Experimental And Theoretical Investigation of Bridge Motion in Turbulent Flow

运动稳定性和统计特性 大跨度桥梁的反应， 研究了湍流风激励 从实验和理论上来说 项目 实验研究是 在桥梁截面模型上进行， 水道设施。 相似性 模型与 通过适当比例来满足原型 模型，并通过将模型连接到 位于空中的重型气缸 水道外的房间。 流体 由结构运动引起的力是 当模型被编程为 以给定模式正弦振荡 通过一系列的频率。 两者 耦合型力（例如， 扭转运动）和非耦合型 力（例如，垂直方向引起的升力 弯曲运动）进行测量。 理论 桥梁运动模型，然后制定 将这种实验确定的 流体力产生机制和运动 稳定边界和结构响应 计算的理论模型。 最后，理论预测是 与另一组实验相比， 当结构模型被 由特定平均值的流体流激发 速度和湍流水平。 的 比较提供了进一步的基础 完善理论模型。 流 并进行了可视化实验 来获得对结构的基本见解- 流体相互作用 速度场 从流动可视化中获得的数据提供了 用于计算流体的附加装置 对结构模型的作用力。

Motion stability and statistical properties of the response of long-span bridges under turbulent wind excitations are investigated experimentally and theoretically in this project. Experimental investigation is conducted on bridge sectional models in a water-channel facility. Similarity requirements between a model and the prototype are met by suitably proportioning the model, and by connecting the model to heavy cylinders which are located in the air chambers outside the water channel. Fluid forces induced by the structural motion are measured when a model is programmed to oscillate sinusoidally in a given mode through a range of frequencies. Both the coupled type forces (e.g. lift induced by the torsional motion), and the uncoupled type forces (e.g. lift induced by the vertical bending motion) are measured. Theoretical models for bridge motion are then formulated to incorporate such experimentally determined fluid-force generating mechanisms, and motion stability boundaries and structural responses are computed for the theoretical models. Finally, the theoretical predictions are compared with another set of experimental results obtained when a structural model is excited by fluid flows of specified mean velocities and turbulence levels. The comparison provides a basis for further refinement of theoretical models. Flow visualization experiments are also conducted to gain fundamental insights into structure- fluid interaction. The velocity field obtained from flow visualization provides additional means for calculating the fluid forces on structural models.