Fundamental Study on Effect of Turbulence on Aerodynamic Response of Bridge Structures

为了阐明湍流对桥梁结构气动振动现象的影响和大气湍流的特性，在工程实施期间，主要讨论了以下几个方面：（1）涡激振荡的产生机理--应用声学实验和湍流效应（1990）;（2）缆索--空气动力学和湍流效应（1990）;（3）自然强风作用下桥梁结构的安全性评价（1990），（4）大气湍流模拟（1990），（5）湍流对海崖六边形桥梁截面涡激振动的影响（1991），（6）雷诺数对矩形截面切角气动响应的影响（1991），（7）表面粗糙度参数的评估（1991）。因此，在某些情况下观察到湍流的不稳定效应，例如带扶手的海崖六边形横截面的涡激振荡，倾斜缆索的风雨诱导振动等。此外，结果表明，湍流的影响可以用速度脉动对剪切层不稳定性的频率依赖性来解释是围绕着一个海崖体发展起来的雷诺数（基于物体高度）对涡激振动最大振幅的影响，以及切角海崖矩形截面驰振的临界风速。最新开发了地表粗糙度参数的评估方法以及野外自然风观测设备，并证实了其适用性。提出了考虑空气动力响应、自然风等特性的桥梁结构安全性评估方法。

In order to clarify the effect of flow turbulence on aerodynamic vibration phenomena for bridge structures and characteristics of atmospheric turbulence, the following items are mainly discussed during the term of project ;(1) Generation mechanism of vortex-induced oscillation-by applied sound experiment and effect of turbulence (1990),(2) Cable-aerodynamics and effect of turbulence (1990),(3) Safety evaluation of bridge structures due to strong natural winds (1990),(4) Simulation of atmospheric turbulence (1990),(5) Turbulence effect on vortex-induced oscillation for bluff hexagonal bridge girder section (1991),(6) Reynolds number effect on aerodynamic response of rectangular cross section with corner-cut (1991),(7) Evaluation of surface roughness parameters (1991).Consequently, the destabilization effects of turbulence were observed in some cases, such as vortex-induced oscillation for bluff hexagonal cross section with handrails, rain-wind induced vibration of inclined cable, and so on. Besides, it was concluded that the effect of turbulence could be explained in terms of frequency dependence of velocity fluctuation on the instability of shear layer being developed around a bluff body. Strong Influence of Reynolds number (based on the height of body) upon maximum amplitude of vortex-induced oscillation, critical wind velocity of galloping oscillation was also clarified for a bluff rectangular cross section with corner-cut. The evaluation method of surface roughness parameters as well as the equipment for field observation of natural winds were newly developed and confirmed their applicability. Safety evaluation for bridge structures, in which the properties of aerodynamic responses, natural winds are taken into account, was also proposed.