The Experimental Research On Flexural Performance Of Timber-Concrete Composite Beams Reinforced By Steel Bar

The timber-concrete composite structure is a new kind of structure in which timber beam is connected with concrete plate by connector.In the composite structure,the concrete is compression and the timber is tension,giving full play to the excellent performance of the two materials.Under the action of load,the deformation of the composite beam is large because of small elastic modulus and natural defects of wood in timber-concrete composite beam.The reinforced timber-concrete composite beam structure can improve the bearing capacity and stiffness.In this paper,the flexural behavior of 4 composite beams are tested.In which,3 composite beams are added to the bottom of the timber beam with rebar of different diameters,and 1 composite beam is not strengthened.The main research contents and results are as follows:1)Drawing up the test plan then making 4 timber beams through theoretical analysis and numerical calculation of finite element method.2)By the flexural static failure test of 4 timber-concrete composite beams.Description and summary of experimental phenomena.The load-deflection curve,the load-strain curve of timber beam bottom and steel bar,the longitudinal strain distribution curve,the longitudinal strain distribution curve of concrete plate in the midspan of timber-concrete composite beams,the interface slip contrast curve of timber-concrete composite beams are obtained.3)The ultimate bearing capacity and flexural rigidity of reinforced of timber-concrete composite beams increased with the increase of rebar diameter.The steel bar is yield when the load reaches about 80%of the ultimate bearing capacity,before this,the strain of the beam bottom and the reinforced bar is kept at the same time,the connection between them is reliable.The neutral axis of the composite beam moves down with the increase of the diameter of the rebar.But there is a unified neutral axis so the cross section deformation of the composite beam satisfies the plane section assumption.4)The theoretical analysis and measured values agree well at the elastic deformation and initial stage of plastic deformation,and the numerical values coincide with the measured values.