Structural Stability Analysis Of Suspension Bridge With The Action Of Static Wind During Construction

The problem of wind resistance of suspension bridges has attracted much attention.A large number of scholars at home and abroad have done a lot of research on it and achieved many research results.However,previous studies mostly focused on long-span suspension bridges,while the research on wind stability of pedestrian suspension bridges with relatively small span is rare.A large number of practices show that the stifimess and overall structural performance of suspension bridges are significantly lower than those of completed bridges due to the incomplete system transformation in the construction stage.Under this condition,the suspension bridges are prone to instability.Therefore,in order to ensure the safety of bridge structure during construction,it is necessary to study the stability of suspension bridge under static wind during construction.Based on the theory of non-linear finite displacement and the engineering background of ShuiyUn Bridge,this paper studies the stability of suspension bridge under static wind during the hoisting construction of stififening girder.The main contents are as follows:(1)Based on computational fluid dynamics(CFD)numerical simulation method,the statie three-component coefficients of stiffened beams during construction are analyzed numerically,and the static three-component coefficients of stiffened beams at different wind attack angles are obtained.The numerical simulation and wind tunnel test results are compared and analyzed with specific examples.The results show that the numerical simulation resullts are in good agreement with the experimental results,which verifies the accuracy of the static three-component force coefficient numerical simulation method in this paper.(2)Through the wind tunnel test of the main girder segment model,the static three-component force coefficients of stiffened girder tinder the approximate bridge state are measured and studied with the change of wind attack angle.The results show that when the suspension bridge approaches the completed state,due to the influence of deck pavement and accessory structure,the approximate Streamlined Flat steel box girder will become the approximate blunt section steel box girder,and the static three-force coefficient of stiffening girder will change obviously.(3)Based on the double effects of geometric nonlinearity and static wind load nonlinearity of suspension bridges,and considering the shortcomings of two-dimensional static wind model,the three-dimensional finite element model of construction phase is established by using ANSYS finite element software,and the wind load is transformed into equivalent load to calculate the wind-resistant stability of the structure model.(4)The static wind stability of stiffened girder under symmetrical and asymmetrical hoisting is analyzed and compared with that under approximate bridge condition.The results show that the critical wind speed of suspension bridge in construction stage is less than that in approximate completion stage;in the process of hoisting stiffened beams,the critical wind speed of static instability increases gradually with the increase of the number of beam segments,but the increase is small;after all hoisting of stiffened beams,the critical wind speed of static instability decreases;compared with symmetrical hoisting and asymmetrical hoisting of stiffened beams.It can be seen that the critical wind speed of static instability in the case of asymmetrical lifting of stiffened beams is slightly larger than that in the case of symmetrical lifting of stiffened beams.