Local Buckling Behaviour And Design Method Of 6082-T6 Aluminum Alloy I-Section Beams

Compared with the traditional type of aluminum alloy,6082-T6 aluminum alloy is more excellent in strength,welding performance and corrosion resistance,and has a good application prospect in the field of engineering structure.Aluminum alloy I-beam is a common component in engineering,but the elastic modulus of aluminum alloy is low,and the local stability of the structure caused by large deformation affects its use.Therefore,it is of great practical significance to study the local stability of aluminum alloy I-beam.In view of the lack of research on the local stability performance and design method of 6082-T6 aluminum alloy I-beams,this paper combines finite element analysis and local buckling stress mechanism analysis.From the perspective of bearing capacity limit state,a series of studies were carried out on the local stability performance of 6082-T6 aluminum alloy I-beams under bending and shear and local pressure.The main research contents and achievements of this paper include:（1）The ultimate load and post-buckling behavior of the members were obtained by finite element modeling using eigenvalue buckling analysis and nonlinear buckling analysis.Using the validated finite element model,69 I-beam models were established for finite element parameter analysis to study the influence of different parameters on the local stability of I-beam under bending and shear.When the amplitude of the local geometric initial defect of the web changes,the variation of the shear capacity is within 5%;increasing the thickness of the flange,the maximum increase in shear capacity is 7.4%.By reducing the width-height ratio of the web,the maximum increase in shear capacity is 30.5%;when the width-height ratio of the web is small,the anchoring constraint effect of the head rib on the web tension band is more obvious,which can effectively improve the shear capacity of the specimen.（2）Through the analysis of the local buckling mechanism of aluminum alloy I-beams under bending and shear and the comprehensive consideration of the advantages and disadvantages of various calculation methods of shear capacity,based on the calculation method of web shear capacity in the European code for aluminum alloy EC9 and the improved rotation stress field method proposed by Shi Yongjiu,and considering the parameters affecting the local stability bearing capacity,the calculation formula of shear capacity suitable for 6082-T6aluminum alloy I-beams is proposed.The maximum error is within 5%,which verifies the accuracy of the proposed formula.Combining the calculation method of shear bearing capacity proposed in this paper,the calculation method of effective flexural bearing capacity proposed by Wang Yuanqing and the calculation form of bending-shear related stability bearing capacity in EC9,the proposed formula of bending-shear related stability bearing capacity for 6082-T6aluminum alloy I-beam is proposed.Compared with the original calculation method,the bearing capacity of the proposed formula is increased by 11%,and the discreteness of the calculation results is also improved.The proposed formula is feasible.（3）Using the validated finite element model of I-beam under local pressure,53 I-beam models were established to study the influence of different parameters on the ultimate bearing capacity of aluminum alloy beam web after buckling under local pressure.When the initial defect amplitude of the web geometry changes,the ultimate bearing capacity changes within 3%;with the increase of flange width-thickness ratio,the maximum reduction of ultimate bearing capacity is 13%.When the height-thickness ratio of the web changes,the maximum change of the ultimate bearing capacity is 3.8%.With the increase of flange thickness,the maximum increase of ultimate bearing capacity is 15.6%.（4）Through the comparison of the existing methods and the analysis of the local buckling mechanism of I-beams under local pressure,based on the calculation method of Zhen Shengwei,and considering the factors affecting the ultimate bearing capacity of I-beams under local pressure,the proposed formula for the ultimate bearing capacity of 6082-T6 aluminum alloy I-beams under local pressure is proposed.The ratio of P_FE（T）/P_D the ultimate bearing capacity finite element results（test results）to the calculation results of the modified formula in this paper is 1.25,and the standard deviation is 0.17,indicating that the modified formula is feasible.