Study On The Dynamic Characteristics And Aerostatic Performance Of Cable-stayed Bridge With Single Cable Plane And Low Tower

In recent years,the construction momentum of China’s low-span cable-stayed bridges has developed rapidly,but there has been a lack of specific design specifications and many key technical issues have yet to be resolved.Beigang Island and Nanjing Bridge is a cable-stayed dwarf tower cable-stayed bridge with a span of 80+138+80m and a box girder with a width of 26 m.The bridge is in a quiet sea environment and is affected by bad weather such as typhoons all year round.The issue of wind must be studied specifically.In this paper,the combination of numerical calculation and wind tunnel tests is used to study the dynamic characteristics and static wind performance of the bridge and the construction state(maximum double cantilever state)of the He-Ning Bridge.The main conclusions are as follows:1)The basic wind speed at the bridge of He-Ning Bridge is 38.4 m/s,the design reference wind speed of the completed state is 44.1 m/s,the design reference wind speed during the construction phase is 31.1 m/s,and the static gust wind speed during the completion of the bridge is 46.6 m/s.s,The static gust wind speed during the construction period is 40.7 m/s.2)The finite element method is used to establish the finite element model of the bridge and the maximum double cantilever state of the He-Ning Bridge in the large-scale general-purpose analysis software ANSYS.The results show that the first-order vertical bending frequency is 0.570 Hz and the first-order torsional frequency is 3.139 Hz.The maximum double-cantilever construction condition is the first-order vertical bending frequency of 0.309 Hz and the first-order torsional frequency of 3.202 Hz.3)Computational fluid dynamics analysis software ANSYS FLUENT was used to calculate the static force and three-component force coefficients of the 9 key sections of the variable cross-section girder and the five key sections of the bridge under different wind angles.In order to verify the accuracy of the numerical calculation,a segment model of the main beam pier top,mid-span,and middle section of the bridge tower was made.In the wind tunnel test,high-component dynamic balance measurements were used to obtain static values at different wind angles of attack.Force factor.By comparison,the results of the CFD numerical calculation in this paper satisfy the accuracy requirement.4)Based on the calculation result of the static three-component force,the effect of the equivalent static wind load is analyzed by using the gust load theory and the bridge state and construction state respectively.Computational analysis of cross-bridge wind loading and asymmetrical loading of wind loads was carried out for the bridge-to-wind and bridge-to-wind loads in the completed state.The typical location of the bridge under various conditions was given.The displacement and internal force distribution at the location can provide reference for the load combination of the bridge design.5)The critical wind speed for static wind destabilization of the He-Ning Bridge is 157m/s considering the geometric nonlinearity and nonlinear load calculation,which is much higher than the design reference wind speed.This shows that the stability of the bridge and the stability of the He-Ning Bridge meet the requirements.