Study On Bending Behavior Of Cold Formed Thin-Wall Rectangular Section Steel-Timber Composite Beam

With the national attention to ecological civilization and energy conservation and emission reduction goals,more and more attention is paid to environmentally friendly buildings.The steel has high strength,good ductility and high assembling degree,but because of the small cross-section size and thin steel plate,it is easy to lose overall or local stability and lead to the decline of bearing capacity.Timber is a natural and renewable material with low energy consumption,low environmental pollution and recycling,but timber structure is easy to be brittle failure due to fiber being pulled.Steel-timber composite structure,with the advantages of steel and timber structure,is the combination of steel and timber with a certain combination of the structure,can maximize the performance of their own materials,make up for their own shortcomings.This paper presents two new types of cold formed thin-wall rectangular steel-timber composite beams.In order to study the flexural behavior of composite beams,5 test beams were tested.The combined effect of steel and timber was studied by comparing the yield load and ultimate bearing capacity The effect of different combination methods of timber and selftapping screw connection on the flexural performance of composite beams.The main research contents and results of this paper are as follows:(1)The bending properties of cold formed thin-wall steel sections can be significantly improved by epoxy AB glue and tapping screw connection compared with steel beam,the yield load and ultimate load of composite beam with inner timber-filled square are increased by 104.09%and 96.79%,and the yield load and ultimate load of composite beam with outer timber-filled square are increased by 135.68%and 162.55%,At the same time,in the bending process of the two materials combined well,can play their own good performance.(2)Under the limit condition of approximately the same section area of timber,the flexural performance of the composite beam with outer board is better than that of the composite beam with inner backfill,the yield load and ultimate load of the composite beams are increased by 15.48%and 33.42%,respectively,and the failure modes of the two types of composite beams are different,the failure mode of the composite beam with outer board is that the timber is pulled out in the bending-shear zone,and the failure mode of the square composite beam with inner packing is local buckling in the compression zone near the loading point.(3)Drilling tapping screws has no significant effect on the flexural behavior of the composite beams with inner backfill,the yield load and ultimate load of the epoxy AB+selftapping screw-bonded epoxy are 11.84%and 3.44%lower than those of the AB-bonded composite beams,respectively.(4)Using Abaqus finite element software to carry on the numerical simulation to the composite beam,compares the simulation value and the test result,discovered that both agree well,verified the validity of the model,by adjusting the parameter in Abaqus model,carries on the parameter analysis,the influence factors of flexural performance of composite beams are investigated.The results show that the flexural performance of composite beams can be improved by increasing the thickness of flange board,section steel wall and yield strength in a certain range.(5)The theoretical calculation of steel-timber composite beam is designed by using the formula of steel reinforced concrete composite beam for reference.