s paper addresses the measurement of eight flutter derivatives of a typical oblique strip of the Tsing Ma bridge deck under skew winds. The wind tunnel test technique developed for this measurement includes the design of oblique sectional model, the development of a dynamic test rig, and the application of unifying least-square (ULS) method for identification. The eight identified flutter derivatives of discrete values are first fitted to obtain eight flutter derivative curves as functions of both wind inclination and yaw angle. Based on these curves, the effects of wind inclination and yaw angle on aeroelastic damping and stiffness, in particular on critical wind speed, are then discussed. Furthermore, the measured flutter derivatives of the bridge deck under skew winds are compared with those obtained from the empirical formulae derived from the skew wind theory. Finally, the critical wind speeds from the measured flutter derivative A2• curves are also compared with those from the A2•curves estimated by the empirical formulae. © 2002 Elsevier Science Ltd. All rights reserved.

The finite-element-based framework for buffeting analysis of long-span cable-supported bridges under skew winds has been presented in Part 1 of this paper. The framework is now applied to the Tsing Ma Suspension Bridge in Hong Kong as a case study. The wind velocities and bridge responses measured by the Wind and Structural Health Monitoring System (WASHMS) of the bridge during Typhoon Sam in 1999 are first analyzed to find the skew wind characteristics surrounding the bridge, the modal damping ratios and acceleration responses of the bridge. The buffeting responses of the bridge under skew winds during Typhoon Sam are then computed using the wind characteristics and modal damping ratios measured from the field and the aerodynamic coefficients and flutter derivatives of the bridge deck and tower measured from the wind tunnel under skew winds. The computed acceleration responses of the bridge deck and cable are finally compared with the responses measured from the field. The comparison is found to be satisfactory in general and the case study forms a good practical demonstration for the verification of the proposed method for buffeting analysis of long-span cable-supported bridges under skew winds.

This paper aims to measure six static aerodynamic coefficients, while a companion paper addresses the measurement of eight flutter derivatives, of a typical oblique strip of the Tsing Ma suspension bridge deck under skew winds. The wind tunnel test technique developed for the aerodynamic coefficient measurement includes the design of oblique sectional models, the development of a test rig and a measurement system, and the analysis of test results. The effects of model end angle on the aerodynamic coefficients are investigated and found to be very small on lift, drag and pitching moment coefficients. The measured results are then fitted to obtain the six aerodynamic coefficient curves as functions of both wind inclination and yaw angle, which will be used in a later comparison of buffeting response of the bridge between field measurement and analysis. The measurement results reveal that the drag, lift and pitching moment coefficients are much larger than the crosswind force, rolling moment and yawing moment coefficients. The variation of lift coefficient with wind yaw angle is small, but the value of drag coefficient decreases with increasing wind yaw angle and the value of pitching moment coefficient increases with increasing wind yaw angle. The obtained six aerodynamic coefficient curves are also used to examine the currently used cosine rule for buffeting analysis of a bridge under yaw winds. It is found that the traditional cosine rule is generally inadequate, particularly in the cases of large wind yaw angle.

介绍了所编制的实桥环境随机振动测试数据处理及固有模态识别程序EDPFDM。该程序以频域法为基础，可对经实桥分组环境随机振动测试而得的大量数据进行快速自谱、互谱及相位差和凝聚性分析，从而识别出桥梁的固有模态及对应的结构阻尼比的估计范围。以香港汲水门大桥固有模态环境随机振动测试为实例，结合用MSC- NASTRAN通用程序的模态分析结果，证明了程序EDPFDM的效率和可靠性。

节段模型风洞试验是研究涡激共振风速锁定范围和最大振动幅值的一种重要手段。基于一个具有自激特性的经验线性涡激力模型，从涡激共振微分方程出发，推导了涡激共振试验节段模型质量系统模拟公式，并建立了相应的模型与实桥之间涡激共振幅值的换算关系，给出了涡激共振幅值的振型修正系数和阻尼修正系数公式。由此，通过合理的质量系统模拟和响应幅值换算，可在二维的涡激共振节段模型试验中考虑实桥的结构和振动的三维特性的影响。