Wind-rain-induced vibration and control of stay cables in cable-stayed bridges

This thesis aims to develop a systematic theoretical framework, supported by field measurements and wind tunnel test results, to explore the mechanisms of wind-rain-induced cable vibration, to understand wind-rain-induced vibration behavior of prototype stay cables, and to assess the effectiveness of active stiffness control in mitigating wind-rain-induced vibration of prototype stay cables.; The wind rain tunnel tests are performed to investigate the formation and position of water rivulet on the surface of inclined stationary cylinder immerged in a uniform wind field under different wind speeds and various cylinder inclinations, wind yaw angles, cylinder diameters, and water flow rates. The experimental results are then described and discussed in detail to enhance the understanding of the formation and position of the upper rivulet. The relationship between the rivulet position and the incident mean wind speed, obtained here, are used in the development of the theoretical framework.; A single-degree-of-freedom (SDOF) analytical model, taking into account the interaction between wind, upper rivulet and cable, is developed to investigate the steady-state wind-rain-induced cable vibration. The circumferential oscillation of the upper rivulet is assumed to be harmonic and its amplitude is quantified using the measured results from wind rain tunnel tests. The developed SDOF analytical model is then verified through the comparisons between the analytical and measured results for some cable models tested in either a wind tunnel with fixed artificial rivulets or a wind-rain tunnel with moving rivulets. The mechanisms of wind-rain-induced cable vibration are also explored using this analytical model. It is found that the analytical model is able to capture main vibration features of inclined cylinders with moving rivulet, such as velocity-restricted vibration and amplitude-restricted vibration. The occurrence of velocity- and amplitude-restricted vibration is mainly because of alternating aerodynamic damping ratio and/or alternating excitation force due to the interaction between rivulet motion, cable motion and wind. The proposed analytical model can also predict the vibration of horizontal cylinder with fixed artificial rivulet. (Abstract shortened by UMI.)...