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首页> 外文期刊>Journal of Wind Engineering and Industrial Aerodynamics: The Journal of the International Association for Wind Engineering >Aerodynamic instability performance of twin box girders for long-span bridges
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Aerodynamic instability performance of twin box girders for long-span bridges

机译：大跨度桥梁双箱梁的气动失稳性能

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Twin box girders are a popular choice among long-span bridge engineers, and the aerodynamic performance of such a system is critical to the stability of a bridge under wind excitation. Two groups of twin-box girders with six representative slot width ratios varying from 0% to 100% were utilised to investigate the influence of different wind fairing shapes on aerodynamic instability performance for both torsional divergence and flutter of the girders. The girders with two wind fairing shapes for various slot ratios were investigated by wind tunnel tests and theoretical analyses. Based on the experimental results of static wind loads and critical flutter wind velocities, the symmetry of wind fairing only showed an influence on the development pattern of drag force coefficients and the flutter performance was only significantly affected when the slot width ratio was over 40%. It is also shown that the effect of structural stiffness variation caused by the change of slot width ratio cannot be neglected in stationary torsional divergence analysis. The flutter performance of twin box girders with asymmetric wind fairing is sensitive to slot width ratio due to the existence of optimal slot width, which is opposite to the case with symmetric wind fairing, especially when this ratio is over 40%. Different aerodynamic damping parts contributing to the torsional aerodynamic damping and the participation level of each degree of freedom (DOF) were analysed through a two-dimensional three degree of freedom (2D-3DOF) method, and the results indicate that the improvement in flutter performance can be mainly attributed to the decrease in aerodynamic negative damping Part F (caused by the couple effect of the torsional and vertical motion) and the increase of participation level in heaving motion at the flutter onset. Particle Image Velocimetry (PIV) techniques were further employed to reveal that the change in central slot width ratio and the symmetry of wind fairing have a great influence on the vortices' characteristics, especially in the central slot region when the slot ratio is over 40%. This was determined by observing the flow structures around the deck sections in terms of wind velocity field and vortex characteristics. (C) 2015 Elsevier Ltd. All rights reserved.
机译：在大跨度桥梁工程师中，双箱梁是一种流行的选择，这种系统的空气动力学性能对于风激励下桥梁的稳定性至关重要。两组具有六个典型槽宽比（从0％到100％不等）的双箱形梁被用于研究不同风整流罩形状对梁的扭转发散和颤动的气动不稳定性的影响。通过风洞试验和理论分析，研究了两种具有不同开槽率的整流罩形状的大梁。基于静风载荷和临界颤振风速的实验结果，整流罩的对称性仅对阻力系数的发展方式产生影响，并且当槽宽比超过40％时，颤振性能仅受到显着影响。研究还表明，在固定扭转发散分析中，不能忽略缝宽比变化引起的结构刚度变化的影响。由于存在最佳的槽缝宽度，具有不对称整流罩的双箱梁的颤振性能对槽缝宽度比敏感，这与对称整流罩的情况相反，尤其是当该比率超过40％时。通过二维三自由度（2D-3DOF）方法分析了影响空气动力学阻尼的不同空气动力学阻尼零件和每个自由度（DOF）的参与程度，结果表明颤振性能得到了改善主要原因可归因于空气动力学负阻尼F部分的减少（由扭转和垂直运动的耦合作用引起）以及颤振开始时参与起伏运动的参与程度的增加。进一步利用粒子图像测速技术（PIV）揭示了中心槽宽比的变化和整流罩的对称性对涡流的特性有很大的影响，尤其是当槽率超过40％时，在中心槽区中。这是通过观察围绕风速场和涡流特性的甲板部分周围的流动结构来确定的。 （C）2015 Elsevier Ltd.保留所有权利。

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