的因素为路面不平顺,冲击系数随着路面不平顺等级的提高有较大幅度的增加。车辆匀速正常行驶时桥梁的冲击系数比拥堵和制动时略大,比加速过桥时小 4.考虑影响因素的不利水平,排列组合生成简支梁和连续梁冲击系数计算工况,根据计算结果拟合出了包含路面不平顺和桥梁基频两个参数的冲击系数计算公式。将拟合公式值与现行规范值进行对比分析,表明在路面不平顺等级较好时规范值偏大,计算值随着桥梁基频的增大有减小的趋势。 5.实测一座桥梁单车过桥时的冲击系数,对比实测值与本文拟合公式取值的大小。由于本文拟合公式是在多辆车及其他不利因素水平下拟合的,拟合公式取值偏于保守。
[Abstract]:The bridge is an important part of the highway freight corridor. The RC / PC simply supported beam bridge and the continuous beam bridge have simple structure and easy construction, and occupy a large proportion in the bridge. Because of the vibration of the vehicle itself and the existence of the road irregularity, the impact on the bridge will be formed when the vehicle crosses the bridge. In JTGD60-2004), the impact coefficient is only a function of the basic frequency of the bridge, and the impact coefficient has a great relationship with the dynamic characteristics of the bridge, the vibration characteristics and the driving state of the vehicle, the road surface irregularity and so on. The reasonable value of impact coefficient and its scope of application are debatable issues. Because of the high traffic flow and heavy load in the highway freight corridor, the displacement impact coefficient of the simply supported beam bridge and the continuous beam bridge is calculated and analyzed according to the driving characteristics of the highway freight corridor. 1. On the basis of consulting domestic and foreign literature, this paper reviews and summarizes the development and research status of impact coefficient, compares the value of impact coefficient between China's current code and other countries, and shows that the value of impact coefficient is quite different from that of other countries. Some of the results in the literature are contrary to the current norms in China. 2. The development of vehicle-bridge interaction model is introduced, the two-dimensional model of three-axis vehicle is established, the bridge model is built by modal method, the road surface irregularity is generated by triangle series method, the equation of vehicle-bridge interaction is deduced, and the equation is solved by Newmark- 尾 method. A program for solving the equations of vehicle-bridge interaction is developed by using fortran language. The correctness of the program is verified by comparing the results with the results in the literature. 3. Taking a bridge along a freight corridor in Inner Mongolia as a prototype, a model of a simple supported beam and a continuous beam bridge is built to simulate the normal running of the vehicle at a uniform speed, traffic congestion, braking on the bridge and accelerating the crossing of the bridge, taking into account the beam type, vehicle weight, driving speed. The factors affecting the impact coefficient, such as the running time distance, the number of vehicles, the road surface irregularity, etc., are calculated by using the principle of orthogonal test to generate the calculation conditions under various driving conditions. The variation trend of displacement impact coefficient of simply supported beam and continuous beam with factors and the sensitivity of impact coefficient to each factor are analyzed. The calculation results show that the sensitivity of impact coefficient to each factor is different and the trend is not identical with each factor under different driving conditions. The most influential factor on the impact coefficient is the road surface irregularity, and the impact coefficient increases greatly with the increase of the road surface irregularity grade. The impact coefficient of the bridge is a little larger than that of congestion and braking, and smaller than that of accelerating crossing the bridge. 4. Considering the unfavorable level of influencing factors, the calculation conditions of impact coefficient of simply supported beam and continuous beam are formed by arrangement and combination. According to the calculated results, the calculation formula of impact coefficient including two parameters of road surface irregularity and bridge foundation frequency is fitted. By comparing the fitting formula value with the current code value, it is shown that the value of the standard value is larger when the road surface irregularity grade is better, and the calculated value tends to decrease with the increase of the bridge foundation frequency. 5. The impact coefficient of a bridge over a single bridge is measured, and the magnitude of the measured value and the value of the fitting formula in this paper are compared. Because the fitting formula of this paper is fitted under the level of many vehicles and other unfavorable factors, the value of the fitting formula is conservative.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3

【参考文献】