中小跨径梁桥动力冲击系数研究

发布时间：2018-05-08 06:59

本文选题：车桥耦合振动 + 动力冲击系数　；参考：《湖南大学》2015年硕士论文

【摘要】：中小跨径梁桥构造简单、受力明确,具有设计和施工高度标准化的特点,是世界上应用最为广泛的桥型。截至2010年底,我国公路桥梁已经超过65万座,中小跨径梁桥占据了其中绝大部分。然而近几十年来公路运输需求迅速扩大,车辆荷载、数量和车速均不断提高,桥梁失效事件时有发生,使得明确中小跨径梁桥在移动车辆荷载作用下的动力荷载效应、获得准确的桥梁动力冲击系数(IM)以用于评估既有桥梁承载力和合理指导新桥设计,成为桥梁领域亟待解决的重要问题。世界各国(包括我国)学者已经指出桥梁设计规范中使用的冲击系数可能低估了桥梁的实际动力响应。且目前关于桥梁支承方式、桥梁截面类型、桥梁受力构件材料、车辆荷载等级等因素对IM的影响的研究不够深入。规范计算IM时,对这些重要影响因素也并未加以考虑。本文建立了基于车桥耦合振动理论的IM研究方法,对中小跨径梁桥在车辆荷载作用下的IM进行了研究,深入探讨了IM受截面形式、支承方式、路面等级、桥梁跨径、行车速度等因素影响的规律,获得了一些有意义的结论。这些成果可做为规范的补充为桥梁研究人员和工程师所参考。主要内容如下:(1)推导和建立了车辆、桥梁的有限元模型和车桥耦合振动动力学方程,结合模态叠加法,推导了逐步迭代求解的数值算法,给出了编制电算程序的流程。(2)通过数值模拟方法计算了多种不同类型中小跨径梁桥在复杂行驶工况下的IM,用计算结果对中美桥梁设计规范进行了检验,指出了我国89规范、04规范设计值可能低估了车辆行驶时桥梁的实际IM。(3)计算了常见不同截面类型梁桥的IM。对路面平整度、车辆类型、行车速度等重要因素进行了参数分析,指出不同截面类型桥梁的IM具有较大的离散性,其差异应引起工程人员的注意。(4)建立了混凝土简支桥梁、连续梁桥及钢主梁—混凝土面板桥梁模型,分别探讨了连续梁桥IM和简支梁桥IM、弯矩IM和剪力IM的差异。发现现行规范对桥梁支承方式、桥梁上部结构材料引起的IM差异的考虑不足,将现行规范应用于连续梁桥和组合梁桥可能并不十分合理。
[Abstract]:Small and medium span girder bridge is the most widely used bridge type in the world because of its simple structure, clear force and high standardization in design and construction. Up to the end of 2010, there are more than 650000 highway bridges in China, most of which are small and medium span girder bridges. However, in recent decades, the demand for highway transportation has expanded rapidly, the vehicle load, quantity and speed have been increasing continuously, and the bridge failure events have occurred from time to time, which makes clear the dynamic load effect of small and medium-sized span beam bridge under moving vehicle load. Obtaining accurate dynamic impact coefficient (IMC) of bridges to evaluate the bearing capacity of existing bridges and reasonably guide the design of new bridges has become an important problem to be solved urgently in the field of bridges. Scholars from all over the world (including China) have pointed out that the impact coefficient used in the bridge design code may underestimate the actual dynamic response of the bridge. At present, the research on the influence of bridge supporting mode, bridge section type, bridge bearing material, vehicle load grade and other factors on IM is not deep enough. These important factors are not taken into account when calculating IM. In this paper, an IM research method based on vehicle-bridge coupling vibration theory is established, and the IM of medium and small span beam bridge under vehicle load is studied, and the form of section, supporting mode, pavement grade, span of bridge are deeply discussed. Some meaningful conclusions are obtained on the influence of driving speed and other factors. These results can be used as a reference for bridge researchers and engineers. The main contents are as follows: (1) the finite element model of vehicle and bridge and the dynamic equation of vehicle-bridge coupling vibration are derived and established. Combined with the modal superposition method, the numerical algorithm of step by step iterative solution is derived. The flow chart of compiling computer program is given. (2) through numerical simulation method, the IMMOs of many different types of small and medium span girder bridges under complex driving conditions are calculated, and the design codes of bridges in China and America are tested with the results of calculation. It is pointed out that the design value of the code YI04 of 89 code of our country may underestimate the actual IM.3 of the bridge when the vehicle is running) and calculate the IMs of the common beam bridges of different cross-section types. This paper analyzes the important factors such as pavement smoothness, vehicle type, driving speed and so on, and points out that the IM of different cross-section bridges has greater discreteness, the difference of which should attract the attention of engineers. The model of continuous beam bridge and steel main beam-concrete slab bridge is discussed, and the difference of IM, moment IM and shear IM of continuous beam bridge and simply supported beam bridge is discussed respectively. It is found that the current code does not consider the bridge support mode and the IM difference caused by the bridge superstructure material, and it may not be very reasonable to apply the current code to continuous beam bridges and composite beam bridges.
【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

【参考文献】