Stability Of Stiffened Curved Plate Of Steel Bridge Subjected To Biaxial Loading

The stability of stiffened plates has attracted more and more attention of scholars.At present,most of the existing literature at home and abroad is to study the stability analysis of steel box girder stiffened straight plates,while the application of curved stiffeners in bridge engineering is gradually increasing.Most of the research on cylindrical curved plates focuses on the uniaxial compression state,but in practical engineering,the stiffened plates of steel box girder will be subjected to different complex loads,which makes the stiffened plates in a complex stress state.There is no corresponding guidance in many specifications.In this thesis,the ultimate bearing capacity and failure mode of stiffened curved plate under uniaxial compression are studied through model test,which verifies the effectiveness of finite element simulation calculation.Then,the elastic stability of stiffened curved plate model under key design parametersand the nonlinear stability under bidirectional stress mode are further studied by the finite element numerical analysis method,which provides a reference for the design of curved plate in engineering.Based on the stiffened plate structure of railway box curved web of Xihoumen highway railway dual-purpose bridge on Yongzhou railway,the test model is designed according to the scale of 1:2.The boundary condition of the specimen is simply supported on four sides through appropriate limiting device,and the end of the plate rib is cut off,so that the axial pressure is completely borne by the motherboard.Three groups of parallel specimens were set for the model with the same size in the test,two of which were tested by the traditional strain displacement test method,and the other group was compared and analyzed by DIC image processing technology.The test results show that the change of bending radius does not affect the ultimate bearing capacity of stiffened plates,nor does it change the failure mode,which is dominated by overall buckling.The bearing capacity of the stiffened curved plate under this structure can be calculated approximately according to the theoretical formula in China’s highway bridge code,and the difference between them is less than 5%.After comparing the test results with the finite element simulation results,the buckling analysis of the curved stiffener model under several main parameters is carried out through the finite element software.The parameters studied are the stiffness of stiffeners,the width thickness ratio of intercostal motherboard,the length width ratio of motherboard,the bending radius and different transverse forces.The results show that under the designed stiffener structure,changing the bending radius has little effect on the buckling stress,and there will be an optimal value for the changes of other parameters to maximize the elastic buckling stress of the stiffened curved plate.When the stiffened curved plate is subjected to biaxial loading,whether in tension or compression,the buckling stress will be lower than that under uniaxial compression,and the influence of transverse tension on the elastic buckling stress is much greater than that of transverse pressure.Similarly,the nonlinear stability analysis of the ultimate bearing capacity of the stiffened curved plate with the above parameters is carried out by finite element method.The results show that the bearing capacity of the curved stiffened plate under this structure will not change with the change of parameters under uniaxial compression;Under the condition of two-way stress,the bearing capacity of the stiffened curved plate will be reduced regardless of transverse tension or compression.By increasing the radius,increasing the rib stiffness ratio,reducing the width thickness ratio of intercostal motherboard and reducing the length width ratio of the motherboard,the bearing capacity can be improved,so that the stiffened curved plate can approach the yield strength of the full section under two-way stress.