大跨度斜拉桥风压分布特性的数值模拟研究

发布时间：2018-11-16 20:05

【摘要】：风灾是全球最常见和最严重的自然灾害之一,其不仅频繁地损坏大量的工程结构,也给人类的社会活动和日常生活造成了严重影响,从而导致人类社会巨大的生命和财产损失。尤其对于桥梁结构而言,因风作用下的桥梁结构发生严重的风毁事故屡见不鲜。当前,全球范围内大量跨海连岛工程正在规划建设中,其标志着世界桥梁工程又一次进入了新时期。然而跨越沿海海湾、海峡的特大跨径桥梁在我国规划建设的桥梁中也占有很大一部分。因此,桥梁跨度的不断加大,导致结构越来越轻柔,越来越容易发生振动,尤其是由风作用引发的结构振动。风荷载成为影响桥梁结构安全的最重要控制因素之一,人们对于风作用下的桥梁安全性问题极为关注,大跨度斜拉桥的抗风亦然成为桥梁专家及学者们所需要解决的首要问题。本文在交通部西部课题及湖南省自然基金的支持下,以岳阳洞庭湖大桥为研究背景,通过现场实测和数值模拟技术(CFD)相结合的研究方法对大桥风场特性、大桥桥塔(主塔)及主梁跨中断面在风载作用下的风压分布以及气动参数等进行研究和分析,从而为此类的大跨度桥梁结构的抗风设计提供一定的参考。本文的主要工作内容如下:1.利用Matlab数值分析软件对大桥桥位处塔顶及桥面同步采集的风速数据进行统计分析,得到风荷载计算所需要的平均风速剖面,?指数拟合、紊流强度及阵风因子,以此来推断大桥桥位处地表所属的粗糙度类别。2.对桥塔进行传压管的铺设、风压数据的采集和处理,通过FLUENT前处理器Gambit建立与桥塔实际尺寸相当的三维几何模型,对桥塔进行三维绕流的数值模拟分析,将数值模拟结果与实测结果进行比较,验证本文数值模拟方法的可靠性与可行性。在此基础上对桥塔进行不同风速风向下的五分力系数以及桥塔塔柱间的流场干扰效应进行数值模拟,获得了不同风速风向下的桥塔五分力系数的变化规律和其塔柱周围风压、流场矢量图,并对结果进行研究和分析。3.根据已有的实测桥梁断面三分力系数,通过FLUENNT前处理器Gambit建立与主梁断面实际尺寸相当的二维几何模型,在均匀流条件下,对主梁断面进行二维绕流的数值模拟分析,将数值模拟计算得到的三分力系数和实测结果作比较,从而验证本文数值模拟方法的可靠性与可行性。在此基础上对主梁断面进行不同风攻角下的三分力系数进行数值模拟,获得了不同风速风向下的主梁断面三分力系数的变化规律和其周围的风压、流场矢量图,并对结果进行研究和分析。
[Abstract]:Wind disaster is one of the most common and serious natural disasters in the world. It not only frequently damages a large number of engineering structures, but also seriously affects human social activities and daily life, resulting in huge loss of life and property in human society. Especially for bridge structure, serious wind damage accidents occur frequently due to wind action. At present, a large number of sea-crossing and island-crossing projects are under planning and construction all over the world, which marks a new era for the bridge engineering in the world. However, large span bridges across the coastal gulf and straits also account for a large part of the bridges planned and constructed in China. Therefore, with the increasing span of bridges, the structure becomes more and more gentle and more prone to vibration, especially the vibration caused by wind. Wind load has become one of the most important control factors affecting the safety of bridge structure. People pay great attention to the safety of bridge under the action of wind, and the wind-resistance of long-span cable-stayed bridge has become the most important problem that bridge experts and scholars need to solve. In this paper, based on the research background of Yueyang Dongting Lake Bridge, the wind-field characteristics of Yueyang Dongting Lake Bridge are studied by the combination of field measurement and numerical simulation technology (CFD), with the support of the Western Project of Ministry of Communications and the Hunan Province Natural Fund. The wind pressure distribution and aerodynamic parameters of the bridge tower (main tower) and the midspan section of the main girder under the action of wind load are studied and analyzed so as to provide a certain reference for the wind-resistant design of this kind of long-span bridge structure. The main work of this paper is as follows: 1. Using Matlab numerical analysis software, the wind speed data collected synchronously from the tower top and the bridge deck at the bridge location are statistically analyzed, and the average wind speed profile required for wind load calculation is obtained. Exponential fitting, turbulence intensity and gust factor are used to infer the roughness category at bridge site. 2. 2. The bridge tower is laid, the data of wind pressure is collected and processed, and the three-dimensional geometric model is established by Gambit, which is equivalent to the actual size of the tower, and the numerical simulation of the flow around the tower is carried out. The reliability and feasibility of the numerical simulation method are verified by comparing the numerical simulation results with the measured results. On this basis, the five-point force coefficient under different wind speed and wind direction and the interference effect of flow field between tower columns are numerically simulated. The variation law of five-point force coefficient under different wind speed and wind direction and the wind pressure around the tower column are obtained. Flow field vector diagram, and research and analysis of the results. 3. According to the existing measured three-point force coefficients of the bridge section, a two-dimensional geometric model equivalent to the actual size of the main beam section is established by Gambit, a pre-processor of FLUENNT. Under the condition of uniform flow, the two-dimensional flow around the main beam section is numerically simulated and analyzed. By comparing the calculated results with the measured results, the reliability and feasibility of the numerical simulation method in this paper are verified. On the basis of this, the three-point force coefficient of the main beam section under different wind attack angles is numerically simulated, and the variation law of the three-point force coefficient of the main beam section under different wind speed and wind direction is obtained, and the wind pressure and flow field vector diagram around the main girder section are obtained. The results were studied and analyzed.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.27

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