Study On Mechanical Behavior Of Thin Walled H Type Steel-wood Composite Beam Connection Interface

Wood structure has been favored by people because of its many advantages such as environmental protection,energy saving,heat preservation,and light beauty.As a renewable building material,wood has the characteristics of light weight,high strength,good seismic performance and easy processing.However,the design strength of wood is low and the strength is degraded with time.The mechanical properties are greatly affected by creep and cracks are easy to occur.Affected by environmental impacts such as corrosion and insect damage.Thin-walled steel is characterized by“saving amount,light weight,flexible molding method and large cross section”.However,as the width-to-thickness ratio of thin-walled steel increases,it is prone to overall instability or local bending,which causes the structural geometry to be abruptly changed.It completely loses its carrying capacity.In order to give full play to the mechanical properties of wood and thin-walled steel,many scholars have been working in recent years to combine thin-walled steel and wood to form thin-walled H-beam-wood composite beams.Related studies have shown that the joint performance of steel-wood composite interface is one of the important factors affecting the bearing capacity of thin-walled steel-wood composite beams is that the interface failure process and failure mechanism and related mechanical properties are still unclear.Therefore,the thin-walled H-beam-wood composite beams proposed by the research group are proposed.Based on the relevant research,the research on the force performance of the relevant combined connection interface is carried out.The work of this paper is mainly carried out through the following four parts:(1)Mechanical properties test of thin-walled H-beam-wood composite beam materials:including moisture content and density of wood,compressive strength of grain,tensile strength of tensile strength,flexural modulus,flexural strength,axial tensile force The Poisson's ratio(scissor)under the action,and other relevant parameters of the wood are derived according to the calculation of the Wood Structure Manual,providing data basis for subsequent theoretical derivation and numerical simulation,as well as the ultimate tensile strength,yield strength and elasticity of the steel.Modulus,Poisson's ratio.(2)Thin-walled H-beam-wood composite beam combined connection interface extrusion test(simple screw connection,simple glue connection,screw and viscose joint):through 6 sets of simple screw connection interface,test,observe and analyze steelwood The yield mode and failure mode of the screw connection,and analyze the inf-luence of the screw material,screw diameter and screw spacing on the interface bea-ring capacity.The effects of flange width and viscose length on interfacial connectio-n performance were investigated by four sets of simple structural adhesive joint tests.The effects of screw spacing and viscose length,combined section width and flange wood thickness on the interface bearing capacity were investigated by 7 sets of screw+adhesive joint test.(3)Derivation of calculation formula of interface bearing capacity: By simplifying the mechanical force model and mechanical analysis,the normal stress differential equation of flange wood is derived,and the relationship between normal stress and interface shear stress of flange wood is established.And the calculated flange strain of the flange is used to calculate the normal stress calculation formula of the flange wood,and the calculation formula of the shear stress of the steel-wood interface is established.Based on this,the calculation formula of the bearing capacity of the steel-wood composite interface is derived.(4)Numerical simulation analysis of the connection interface: The finite element analysis of the test model was carried out by ABAQUS software,and the effective material property definitions of wood,steel,screws and other materials were carried out,and the unit mesh division and interface interaction were systematically studied.The numerical simulation results of the steel-wood composite interface are compared with the experimental results to verify the validity of the simulation.On this basis,the parameters of the steel-wood composite interface are analyzed,considering the thickness and strength of the thin-walled H-shaped steel,and the self-tapping screws.The influence of length,strength,etc.on the interface bearing capacity.The research shows that the bearing capacity of the combined joint interface is related to the screw material,screw diameter,screw spacing,flange wood width,viscose length,flange wood thickness and other factors.The simple screw connection and the simple glue connection interface show brittle failure,and the screw + viscose hybrid connection not only effectively improves the bearing capacity of the interface,but also has the characteristics of continuous damage.Through theoretical calculation and analysis,a strength reduction factor of 0.87 is proposed.Comparing the experimental value with the theoretical calculation value,the calculation error is about 4%.The simulation study shows that the numerical simulation results of the steel-wood composite interface are in good agreement with the experimental results,thus verifying the validity of the simulation.The research results provide a reference for further research on the mechanical mechanism and flexural capacity of the built-in thin-walled H-beam-wood composite beam.It is of great significance to develop a new high-performance green environmental protection combined structure,promote the assembly and industrialization of building structures,achieve green construction,and ultimately achieve energy conservation and ecological balance.