宽钢箱梁精细化模型的车桥耦合振动分析

发布时间：2018-08-20 09:00

【摘要】：随着高强材料的使用,桥梁结构趋于柔性化；以及交通事业的快速发展,桥梁所承受的荷载越来越大。由于上述两方面原因决定了车辆荷载在桥梁总荷载中的比重日益增大,因此在车辆荷载作用下桥梁的动力响应日趋显著。活载作用下由箱梁横向的弯曲、剪切变形而产生不容忽视的箱梁横向挠曲。本文提出了一种精细化模型的分析方法进行车桥耦合分析,该方法使用壳单元建立桥梁主梁模型,进行车桥耦合动力分析。车桥耦合振动一般不会导致桥梁整体的毁坏,但是车辆过桥时,引起桥面的局部振动的大小和对桥面板的损坏程度尚无定论,但是在车辆荷载长期作用下,由于这样的局部振动会使桥面板出现疲劳、老化、开裂等问题。这些破损更易受到侵蚀,形成恶性循环。影响桥梁性能,增加养护费用。研究桥梁的局部振动问题将有助于人们更好地完善结构设计、规范车辆荷载并减少桥梁损坏。目前在分析车-桥耦合振动时,桥梁模型一般采用杆系单元建模,使用桥梁截面形心处的振动线性地描述桥面车轮处的振动。对于宽箱梁结构的桥梁,主梁截面横向除了体现主梁整体断面的振动以外,另外还包含了横向弯曲、剪切效应以及箱梁顶底板局部振动的影响。由于轮下桥面板的振动直接影响车-桥之间作用力的大小与方向,从而影响桥梁与车辆的振动性能评价,因此,对于宽箱梁桥梁有必要建立精细化的模型对车-桥耦合振动影响的方式及水平开展具体研究,并对此类桥梁的杆系模型适应性和现行桥梁规范冲击系数计算作出评价。本文在总结已有的车-桥耦合振动研究成果基础上,编制了空间薄壳单元有限元计算程序,在课题组自主车-桥耦合振动分析软件IPSAA中进行分析,具体完成以下工作： ①基于Mindlin板单元理论,采用等参变换思想,将板单元的弯曲效应和平面应力效应叠加,选择对剪切刚度项采取低阶积分的方法来克服板的剪切闭锁问题,编制任意四边形四结点壳单元有限元程序(ShellM4),并使用Ansys来验证编制的壳单元的力学性能。 ②基于Kirchhoff板单元理论,同样将板单元的弯曲效应和平面应力效应叠加,编制任意三角形壳单元的有限元程序,而一个任意四边形被它的形心点划分为4个三角形,采用静力凝聚的方法,凝聚掉四边形的形心点的自由度,即可得到一个由三角形构成的任意四边形壳单元(ShellF4),使用Ansys验证其力学性能。 ③基于龙驭球提出的基于四边形面积坐标的广义协调壳单元理论编制了厚薄通用壳单元(Shell4GA),验证该壳单元的力学性能。 ④将理论应用于实践,针对某三跨连续钢箱梁桥开展了精细化车桥耦合振动分析,并与杆系桥梁模型的动力响应进行对比,研究了不同车道行车的动力响应、挠度时程的频谱分析以及冲击系数的差异,研究表明：1)精细化模型的车桥耦合分析中,由于高频参与了振型,增强了桥面板的局部振动,导致精细化模型的车桥耦合振动分析计算结果大于杆系模型的计算值,精细化模型更加符合实际情况,2)精细化模型计算得到的冲击系数大于规范的取值,有利于规范桥梁的设计、施工和养护。
[Abstract]:With the use of high-strength materials, the bridge structure tends to be flexible; as well as the rapid development of transportation, the load on the bridge is becoming larger and larger. Because of the above two reasons, the proportion of vehicle load in the total load of the bridge is increasing day by day, so the dynamic response of the bridge under vehicle load is becoming more and more significant. Lateral deflection of box girder can not be neglected due to transverse bending and shearing deformation of box girder. In this paper, a refined model analysis method is proposed for vehicle-bridge coupling analysis.
Vehicle-bridge coupling vibration generally does not lead to the destruction of the whole bridge, but the magnitude of local vibration and the damage degree of bridge deck are still uncertain when vehicles cross the bridge. However, under the long-term load of vehicles, such local vibration will cause fatigue, aging and cracking of bridge deck. Corrosion will lead to a vicious cycle, which will affect the performance of the bridge and increase the maintenance cost. The study of the local vibration of the bridge will help people to better improve the structural design, standardize the vehicle load and reduce the damage of the bridge.
At present, in the analysis of vehicle-bridge coupling vibration, the bridge model is generally modeled by the rod system element, and the vibration at the center of the bridge section is used to describe the vibration at the wheel of the deck linearly. Because the vibration of the bridge deck under the wheel directly affects the magnitude and direction of the force between the vehicle and the bridge, and thus affects the vibration performance evaluation of the bridge and the vehicle, it is necessary to establish a refined model for the wide box girder bridge to study the mode and level of the influence of the coupling vibration between the vehicle and the bridge. The adaptability of the bridge model and the calculation of impact coefficient of existing bridge specifications are also evaluated.
On the basis of summarizing the existing research results of vehicle-bridge coupling vibration, this paper compiles the finite element calculation program of space thin shell element, and carries on the analysis in the independent vehicle-bridge coupling vibration analysis software IPSAA of the research group. The concrete work is as follows:
(1) Based on Mindlin plate element theory, the bending effect and plane stress effect of plate element are superimposed by isoparametric transformation, and the shear locking problem of plate is overcome by low-order integral of shear stiffness term. The finite element program of arbitrary quadrilateral four-node shell element (ShellM4) is compiled and verified by Ansys. The mechanical properties of the element.
(2) Based on Kirchhoff's plate element theory, the bending effect and plane stress effect of the plate element are also superimposed, and the finite element program of arbitrary triangular shell element is compiled. An arbitrary quadrilateral is divided into four triangles by its center point, and the degree of freedom of the center point of the quadrilateral is condensed by means of static condensation. An arbitrary quadrilateral shell element (ShellF4) consisting of a triangle is used to verify its mechanical properties using Ansys.
(3) Based on the theory of generalized conforming shell element based on quadrilateral area coordinates proposed by Longyu Ball, a thick and thin universal shell element (Shell 4GA) was developed to verify the mechanical properties of the shell element.
(4) The theory is applied to practice, and the refined coupled vibration analysis of a three-span continuous steel box girder bridge is carried out, and the dynamic response of the bridge model is compared with that of the link bridge model. The dynamic response, the spectrum analysis of deflection time history and the difference of impact coefficient of different lanes are studied. In the combined analysis, the high frequency participates in the vibration mode and enhances the local vibration of the bridge deck, which results in the calculation result of the vehicle-bridge coupling vibration of the refined model is larger than that of the rod model, and the refined model is more in line with the actual situation. 2) The impact coefficient calculated by the refined model is larger than the normative value, which is conducive to the standardization of the bridge design. Plan, construction and maintenance.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441.3

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