Framework for sensitivity and uncertainty quantification in the flutter assessment of bridges
Framework for sensitivity and uncertainty quantification in the flutter assessment of bridges
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DOI：
10.1016/j.probengmech.2015.12.007
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发表时间：
2016-01-01
影响因子：
2.6
通讯作者：
Morgenthal, Guido
中科院分区：
文献类型：
--
作者：
Abbas, Tajammal;Morgenthal, Guido
风引起的气动失稳现象是大跨度悬索桥的主要设计准则。如果风速超过桥梁的临界颤振速度，则构成极限状态。因此，颤振边界的预测需要精确和鲁棒的模型。介绍了确定颤振稳定极限的最新理论。通常桥面是海崖的，因此风作用下的气动弹性力必须在风洞中进行实验评估或通过计算流体动力学（CFD）模拟进行数值计算。自激力的建模使用通过CFD强迫振动模拟截面模型获得的气动导数。通过求解特征值问题计算两自由度颤振极限，并利用元模型技术进行概率颤振分析以评估参数不确定性的影响。在CFD模拟中对桥梁部分进行了数值模拟。这里颤振导数被认为是随机变量。颤振现象进行灵敏度分析的方法。通过考虑颤振极限的概率分布，考虑了颤振导数和结构参数的不确定性的灵敏度。颤振极限的一个显着的影响，包括不确定性的颤振导数，由于不同的解释分散在CFD模拟。结果表明，所提出的概率颤振分析方法为颤振极限的预测精度提供了扩展的信息，最终目的是建立一种基于概率输入参数的颤振极限估计方法。这样的工具可能是有用的桥梁工程师在早期设计阶段。这项研究表明了这方面必须克服的困难，但也强调了一些有趣且有希望的结果。(C)2015爱思唯尔有限公司版权所有。
The phenomenon of aerodynamic instability caused by wind is usually a major design criterion for long span cable-supported bridges. If the wind speed exceeds the critical flutter speed of the bridge, this constitutes an Ultimate Limit State. The prediction of the flutter boundary therefore requires accurate and robust models. The state-of-the-art theory concerning determination of the flutter stability limit is presented. Usually bridge decks are bluff and therefore the aeroelastic forces under wind action have to be experimentally evaluated in wind tunnels or numerically computed through Computational Fluid Dynamics (CFD) simulations. The self-excited forces are modelled using aerodynamic derivatives obtained through CFD forced vibration simulations on a section model. The two-degree-of-freedom flutter limit is computed by solving the Eigenvalue problem.A probabilistic flutter analysis utilizing a meta-modelling technique is used to evaluate the effect of parameter uncertainty. A bridge section is numerically modelled in the CFD simulations. Here flutter derivatives are considered as random variables. A methodology for carrying out sensitivity analysis of the flutter phenomenon is developed. The sensitivity with respect to the uncertainty of flutter derivatives and structural parameters is considered by taking into account the probability distribution of the flutter limit. A significant influence on the flutter limit is found by including uncertainties of the flutter derivatives due to different interpretations of scatter in the CFD simulations. The results indicate that the proposed probabilistic flutter analysis provides extended information concerning the accuracy in the prediction of flutter limits.The final aim is to set up a method to estimate the flutter limit with probabilistic input parameters. Such a tool could be useful for bridge engineers at early design stages. This study shows the difficulties in this regard which have to be overcome but also highlights some interesting and promising results. (C) 2015 Elsevier Ltd. All rights reserved.