Numerical Analysis Of Mechanical Behaviour Of Timber-Concrete Connection With Steel Tube

The timber-concrete structure,originated in the 1950 s,has been widely used since it takes full advantages of timber and concrete.It consists of timber components,concrete components and shear connectors.The shear connectors play an important role in making the wood part and concrete part working together.It alao influences the mechanical properties of the structure directly.Theoritically,steel tube is an effective connection form in timber-concrete structure.Undert this situation,one end of steel tube is embedded in the groove which is reserved in the wooden beam,while the other end is poured together with the concrete board.In this way,the wooden beam is connected with the concrete board through the steel tube.Since the inner and outer surfaces of the steel tube are connected with the wood,the contact area is increased,leading to the bearing capacity and rigidity of the connection improving accordingly.Unfortunately,reaserches on the mechanical properties of steel tube working as a shear connectors is in lackage,which limites the its application in engineering.In order to provide reference for engineers,a three-dimensional finite element model considering the material nonlinear constitutive relation is established in this paper.In the meantime,parameter analysis is carried out by using the numerical model.The main research contents are as follows:? The constitutive relation of timber under complex stress is studied,and the stress-strain updating formula is given.Based on ABAQUS,a nonlinear material model of wood was established,considering the plastic behavior of wood under compression and the brittleness behavior of wood under tension and shear.? A three-dimensional nonlinear finite element model considering material nonlinearity,geometric nonlinearity and contact and friction between different materials is established.The validity of the model is verified by comparing the load-slip curves and failure modes obtained from the single shear tests under parallel and transverse grain loading.Meanwhile the failure mechanism of the joint is analyzed.? The finite element model is used to analyze the material and geometrical parameters,and the formula for calculating the shear stiffness of the steel pipe connection of the wood-concrete composite structure was fitted.? Based on the European Yield Theory,the formulas for calculating the shear bearing capacity under the single shear condition are derived.The influence of steel tube wall thickness,steel tube diameter and timber density on the bearing strength of wood pin groove.The influences of steel tube wall thickness,steel tube diameter and concrete grade on the bearing strength of concrete pin groove were also analyzed with the model.The formulas for calculating the bearing strength of wood and concrete pin slots are fitted.The reliability of the theoretical formula is verified by comparing with the numerical results.