Experimental Study And Theoretical Analysis Of Axial Compression Members With Single-limb Fire-curved Equal-edge Double Angle Steel

The single-limb fire-curved equal-edge double-angle steel member is a new type of double-angle steel connection member,which is composed of straight equal-edge angle steel and fire-curved equal-edge angle steel.By bending one of the equal-angle steel members,the distance between the two limbs can be reduced,so that the thickness of the filling plate can be reduced,so as to achieve the goal of reducing the amount of steel used and not significantly affecting the load-bearing performance.In this paper,experimental study,finite element numerical simulation and theoretical analysis are combined to study the load-bearing performance of single-limb fire-curved equal-edge double-angle steel member.The main research contents are as follows:(1)Axial compression tests were carried out on five groups of single-limb fire-curved equal-edge double-angle steel members.and two groups of ordinary double-angle steel members.The differences of failure modes and load-bearing performance between single-limb fire-curved equal-edge double-angle steel members and ordinary double-angle steel members were studied.The results show that the mechanical mechanism and failure characteristics of each group of three specimens are comparatively consistent(except for individual specimens whose failure modes are different due to the influence of initial defects),the bending deformation of ordinary double-angle steel members occurs around the asymmetric axis,and the bending deformation of single-limb fire-curved equal-edge double-angle steel members occurs around the symmetrical axis.All the specimens entered the yield in midspan,except for the fire section of single limb equal-edge double-angle steel specimens with slenderness ratio of 60 and 80,which entered the yield,the other specimens remained elastic.The bearing capacity of the two types of angle steel members decreases with the increase of slenderness ratio.When the ratio of slenderness to length is 60,the bearing capacity of double-angle steel members decreases by 10.35%,while the ratio of slenderness to length is 140,the influence of single-limb fire on bearing capacity is small,which decreases by 8.08%.(2)Finite element software ABAQUS was used to refine the numerical simulation of the test specimens.The finite element results are in good agreement with the experimental results,which verifies the reliability of the finite element analysis.The influence of initial bending,yield strength of angle steel,thickness of filling plate,bending distance and length of bending section on the load-bearing performance of single-limb equilateral double-angle steel members is analyzed by using finite element software.The results show that the bigger the initial bending is,the lower the bearing capacity is;with the increase of the yield strength of angle steel,the bearing capacity of the component increases gradually;with the increase of the thickness of filling plate,the ability of the two angle steels to work together is enhanced,and the bearing capacity of the component is increased;the length of the fire section and the bending distance of the fire section significantly affect the stiffness of the component,and the bearing capacity of the component decreases with their increase.(3)The test values of bearing capacity of common double angle steel specimens are compared with those calculated by the existing codes Standard for design of steel structures(GB50017-2017)、 Technical regulation of design for tower and pole structures of overhead transmission line(DL/T5154-2012)and Design of latticed steel transmission structures(ASCE10-1997).The results show that the theoretical values and tests of Standard for design of steel structures(GB50017-2017)are presented.The test value is the closest.Therefore,based on the formula for calculating the bearing capacity of ordinary double-angle steel members in the Standard for design of steel structures(GB50017-2017),and combined with the experimental and parameter analysis results,the reduction coefficient of the bearing capacity of single-limb fire-curved equal-edge double-angle steel members under axial compression is given.