山区风环境数值模拟与基于虚拟激励法的拱桥抖振响应分析

发布时间：2018-06-26 02:44

本文选题：大跨度拱桥 + 数值风洞　；参考：《西南交通大学》2017年硕士论文

【摘要】：我国西部地区地形特点为多山地,为了满足西部地区经济发展的需求,近年来很多修建在山区的桥梁应运而生,随着桥梁跨度的不断提高,山区桥梁风致振动问题也愈加凸显,因而山区复杂地形风环境的准确描述至关重要。由于气象资料的缺乏以及山区复杂的地形特征,设计风参数很难通过规范确定,因此有必要对山区风环境进行三维数值模拟。在风致振动研究中,抖振分析是进行桥梁抗风安全性评估的重要环节,过大的抖振响应将会影响到桥梁运营阶段行车的安全性和舒适性。虚拟激励法作为一种高效精确的求解结构随机振动响应的频域方法,易于编程实现,在抖振分析领域有较为广泛的应用。本文以一座西部山区的大跨度拱桥为研究背景,利用CFD数值风洞技术对桥址区风参数进行三维地形数值模拟计算,结合风参数模拟结果,基于虚拟激励法利用有限元软件对桥梁进行抖振响应分析。首先,回顾了国内外拱桥的发展历程,并对山区风环境数值模拟和桥梁抖振响应研究的现状进行了阐述,综述了两种研究的试验方法和数值模拟方法,并简述了大气边界层风特性以及风荷载计算的相关理论。然后,利用CFD进行了桥址区风参数数值模拟。按照圆曲线+余弦曲线的形式对桥址区边界进行拓展,在边界上利用自编UDF函数施加入口风速剖面和湍流强度剖面,在FLUENT中选用SSTk-ω模型对流场进行求解,提取并讨论了风参数模拟计算的结果。最后,将虚拟激励法理论与桥梁抖振响应理论相结合,推导了多维多点抖振响应计算的虚拟激励法计算公式,并利用有限元软件进行实现。建立桥梁有限元模型,结合节段模型静力三分力风洞试验结果,构造虚拟激励荷载矢量,对该桥成桥状态和施工最不利状态进行抖振响应计算,提取响应结果。通过对不同结构状态、不同风速取值桥梁抖振响应结果的对比分析,得到一些对工程实践有参考意义的结论。
[Abstract]:In order to meet the needs of economic development in western China, many bridges built in mountainous areas have emerged as the times require in recent years. With the continuous improvement of bridge span, wind-induced vibration of bridges in mountainous areas has become increasingly prominent. Therefore, it is very important to accurately describe the wind environment of complex terrain in mountain area. Due to the lack of meteorological data and the complex terrain characteristics of mountainous areas, it is difficult to determine the design wind parameters through the specification, so it is necessary to carry out three-dimensional numerical simulation of the wind environment in mountainous areas. In the study of wind-induced vibration buffeting analysis is an important part of bridge anti-wind safety evaluation. Excessive buffeting response will affect the safety and comfort of the bridge operation phase. As an efficient and accurate frequency-domain method to solve the random vibration response of structures, the virtual excitation method is easy to be programmed and widely used in buffeting analysis. In this paper, a large span arch bridge in the western mountainous area is used as the research background. Using CFD numerical wind tunnel technique, the wind parameters of the bridge site are simulated and calculated by 3D terrain numerical simulation, and the results of wind parameter simulation are combined. Based on virtual excitation method, the buffeting response of bridge is analyzed by finite element software. Firstly, the development history of arch bridges at home and abroad is reviewed, and the current situation of wind environment numerical simulation and bridge buffeting response in mountainous areas are described. The two experimental methods and numerical simulation methods are summarized. The wind characteristics of the atmospheric boundary layer and the theory of wind load calculation are briefly described. Then, CFD is used to simulate the wind parameters of the bridge site. The boundary of bridge site is extended according to the form of circular curve cosine curve. The inlet wind velocity profile and turbulence intensity section are applied on the boundary by using the self-made UDF function, and the SSTk- 蠅 model is chosen to solve the flow field in fluent. The simulation results of wind parameters are extracted and discussed. Finally, combining the theory of virtual excitation method with the theory of buffeting response of bridge, the formula of virtual excitation method for calculating multi-dimensional and multi-point buffeting response is derived, and realized by finite element software. The finite element model of the bridge is established. The virtual excitation load vector is constructed based on the static three-point wind tunnel test results of the segmental model. The buffeting response of the bridge is calculated and the response results are extracted. By comparing and analyzing the buffeting response results of bridges with different structural states and different wind speeds, some useful conclusions are obtained for engineering practice.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441.3

【参考文献】