Characteristics of vertical motion of raindrops in a three-dimensional turbulent wind field and response of rain-wind induced vibration of cable-net structural system of FAST
To reveal the dynamic response characteristics of large-span spatial structures under the co-effect of wind and rain,the vertical velocity variations of raindrops in a three-dimensional turbulent wind field were investigated in this paper.The motion equations of each raindrop were derived in a three-dimensional turbulent wind field,which could reveal their falling trajectories and velocities results.Besides,the concept of vertical velocity ratio of raindrops was introduced,and the recommended ratio values at a certain level of confidence were obtained through the construction of rain pressure probability distribution.Multivariate nonlinear regression analysis was applied to establishing a fitting formula of recommended value of vertical velocity ratio and calculation for the vertical velocity of raindrops was confirmed.Finally,given that both the positive and negative surfaces of general structures could collide with raindrops,a calculation model of rain load for general structures was established,and the response of the cable-net structural system of FAST to the co-effect of wind and rain was investigated.The results show that the raindrops exhibit complex and nonlinear motion characteristics in a three-dimensional turbulent wind field,and the vertical terminal velocity of raindrops is not consistent with empirical vertical terminal velocity any more.Under the co-effect of wind and rain,the average translational displacement of the FAST cable network nodes,which is induced by rain loads,reaches 39.7％of the total average,illustrating a large impact of rain loads on the dynamic response of large-span spatial flexible structures.The study concludes that the co-effect of wind and rain on the large-span spatial flexible structures cannot be neglected in structural design.
cable-net structural system of FASTthree-dimensional turbulent wind fieldwind-driven rainvertical terminal velocity of raindropsrain load
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