波浪力作用下的桥梁抗震研究
发布时间：2018-11-29 08:29
【摘要】：随着经济的发展与技术的进步,桥梁的跨越能力逐渐增强,大跨桥梁如雨后春笋般涌现在全国各地。这些跨越宽阔水域的大跨桥梁所处在的水域水深也往往较深。深水大跨桥梁所处水域水面宽广,风浪较大,波浪荷载是重要的荷载之一。地震特别是强震给深水大跨桥梁的安全带来了极大的威胁。而且在地震时,大地运动造成水体底部或者岸边的运动还会引起强烈的水体运动,蕴含了巨大的能量,此时桥梁结构承受着波浪与地震的共同作用,而现有的抗震设计往往忽略水体作用单独考虑结构在无水状态的抗震性能,或者只考虑地震引起的结构与水体的耦合振动而忽略在波浪力的影响,所以有必要研究桥梁结构在波浪力作用下的抗震性能。本文从整体上研究了桥梁结构在波浪力作用下的地震反应。其主体包含:研究背景与现状,水体与结构共同作用体系理论,地震动水压力常用计算方法、三维数值波浪水槽模拟,波浪力作用下桥梁结构的地震反应等。具体研究内容如下:①简要介绍了我国公路规范与铁路规范中对地震动水压力的相关规定及计算公式;推导了莫里森方程,并将其线性化。莫里森方程是目前工程实践中广泛使用的经验公式。逐渐也被应用在动水压力的计算分析中,是一个非常常见的计算方法。全面的介绍了辐射波浪理论,包括其流体控制方程、边界条件以及求解动水压力的过程。②介绍了线性波浪理论及二阶Stokes波浪理论的基本公式,不同的波浪理论在使用边界造波法造波时边界上的波浪参数有不同的输入值;介绍边界造波法的原理、波浪运动的控制方程及自由表面追踪的VOF方法,为三维波浪数值模拟提供理论依据;建立三维数值波浪水槽,利用边界造波法,依据不同的波浪理论给定入口边界速度及波高等波浪参数,通过CFD软件得到了三维的数值波浪。③利用三维数值波浪水槽,对一个基于实际工程的连续刚构桥数值模型施加波浪力,进而考察在波浪力作用下桥梁结构的动力响应。波浪力的存在改变了结构的自振频率,各阶自振频率均有不同程度的减小。这说明波浪力会改变结构的动力特性。波浪力的存在改变了结构的动力反应,不同程度的增大了结构的动力反应,其改变较大不可忽略。说明在分析桥梁结构的地震反应时应当考虑到波浪力的影响。同时计入波浪与地震的影响时,因为两者在单独作用时的动力反应峰值并非在同一时间,所以在同时计入两者影响时结构的动力反应峰值并非是两者单独作用时动力反应之和。
[Abstract]:With the development of economy and the progress of technology, the span ability of bridges is gradually strengthened, and long span bridges sprang up all over the country. These long-span bridges across wide waters also tend to have deeper water depths. The deep water area of long span bridge is wide, the wind wave is large, wave load is one of the important loads. Earthquakes, especially strong earthquakes, pose a great threat to the safety of long span bridges in deep water. And during the earthquake, the earth movement causes the motion of the bottom or shore of the water body to cause the strong motion of the water body, which contains enormous energy. At this time, the bridge structure is subjected to the interaction of wave and earthquake. However, the existing seismic design often neglects the effect of water body to consider the seismic behavior of the structure in anhydrous state alone, or only considers the coupling vibration of the structure and the water body caused by earthquake, and neglects the influence of the wave force. So it is necessary to study the seismic behavior of bridge structure under the action of wave force. The seismic response of bridge structure under wave force is studied in this paper. Its main body includes: research background and present situation, water body and structure interaction system theory, commonly used calculation method of ground motion water pressure, three-dimensional numerical wave flume simulation, seismic response of bridge structure under wave force, etc. The main contents of this paper are as follows: 1 the relevant provisions and calculation formulas of the ground motion water pressure in the highway code and the railway code in China are briefly introduced, and the Morrison equation is deduced and linearized. Morrison equation is a widely used empirical formula in engineering practice. It is a very common method to calculate the hydrodynamic pressure. The radiation wave theory, including its governing equation, boundary conditions and the process of solving the hydrodynamic pressure, is introduced. 2 the basic formulas of linear wave theory and second-order Stokes wave theory are introduced. Different wave theories have different input values of wave parameters on the boundary when using the boundary wave-making method. This paper introduces the principle of the boundary wave-making method, the governing equation of wave motion and the VOF method of free surface tracing, which provides a theoretical basis for 3-D wave numerical simulation. Three-dimensional numerical wave flume was established, and the inlet boundary velocity and wave parameters were given according to different wave theory. The three-dimensional numerical wave was obtained by CFD software. The wave force is applied to a numerical model of a continuous rigid frame bridge based on practical engineering, and the dynamic response of the bridge structure under the action of wave force is investigated. The natural frequency of the structure is changed by the wave force, and the natural frequency of each order decreases to some extent. This shows that the wave force will change the dynamic characteristics of the structure. The existence of wave force changes the dynamic response of the structure, and increases the dynamic response of the structure to varying degrees, which can not be ignored. It is suggested that the influence of wave force should be taken into account in the analysis of seismic response of bridge structure. Considering the influence of wave and earthquake, the peak value of dynamic response of the structure is not the sum of the dynamic response of the structure when the two effects are taken into account at the same time, because the peak value of the dynamic response of the two forces is not at the same time.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55
