大跨悬索桥非平稳抖振位移响应时域分析

发布时间：2019-01-18 18:00

【摘要】：近几十年来，随着桥梁跨度的逐渐增大，桥梁刚度越来越小，风致振动问题日益凸显，抗风设计已成为桥梁设计必不可少的环节。其中桥梁抖振响应计算经过多年的发展已趋于成熟。然而，近年来有实测风速数据表明，山区复杂地形风环境下，脉动风速具有较强的非平稳特性，不能视为平稳随机过程进行风振响应计算，传统的平稳抖振响应分析已经不能满足此类风环境下的桥梁响应分析了。本文研究复杂风环境下悬索桥的非平稳抖振响应，将风视为非平稳随机过程，分析非平稳风速对位移抖振响应的影响。本研究对山区复杂风环境下的桥梁设计及安全评估具有重要意义。本文运用谐波合成法合成三维空间多点平稳脉动风速，基于演变谱理论，取调制函数将平稳脉动风速调制形成非平稳风速，，并将风速时程进行荷载化处理；建立ANSYS有限元模型，基于APDL语言编制非平稳抖振响应分析程序，采用非平稳风速荷载化结果对主梁、悬索、桥塔、桥墩加载，进行全桥抖振响应时域分析；最后进行非平稳抖振响应参数分析，研究了风攻角、气动导纳、自激力等因素对非平稳抖振响应的影响。结果表明：经过本文选取的调制函数调制后，非平稳风速的湍流强度值与平稳风速相差较大；桥面板的非平稳抖振响应要远大于桥塔的响应，且最大值出现在横桥向的跨中位置附近；风攻角对主梁竖向抖振响应具有较大的影响，对横桥向及转角影响较小，对桥塔几乎没有影响；气动导纳对桥梁抖振响应影响显著：考虑气动导纳后，抖振响应明显降低，表明实际工程中不考虑气动导纳的设计方法是偏于安全的；气动自激力具有发散作用，考虑气动自激力后桥梁抖振响应增幅显著，尤其对主梁竖向响应，甚至起到主导作用；考虑自激力后主梁竖向非平稳抖振响应远远大于不考虑自激力时的情况，实际工程中可采用提高主跨刚度的方式，避免风与结构的耦合振动效应。
[Abstract]:In recent decades, with the gradual increase of bridge span, the stiffness of bridge becomes smaller and smaller, and the problem of wind-induced vibration becomes more and more prominent. Wind resistant design has become an indispensable link in bridge design. The buffeting response calculation of bridges has matured after years of development. However, the measured wind speed data in recent years show that the fluctuating wind speed has a strong non-stationary characteristic under the complex terrain wind environment in mountainous area, and can not be regarded as a stationary random process to calculate the wind-induced vibration response. The traditional steady buffeting response analysis can not satisfy the bridge response analysis in this kind of wind environment. In this paper, the non-stationary buffeting responses of suspension bridges under complex wind conditions are studied. The wind is regarded as a non-stationary stochastic process, and the influence of non-stationary wind velocity on the buffeting response of displacement is analyzed. This study is of great significance to bridge design and safety assessment under complex wind environment in mountainous area. In this paper, the harmonic synthesis method is used to synthesize multi-point stationary pulsating wind speed in three-dimensional space. Based on the theory of evolution spectrum, the stationary pulsating wind speed is modulated into non-stationary wind speed by the modulation function, and the wind speed time history is subjected to load treatment. The ANSYS finite element model is established, and the non-stationary buffeting response analysis program is compiled based on APDL language. The buffeting response of the whole bridge is analyzed in time domain by using the non-stationary wind load results to load the main beam, suspension cable, bridge tower and pier. Finally, the non-stationary buffeting response parameters are analyzed, and the effects of wind attack angle, aerodynamic admittance and self-excitation force on the non-stationary buffeting response are studied. The results show that the turbulence intensity of non-stationary wind speed is significantly different from that of stationary wind speed after the modulation function selected in this paper. The non-stationary buffeting response of the deck is much larger than that of the tower, and the maximum appears near the midspan of the transverse bridge. The wind attack angle has a great influence on the vertical buffeting response of the main beam, but has little effect on the transverse bridge direction and the turning angle, but has little effect on the bridge tower. The effect of aerodynamic admittance on bridge buffeting response is significant: considering aerodynamic admittance, buffeting response is obviously reduced, which indicates that the design method of not considering aerodynamic admittance in practical engineering is relatively safe; The aerodynamic self-excitation force has the divergence effect, the bridge buffeting response increases obviously after considering the aerodynamic self-excited force, especially for the vertical response of the main beam, and even plays a leading role. The vertical non-stationary buffeting response of the main beam considering self-excited force is far larger than that of the non-self-excited force. In practical engineering, the method of increasing the stiffness of the main span can be adopted to avoid the coupling vibration effect between wind and structure.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.25;U441.3

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