Theoretical investigation of coupled rain-wind effects on the dynamics of continuous stay cables

Abstract
Rain-wind induced vibrations present a serious risk to the durability and lifespan of cable-stayed bridges. This study investigates the complex dynamics of continuous stay cables with a moving water rivulet under pulsating wind conditions. A previously established theoretical model of coupled in-plane vibrations for such cables is employed. Experimental time-histories of three-dimensional pulsating wind speed, acquired from wind tunnel tests, serve as the forcing function in the analysis. The cable’s dynamic response was assessed through analyses in both the temporal and spectral domains, complemented by parametric studies to systematically investigate the influence of key parameters. Results demonstrate that rain-wind induced vibrations predominantly excite odd-order modes, with the rivulet's oscillation frequency closely matching the fundamental cable frequency, albeit with the presence of second-harmonic components. A possible mode-conversion tendency is observed during the vibration process under the adopted excitation and parameter conditions. Increasing the structural damping effectively mitigates vibration amplitudes without altering the critical wind speed for instability onset. Increasing the rivulet’s linear mass density raises both the cable’s oscillation amplitude and the critical wind velocity. Furthermore, the comparison with the uniform wind condition indicates that the simplified uniform wind model may provide only a preliminary estimate of the trend and order of magnitude of the maximum displacement under the examined parameter range. It should not be regarded as a reliable substitute for pulsating wind excitation when the critical wind speed, peak-response wind speed, or detailed modal evolution is of interest.