汽车制动作用下梁桥的动力响应及冲击系数的研究

发布时间：2018-03-12 13:55

本文选题：汽车制动　切入点：三维车桥模型　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：车辆荷载是桥梁结构所要求承担的重要荷载之一,是桥梁设计中需要考虑的重要因素。在车桥系统动力分析中,将车辆假定为在桥上匀速运动的研究已经比较成熟;各国桥梁设计规范也一般是基于汽车匀速行驶情况计算冲击系数。然而实际交通状况下,车辆在桥上遇突发状况不可避免会作紧急刹车等非匀速运动,导致桥梁的动力响应明显大于匀速行驶情况,产生的冲击系数可能会超过规范值。因此在车桥耦合振动的研究中考虑汽车制动的影响是很有必要的。本文应用三维有限元车桥模型研究了汽车制动作用下不同跨径与截面形式的梁桥的动力响应及冲击系数,主要内容有:(1)首先基于汽车匀速条件下的车桥耦合程序提出了考虑汽车变速运动的方法,通过车辆接触力的变化规律验证了该方法的正确性;接着选取一辆两轴汽车模型和美国规范中一座经典的简支预应力混凝土梁桥进行研究,获得了该桥的跨中动力响应及冲击系数,对影响冲击系数的几个重要参数进行了研究,并简单对比了汽车加速和减速结果的异同。(2)应用该车桥耦合振动程序,计算了五座不同跨径的简支预应力混凝土T梁桥在一辆典型重车(HS20-44)制动作用下的位移、应变和剪力冲击系数,考察了它们在不同工况下的异同,并且与美国规范和我国规范值进行了对比,发现汽车制动作用下的冲击系数有超过规范值的现象。(3)计算了包括简支和连续梁桥在内的六座不同截面和跨径的混凝土梁桥在三轴重车HS20-44制动下的冲击系数,分别研究了刹车位置、减速度、速度、路面平整度等几个重要因素对冲击系数的影响规律,对不同截面类型梁桥的冲击系数结果进行了比较,并将计算的冲击系数值与我国规范值进行了对比。
[Abstract]:Vehicle load is one of the important loads required by bridge structure and an important factor to be considered in bridge design. The design codes of bridges all over the world generally calculate the impact coefficient based on the constant speed driving of the vehicle. However, under the actual traffic condition, it is inevitable for the vehicle to make non-uniform motion such as emergency brake in the bridge when the vehicle is in a sudden situation. As a result, the dynamic response of the bridge is obviously larger than that of the uniform speed. Therefore, it is necessary to consider the influence of vehicle braking in the study of vehicle-bridge coupling vibration. In this paper, the three-dimensional finite element model is used to study the different effects of vehicle braking. The dynamic response and impact coefficient of beam bridges with span and cross section, Firstly, based on the vehicle-bridge coupling program under the condition of uniform vehicle speed, the method of considering the variable speed motion of the vehicle is put forward, and the correctness of the method is verified by the law of vehicle contact force. Then, a two-axle vehicle model and a classic simply supported prestressed concrete beam bridge in American Code are selected to study the dynamic response and impact coefficient of the bridge, and several important parameters affecting the impact coefficient are studied. The difference and similarities of acceleration and deceleration results of the vehicle are compared. (2) the displacement of five simply supported prestressed concrete T-beam bridges with different spans under the braking action of a typical heavy truck HS20-44) is calculated by using the coupled vibration program of the vehicle and bridge. The strain and shear impact coefficients are investigated, and the differences and similarities between them under different working conditions are investigated and compared with the values of the American Code and the Chinese Code. It is found that the impact coefficient of six concrete beam bridges with different cross-sections and spans under triaxial load truck HS20-44 braking is calculated by using the phenomenon that the impact coefficient of automobile brake is above the standard value. (3) the impact coefficient of six concrete beam bridges with different cross-sections and spans, including simply supported and continuous beam bridges, is calculated. The effects of braking position, deceleration, speed and pavement smoothness on impact coefficient are studied, and the results of impact coefficient of different cross-section girder bridges are compared. The calculated values of impact coefficient are compared with the values of China Code.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3

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