Local Stability And Design Theory Of Q620 High Strength Steel Welded Box Section Axially Compressed Stub Column

In recent years,the improvement of steel production technology has brought more extensive engineering application of high strength steel.The improvement of design strength of steel reduces the area of steel structural members section,which makes the stability bearing capacity of the compression member is controlled by stability rather than strength.The traditional local stability theory of members is the effective section method(ESM),the application of newly proposed stability design theories such as Direct Strength Method(DSM)and Continuous Strength Method(CSM)has been explored.In order to provide further reference for the design of high strength steel members,this paper focus on the axial compression test of high strength steel stub columns,and combines test investigation with finite element analysis.The stability properties and design methods of high strength components are studied.This paper completed the following works:(1)The relevant research results of high strength steel components were collected.Based on stability theory of steel columns,this paper introduced the design theories and design methods of different steel structure design codes.The core concepts of DSM and CSM were described.(2)Three material tests of 8mm steel plate were completed,and the amplitudes of local initial geometric imperfection were measured.Twenty Q620 high strength steel stub columns with welded box(square)cross section were tested under axial compression,from which the local stability properties were extracted.(3)Finite element models of test columns were established by finite element software ABAQUS,considering initial geometric imperfection and residual stress.The finite element models were verified through comparing the FEA results with test results.(4)Based on finite element models and collected stub column test results,the applicability of design method for high strength welded stub column was studied.Critical elastic buckling stress of the cross section was calculated by finite strip software CUFSM.Width to thickness ratio limit was also carefully discussed in this paper.Based on the direct strength method and the continuous strength method,the local stability design formula of HSS welded section stub column were proposed,and the proposed formula was compared with different steel design codes.(5)The finite element models of global and local-overall stable axial column were established to obtain the local-overall properties of columns with different slenderness ratios and width to thickness ratios.A parametric analysis was performed and the main factors affecting the stability properties of the local-overall buckling were studied.Based on the calculation formulas of the overall bearing capacity in design codes GB 50017-2017 and ANSI/AISC 360-10,formulas for calculating the local-overall stability bearing capacity of Q620 HSS welded section column were put forward respectively.The calculated results were compared with those calculated by different steel design codes.