Study On The Stability Performance And Design Method Of High Strength Steel Stiffened Plates Under Axial Compression

The stiffened plate is made of stiffener welded to the panel,which is a highly statically indeterminate system with a much higher carrying capacity than the regular plate,and is widely used in bridge,ship and aviation manufacturing,etc.The introduction of high-strength steel stiffened plates in the engineering can significantly smaller the cross-section under the same stress condition,decrease the steel consumption,and also lower the cost of processing and transportation of components.The highest grade of steel in Code for Design of Highway Steel Structure Bridges(JTG D64-2015)is Q420,which lacks the relevant provisions and design methods for high-strength steel.Since highstrength steel is less sensitive to initial geometrical imperfection and residual stresses than ordinary strength steel,There are obvious differences in the stability performance of ordinary strength steel components,and it is necessary to study the stability performance of high-strength steel stiffened plates.Based on the national key research and development project(2018YFC0705501-2),the experimental research and finite element analysis method are used in this paper to systematically study the axial compression stability of high-strength steel stiffened plates.The main research contents and results are as follows:(1)Axial compression experiment was carried out on 12 domestic Q420,Q500 and Q690 steel stiffened plate specimens.The test specimens included two types of stiffeners(U-ribbed stiffeners and plate ribs).Before loading,the steel mechanical properties and initial geometrical imperfections were measured,the axial compression experiment obtained the failure form,ultimate capacity,load-displacement curve and load-strain curve of the specimen.The final failure form of the specimens was influenced by the shape of initial geometrical imperfections,and the failure mode of the local buckling of the panels is the most unfavorable for the stable capacity of the U-rib stiffened plate specimen.(2)The nonlinear finite element model of plate rib stiffened plate and U-rib stiffened plate was established using the general finite element software ABAQUS.The model considered the material nonlinearity and geometric nonlinearity.A variety of residual stress models was applied to the finite element model.Then compared with the experiment results from the failure form,load-displacement curve and stable bearing capacity,the most suitable residual stress distribution model for this test was determined.(3)Based the validated finite element model,the influence of parameters such as residual stress,initial geometric defect amplitude,width-thickness ratio,slenderness ratio and steel strength grade on the stable capacity of the stiffened plate were studied,270 finite element calculation examples of the axial compressive stability of plate rib stiffened plate and U rib stiffened plate were completed.(4)The experiment results and parameter analysis results were compared with current design methods of stable capacity of stiffened plates.Based on the parameter analysis results,the local buckling reduction coefficients of the two types of stiffened plates are fitted and the column curves applicable to different grades of two types of stiffened plates are determined,the recommended calculation formula of the stable capacity of high-strength steel stiffened plate is proposed,the formula is in good agreement with the parameter analysis results.