本文编号：2364503
[Abstract]:With the development of economy and the progress of technology, the span ability of bridges is gradually strengthened, and long span bridges sprang up all over the country. These long-span bridges across wide waters also tend to have deeper water depths. The deep water area of long span bridge is wide, the wind wave is large, wave load is one of the important loads. Earthquakes, especially strong earthquakes, pose a great threat to the safety of long span bridges in deep water. And during the earthquake, the earth movement causes the motion of the bottom or shore of the water body to cause the strong motion of the water body, which contains enormous energy. At this time, the bridge structure is subjected to the interaction of wave and earthquake. However, the existing seismic design often neglects the effect of water body to consider the seismic behavior of the structure in anhydrous state alone, or only considers the coupling vibration of the structure and the water body caused by earthquake, and neglects the influence of the wave force. So it is necessary to study the seismic behavior of bridge structure under the action of wave force. The seismic response of bridge structure under wave force is studied in this paper. Its main body includes: research background and present situation, water body and structure interaction system theory, commonly used calculation method of ground motion water pressure, three-dimensional numerical wave flume simulation, seismic response of bridge structure under wave force, etc. The main contents of this paper are as follows: 1 the relevant provisions and calculation formulas of the ground motion water pressure in the highway code and the railway code in China are briefly introduced, and the Morrison equation is deduced and linearized. Morrison equation is a widely used empirical formula in engineering practice. It is a very common method to calculate the hydrodynamic pressure. The radiation wave theory, including its governing equation, boundary conditions and the process of solving the hydrodynamic pressure, is introduced. 2 the basic formulas of linear wave theory and second-order Stokes wave theory are introduced. Different wave theories have different input values of wave parameters on the boundary when using the boundary wave-making method. This paper introduces the principle of the boundary wave-making method, the governing equation of wave motion and the VOF method of free surface tracing, which provides a theoretical basis for 3-D wave numerical simulation. Three-dimensional numerical wave flume was established, and the inlet boundary velocity and wave parameters were given according to different wave theory. The three-dimensional numerical wave was obtained by CFD software. The wave force is applied to a numerical model of a continuous rigid frame bridge based on practical engineering, and the dynamic response of the bridge structure under the action of wave force is investigated. The natural frequency of the structure is changed by the wave force, and the natural frequency of each order decreases to some extent. This shows that the wave force will change the dynamic characteristics of the structure. The existence of wave force changes the dynamic response of the structure, and increases the dynamic response of the structure to varying degrees, which can not be ignored. It is suggested that the influence of wave force should be taken into account in the analysis of seismic response of bridge structure. Considering the influence of wave and earthquake, the peak value of dynamic response of the structure is not the sum of the dynamic response of the structure when the two effects are taken into account at the same time, because the peak value of the dynamic response of the two forces is not at the same time.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55
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