非平稳风场作用下大跨度桥梁抖振响应时域分析

发布时间：2018-03-13 09:41

本文选题：悬索桥　切入点：时间步长　出处：《合肥工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：近几十年来,随着桥梁向大跨度、超大跨度的不断发展,桥梁柔度显得越来越大,对桥梁结构风致振动问题的研究显得越来越重要,抗风设计已成为桥梁设计环节中必不可少的部分。虽然基于平稳风场作用下桥梁结构抖振响应分析的发展已趋于成熟,然而,近些年来对实测风速数据统计分析表明,强风场或山区复杂地形风场环境下,脉动风速具有显著的非平稳特性,不能再视为平稳随机过程脉动风作用下的桥梁抖振响应分析。本文以云南普立特大跨度悬索桥为研究对象,首先根据ANSYS建立该桥的三维有限元计算模型,并基于结构动力响应分析及模态分析理论,推导了大跨度模态贡献度系数及最优时间步长的计算公式,其次据桥址处风特性模拟出该桥的平稳态三维脉动风,再此基础上进行了桥梁抖振响应时域分析,重点研究了自激力考虑与否及不同时间步长△t因素对大跨度悬索桥风致抖振响应的影响。研究结果表明：考虑自激力结果抖振响应在部分方向起正阻尼作用,在垂直向呈现的效应比横桥向及扭转向上更加显著,不考虑自激力会导致桥梁抖振响应结果失真,为了精细化的分析,不能忽略其因素的影响；由于对最优时间步长△t=0.05s与设置时间步长△t=0.25s分别计算抖振响应的结果存在显著差异性,证明了采取最优时间步长对结构的分析与计算是十分必要的,此结果对大跨度悬索桥风致抖振分析具有参考价值。本文基于改进的谐波合成法的思想及实测强风数据经统计处理后拟合得到的时变参数来成功地模拟了非平稳风速,然后对强风场作用下的时变平均风荷载、非平稳抖振力及非平稳自激力进行了详细的阐述,最后在此基础上进行非平稳风场作用下的桥梁抖振响应时域分析,同时进行了不同工况下普立特大跨度悬索桥的时变平均风及非平稳抖振响应的计算与比较,重点研究了考虑时变平均风及时变演变谱因素对大跨度桥梁抖振响应时域分析的影响,研究结果表明在强风场作用下,有必要考虑时变平均风及演变谱对大跨度桥梁抖振响应的影响。
[Abstract]:In recent decades, with the continuous development of large span and long span, the flexibility of bridge becomes more and more large, and the study of wind-induced vibration of bridge structure becomes more and more important. Wind resistant design has become an essential part of bridge design. Although the development of buffeting response analysis of bridge structure based on stationary wind field has become mature, the statistical analysis of measured wind speed data in recent years shows that, Under the strong wind field or the complicated terrain wind field in mountainous area, the fluctuating wind speed has remarkable non-stationary characteristics. The buffeting response of bridges under the action of pulsating wind can no longer be regarded as a stationary stochastic process. In this paper, a three-dimensional finite element model of the bridge is established based on ANSYS. Based on the structural dynamic response analysis and modal analysis theory, the formulas of the long-span modal contribution coefficient and the optimal time step size are derived. Secondly, according to the wind characteristics at the bridge site, the steady three-dimensional pulsating wind is simulated. Then the buffeting response of the bridge is analyzed in time domain. The effect of self-excitation force and different time step t factors on wind-induced buffeting response of long-span suspension bridge is studied. The results show that the buffeting response of long-span suspension bridge has positive damping effect in some directions considering the self-excitation force. The effect in vertical direction is more significant than that in transverse bridge direction and torsional direction, and the effect of factors can not be ignored for the sake of fine analysis, not considering the self-excitation force will lead to the distortion of the buffeting response result of the bridge. Because there is significant difference in the buffeting response between the optimal time step t0. 05 s and the set time step t0. 25 s, it is proved that it is necessary to take the optimal time step size for the analysis and calculation of the structure. This result has reference value for wind-induced buffeting analysis of long-span suspension bridges. Based on the idea of improved harmonic synthesis method and time-varying parameters fitted by statistical processing of measured strong wind data, the non-stationary wind speed is successfully simulated in this paper. Then the time-varying mean wind load, non-stationary buffeting force and non-stationary self-excitation force under strong wind field are described in detail. Finally, the time-domain analysis of bridge buffeting response under non-stationary wind field is carried out. At the same time, the time-varying mean wind and non-stationary buffeting responses of Puli long-span suspension bridge under different working conditions are calculated and compared. The time domain analysis of buffeting response of long-span bridges is mainly studied by considering the time-varying spectrum of time-varying mean wind. The results show that under the action of strong wind field, the time domain analysis of buffeting response of long-span bridges is studied. It is necessary to consider the effect of time-varying mean wind and evolution spectrum on buffeting response of long-span bridges.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3

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