Design Method And Overall Buckling Behaviour Of Q460 High Strength Steel Welded I-section Simply-supported Beams

With the gradual improvement of produaction technology of steel,high strength steel which yield strength greater than or equal to 460MPa is widely used in domestic and foreign building structures.High strength steel in material mechanics performance,influencing of the production process,as well as the initial defects has obvious difference with ordinary strength steel,the overall stability performance are also different.However,the design formulas of steel components concerned in the current design specifications in domestic and foreign are formulated based on the test and theoretical research of Q235 and Q345 ordinary strength steel components,and there is a lack of mature calculation theory and design method for the mechanical properties of high strength steel components.In this paper,the overall stability of simply supported beam of Q460 high strength steel is studied by the method of finite element analysis and experimental research.The basic contents and results of research are as follows:Three types of welded I-section of Q460 high strength steel residual stresses were measured by cross section method,,and the distribution law of residual stresses of double-axial symmetry,upper flange strengthening and lower flange strengthening I-section was obtained.The overall stability of 10 welded I-section simply supported beams of Q460 high strength steel was tested.Top flange is significantly higher than the overall stability of bearing capacity for reinforced I-section beam bottom flange reinforced,enhanced overall stability bearing capacity of single axisymmetric I-section beam above the biaxial symmetry model,to strengthen the flange width can obviously improve the integral stability bearing capacity of steel beams.ANSYS finite element program was used to simulate the test.The instability failure mode,overall stability bearing capacity and mid-span load-displacement curve of the specimens obtained by finite element analysis were in good agreement with the test results,which verified the accuracy and reliability of the finite element model.On this basis,a large number of finite element parameter analysis on the overall stability of simply supported beams of welded I-section of Q460 high strength steel was carried out by transforming the section aspect ratio and regularized length-thin ratio of members,and the overall stability bearing capacity of members was obtained based on the influence parameters.Compared the test with finite element calculation results and the national standard,the results show that the steel structure design codes in China(GB50017-2017)and American standard(ANSI/AISC360-2016)to calculate the overall stability bearing capacity of high strength steel welded I-section beam Q460 is unsafe,European specification(Eurocode3-2005)of the calculation results are more conservative,high strength steel structure desion codes in China(draft)(JGJX-201X)the calculation result is the closest and is safe.Based on the calculation formula of the overall stability bearing capacity of the bending member in JGJX-201X,the calculation curve of the overall stability bearing capacity was fitted again,and a design method for the overall stability bearing capacity of the welded I-section beam of Q460 high strength steel was proposed.