Studying On The Design Parameters Of Axial Compression Member By Q345GJ Steel

The research work on the design parameters of GJ steel has been carried out byChongqing university since2007and the uncertainty parameters of material andgeometry of Q345GJ steel has been successfully obtained recently, which made theresearch work of Q345GJ steel rise to the component stage. The experimental study oncapacity of axially loaded steel columns of Q345GJ was completed by Chongqinguniversity in2011, based on which, the theoretical analysis will be carried out in thispaper.The bending moment-axial force-curvature curves have been calculated by thenumerical program using the FORTRAN95programming language. The factors, whichhave effect on the bending moment-axis force-curvature curve such as membersbuckling on different axes, the constitutive relation of GJ steel, the residual stressmodels obtained by different testing method were discussed in this paper.Meanwhile, the numerical program based on the theory of the inverse calculationsegment length method was applied to solve the capacity of axially loaded steelcolumns of Q345GJ steel. The results form calculation and the full-scale columnstability capacity test were compared and analyzed.The uncertainty statistic parameter of Q345GJ axially compression componentresistance was obtained according to plenty of calculated data of ultimate capacitythrough theoretical analysis and the test result. Based on reliability theory, the targetreliability β equal3.2and the improved JC method considering three kinds of generalload combination was taken to get the optimal Q345GJ axially compression componentresistance partial coefficientγ Rwhich was equal to0.9092. Then the partial coefficientwas adopted to inversely calculate the reliability indices under four load combinations,which can exceed the target reliability requirements.Eventually, the value of resistance coefficient has been recommended equal to1.05.According to the compression component resistance partial coefficient by calculationand the specification of steel level difference from “Steel Plates For Building Structure”(GB/T19879-2005), the design strength of Q345GJ axially compression componentwas suggested as: during16mm to35mm of plate thickness, the design strength is330Mpa, and320Mpa between35mm and50mm,310Mpa between50mm and100mm.