Study on Aerodynamic Stability of Super-long Spanned Bridge and Its Structural Dynamics

大跨度桥梁上部结构设计的主要问题是气动稳定性问题。因此，了解施工现场自然风的行为及其气动特性是一项重要的任务。本研究利用桥梁结构气动响应的失效概率指标，于1987年确定了颤振破坏的第一阶段作为失效概率的对象。涡激振荡也被反对。在1988年，失败概率在1987年。涡激振荡也被反对。1988年，在考虑涡激振荡和抖振影响的情况下确定了失效概率，并确定了疲劳引起的损伤累积量，以评估疲劳失效。此外，在对自然风进行评价时，由于桥梁结构的气动性能和自然风的特性在很大程度上取决于风向，因此确定了每个风向下强风和正常风的风速特性。根据这些结果，确定了7座悬索桥在强风作用下的颤振破坏概率。对于双层桥梁，腹板和弦杆翼缘的厚度比其他桥梁要厚，评估结果在安全方面有所下降。针对箱梁桥，根据风洞试验得到的振动响应特征，提出了涡激振荡和抖振双重破坏概率的计算方法。利用该方法的评估结果表明，失效概率主要取决于涡激振荡的第一模态。研究还发现，失效概率对材料强度的变化极为敏感。为了估计强风，我们使用了日本133个地方15年的风力数据。确定了大风区、威布尔参数和台风因子。最后，建立了台风因子图。在此基础上，提出了自然风的特点及其对结构稳定性影响的评价。研究结果对评价大跨度桥梁的气动稳定性有一定的参考价值。少

Main problem in the design of superstructure of long-span bridge is the aerodynamic stability. Therefore, it is an essential task to know the behavior of natural wind at the construction site as well as its aerodynamic properties.In this research study, by using the failure probability index of the bridge structure to aerodynamic response, the first stage of failure due to flutter was determined as an object of the failure probability in 1987. The vortex-induced oscillation was also objected. In 1988, failure probability in 1987. the vortex-induced oscillation was also objected. in 1988, failure probability was determined with the consideration of both the effect of vortex-induced oscillation and buffeting, and damage accumulation resulting from fatigue was also determined in order to evaluate fatigue failure.Furthermore, for evaluating natural wind, because both an aerodynamic behavior of bridge structures and the characteristics of natural wind are strongly depended on the wind direc … More tion, wind speed characteristics of strong and normal wind were determined for each wind direction.From these results, failure probability of seven suspension bridges due to flutter under strong wind were determined. For double-deck bridges, the thickness of web and flange of chord member is thicker than other bridges, and the result of the evaluation fell in the safety side. For boxgirder bridge, based on the characteristics of vibration response obtained from wind tunnel test, the method for evaluating failure probability due to both vortex-induced oscillation and buffeting is proposed. Evaluated result by using this method showed that the failure probability depends mainly on the first mode of vortex-induced oscillation. It was also found that the failure probability is extremely sensitive to the material strenght.For estimating strong wind, the wind data of the 133 places in Japan for 15 years were used. Region of strong wind, Weibul parameter, and typhoon factor were determined. Finally, the map of typhoon factor was established.From this research, the characteristics of natural wind and the evaluation of its effect on the structural stability were proposed. This results are considered to be useful for evaluation of the aerodynamic stability of the long-span bridge. Less