山地城市钢桥杆件风致振动研究

发布时间：2018-03-18 19:06

本文选题：风致振动　切入点：山地城市　出处：《重庆交通大学》2016年硕士论文　论文类型：学位论文

【摘要】：我国是多山的国家,山地城市中的桥梁因其复杂的地形地貌环境,在抗风设计要求上不同于平原城市,这不仅涉及到山地城市风场特性、桥梁结构本身特性,更要考虑二者的共同作用。山地城市风场特性与平原城市差别很大,现有规范对山地城市风场风特性描述极少。因此,为了有效控制钢拱桥杆件的多种有害风振、延长桥梁使用寿命、保证整体桥梁的安全和确保山地城市中的交通安全通行,对山地城市钢拱桥杆件风振机理的研究是非常有必要的,且具有十分重要的理论价值和实际意义。现代桥梁的发展,因要求需要促使其向着跨度大,结构柔和质量轻的方向发展,这使得结构对风荷载的作用显得更加敏感。大跨度钢桥中的杆件是风敏感结构,在一定风速作用下,极易引发涡激振动。本文依托重庆朝天门大桥,取其典型杆件作为研究对象,利用ANSYS-FLUENT软件,通过将四阶Runge-Kutta法以自编UDF程序形式嵌入其中的方法对典型杆件的涡激振动数值模拟,主要工作有以下几方面:(1)对二维模型在非定常流场中数值模拟,将所得的升力系数、阻力系数、频率、Strouhal数等参数同已有试验值及数值模拟值比对,验证静态流场数值模拟的准确性。(2)对比Realizable k-ε和SST k-ω两类模型的三分力系数的平均值及标准差,分析两类模型的变化规律,比较模型的精准性;同时,对比不同风攻角下的三分力系数,对不同风攻角升力系数和阻力系数变化规律总结,并分析了不同风速下的涡激振动锁定区间及升力系数和阻力系数变化规律。(3)利用ANSYS-FLUENT软件的二次开发,自编UDF程序,模拟二维方柱在动态流场中数值模拟,获取位移时程曲线以及风速锁定区变化情况,分析了三分力系数变化规律和动态流场中流固耦合的拍动现象。(4)将全隐式四阶Runge-Kutta法以自编UDF程序形式嵌入到ANSYS-FLUENT中,对朝天门大桥典型杆件进行涡激振动仿真模拟,选取风速、风攻角及阻尼比三个影响因素比较分析,分别分析了涡振锁定风速区间,最不利风攻角以及阻尼比对涡激振动的影响。在进行桥梁设计时,要尽量避开发生涡致振动时的风速、阻尼和风攻角,避免发生共振和加速结构的破坏速度。
[Abstract]:China is a mountainous country. Because of its complex terrain and landform environment, bridges in mountainous cities are different from those in plain cities in wind-resistant design, which involves not only the characteristics of wind field in mountainous cities, but also the characteristics of bridge structure itself. The characteristics of wind field in mountainous cities are very different from those in plain cities, and the existing codes seldom describe the wind characteristics of mountain cities. Therefore, in order to effectively control the harmful wind-induced vibration of steel arch bridge members, It is necessary to study the wind-induced vibration mechanism of steel arch bridge in mountainous cities, which can prolong the service life of bridges, ensure the safety of the whole bridge and ensure the traffic safety in mountainous cities. The development of modern bridges is required to develop towards the direction of long span, soft structure and light mass. This makes the structure more sensitive to the action of wind load. The members of long-span steel bridge are wind sensitive structures, which are apt to cause vortex-induced vibration under certain wind speed. This paper relies on the Chaotianmen Bridge in Chongqing. Taking the typical member as the research object, using the ANSYS-FLUENT software, the numerical simulation of the vortex-induced vibration of the typical member is carried out by embedding the fourth-order Runge-Kutta method in the form of self-compiled UDF program. The main work is as follows: 1) numerical simulation of the two-dimensional model in unsteady flow field. The obtained parameters such as lift coefficient, drag coefficient, frequency and Strouhal number are compared with existing experimental values and numerical simulation values. Verify the accuracy of static flow field numerical simulation.) compare the mean value and standard deviation of Realizable k- 蔚 model and SST k- 蠅 model, analyze the variation law of the two models, compare the accuracy of the model, at the same time, Compared with the three-point force coefficient under different wind attack angle, summarized the variation law of lift coefficient and resistance coefficient of different wind attack angle. The variation of lift coefficient and drag coefficient under different wind speed is analyzed. Using the secondary development of ANSYS-FLUENT software, a UDF program is developed to simulate the numerical simulation of two-dimensional square column in the dynamic flow field. The displacement time history curve and the variation of the wind speed locking zone are obtained. The variation law of the three-point force coefficient and the fluid-solid coupling phenomenon in the dynamic flow field are analyzed. The four-order implicit Runge-Kutta method is embedded in the ANSYS-FLUENT in the form of a self-compiled UDF program. The typical members of Chaotianmen Bridge are simulated by vortex-induced vibration simulation. The wind speed, wind attack angle and damping ratio are compared and analyzed respectively. In the design of the bridge, the wind speed, damping and wind attack angle should be avoided, and the resonance and the failure speed of the structure should be avoided when the bridge is designed by the most unfavorable wind attack angle and damping ratio, while designing the bridge, it is necessary to avoid the wind speed, damping and wind attack angle of vortex-induced vibration as far as possible.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U441.3

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