Research Of Stability Performance And Design Method Of Hybrid Steel U Rib-Stiffened Plates Under Compression

Hybrid steel U rib-stiffened plates is the main bearing members of steel box girder bridge roof and floor.When U ribs with the motherboard using different strength grade steel design,it can improve the efficient use of materials,reduce the project cost,such U rib-stiffened plates called a hybrid steel U rib-stiffened plates.In the steel box girder design,compression stability of stiffened plates are key issue in design,and welding residual stress,initial geometrical imperfections,materials and slenderness ratio are major factors influencing the stability of stiffened plates under pressure.At present,the research about stability mainly concentrated on equal strength steel U rib-stiffened plates,few research about stability on hybrid steel U rib-stiffened plates.In order to investigate the local stability of U rib stiffened plate under compression.According to the ratio of width to thickness of U-rib web,Total of 6 specimens of plates stiffened with U-ribs is designed.According to different thickness ratio of stiffened plate,Total of 4 specimens of plates stiffened with U-ribs is designed.Experiments of the specimens under axial loads were carried out,the failure mode,stability bearing capacity and the load-displacement curve of U stiffened plat were investigated.Meanwhile,a model of quadrilateral simply supported slab is established,in which the influence of local geometric imperfections and welding residual stresses on the mechanical properties are considered.The finite element simulation results good agreement with the test results,proved the validity of numerical simulation methods of quadrilateral simply supported slab.Stability capacity of quadrilateral simply supported slab with three types of steels was calculated using shell element FEM models with overall local geometric imperfections and residual stress.Perry formula and cubic polynomial was then used to fitting the local stability reduction factor of mother board and U-rib web.In order to investigate the stability of U rib stiffened plate under compression.Total of 9 specimens of plates stiffened with U-ribs of hybrid steel types were designed and manufactured,taking structure size and material strength of the steel plate and the stiffened U-ribs as specimen variables.Experiments of the specimens under axial loads were carried out,the failure mode,stability bearing capacity and the load-displacement curve of the hybrid steel U stiffened plat were investigated.The stability mechanism of plate stiffened with U-rib of hybrid steel types under axial load is investigated,in which the members with low strength is equivalent to members with high strength as the other members by adding initial stress on it,and the distribution of the welded residual stress is also considered.A nonlinear finite element model for compressed mixed steel plate stiffened with U-rib is established,in which the influence of the boundary condition,initial geometric imperfections and welding residual stresses on the mechanical properties are considered.The finite element simulation results good agreement with the test results,proved the validity of numerical simulation methods of stability bearing of hybrid steel U rib-stiffened plates.Using the beam element FEM models(294 for each)with overall geometric imperfection and residual stress,stability capacity of totaling 882 U-rib-stiffened plates with three types of steels was calculated.And Perry formula was then used to fitting the overall stability reduction factor of compression U-rib-stiffened plate.Using the shell element FEM models,in which the influence of initial geometric imperfections and welding residual stresses on the mechanical properties are considered.The stability bearing capacity of hybrid steel U rib-stiffened plates with different strength combination and different structural dimensions is calculated.According to the overall and local stability reduction factor,Formula of stability capacity of the U-rib-stiffened plate was further proposed.