Longitudinal Wind Loads And Wind-Induced Responses Of Long-Span Cable-Stayed Bridges

With the increasing span of cable-stayed bridges,the longitudinal wind load problem has become one of the controlling factors of the bridge design when designed according to the wind resistance specification.In this thesis,a numerical simulation method is used to study the aerodynamic force of the cable,bridge tower and truss girder of long-span cable-stayed bridges in the longitudinal wind.And it examines the aerodynamic interference effects of multi-rope cables,multi-limb towers and cables with tower.It uses the wind tunnel test method to test the longitudinal wind load,and examines the influence of factors such as angle.Finally,this work analyses the longitudinal buffeting response,based on the aerodynamic force of each structure.The specific research work is described as follows:1)A three-dimensional model is established for a simple cable which don't consider the groove and the spiral.The aerodynamic parameters of the space attitude cable are measured.It studies the influence of angle and declination on the cable aerodynamic force,analyzes the aerodynamic interference phenomenon of spatial multi-cable.The results show that the cable aerodynamic force is affected by the angle,and the drag of the leeward side cable in the double-row cable gradually approaches the value of the windward as the spacing increases.2)It analyzes the distribution of the aerodynamic force of multi-rope cables along the bridge tower by three-dimensional model.The results show that the forward resistance coefficient of the tower changes little with height.The change of spacing is obvious to the aerodynamic interference of multi-limb tower.The cable adjacent to the bridge tower is very significantly aerodynamically disturbed by the bridge tower.3)In the wind tunnel,the change of the aerodynamic force with the wind declination of the truss beam is measured.The influence of the compensation segment on the test results is analyzed.The results show that the maximum longitudinal resistance coefficient of the truss beam does not occur when the wind is fully compliant.And whether to set the compensation segment has a significant impact on the test results.The wind load of truss beam can be obtained more accurately by increasing the length of compensation section appropriately.4)Based on ANSYS transient analysis,a time-history analysis method for longitudinal buffeting response of long-span cable-stayed bridges is proposed.Combined with the actual project,the longitudinal buffeting response of cable-stayed bridges is studied,the difference between the actual calculated value and the calculated value of the specification is compared.