| Steel structure has been widely applied in construction projects because of good performance, such as light weight, high strength, better plasticity and toughness, uniform texture, good seal and convenient construction. With the continuous emergence of super high-rise and large-span steel structures,high performance structural steel named GJ structural steel with great seismic behavior, good weldability and excellent impact ductility has been developed and used in many large scale projects, such as New CCTV Headquarter Building, National Olympic Stadium and Resorts World Sentosa etc. However, it could be found that the researches on the structural performance of GJ structural steel members were quite limited. At the same time, the study on design parameters is in the initial stage which have not been listed in the specifications. Consequently, in order to promote the application of GJ structural steel, it is necessary to study the structural behavior of GJ structural steel.Supported by the National Natural Science Foundation of China(NO.51578089), experimental and design parameters studies on lateral torsional buckling behavior of welded Q460 GJ structural steel H-shaped beams have been carried out. The main contents of the paper are summarized as follows:(1)Theory: The difference between the overall stability design methods in specifications from China, America and Europe have been discussed. Structural reliability theory was used to solve the partial factor of material resistance and check the reliability index of structural members.(2)Experimental study: Eight doubly symmetric welded H-shaped beams, which were laterally restrained at the mid-span, have been tested. And two cross sections(H270×180×8×10 and H450×180×8×10) and four kind of lengths(5m,6 m, 7 m, 8 m) were designed. The load versus the displacements curves, the load versus the strain curves and limit load of the tested beam have been obtained and these results have been compared with buckling strength from China, America and Europe specifications.(3) Numerical analysis: Finite element analysis(FEA) models considering initial geometric imperfection and measured residual stresses were established and verified by comparing the experimental results with the FEA results. By using the validated FEA models, parametric studies were carried out as well. The data obtained from parametric studies were used as the statistical parameters of the resistance and compared with the design buckling curves from China, America and Europe specifications.(4)Reliability study: Firstly, the parameters of the material property uncertainties of Q460 GJ structural steel could be obtained according to the statistic of the yield strength. Secondly, based on the comparative analysis of the test results and FEA results with buckling strength from Chinese steel specifications, the parameters of the resistance model uncertainties of Q460 GJ structural steel could be calculated. Thirdly, the parameters of the resistance uncertainties of Q460 GJ structural steel could be calculated by using the parameters of the material property uncertainties, the resistance model uncertainties and the geometric quantities uncertainties. By using these parameters, the partial factors for resistance of Q460 GJ structural steel could be recommended. Meanwhile, the structural reliability will be verified according to the recommended partial factors for resistance. Finally, the design parameters of Q460 GJ structural steel have been suggested. |
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