On The Study Of Negative Moment Area Of New Type Steel-encased Concrete Composite Beams

New type of steel-encased concrete composite beams is a structure provided with high load capacity,high stiffness and vibrate resistance,which combines with the compressive property of reinforced concrete beams and tensile property of steel beam.These advantages of new type of steel-encased concrete composite beam makes it possible to obtained well structure performance by applying simple construction technology and traditional construction method,and has broad application prospects.This paper presents the bending resistance of the composite beams by the plastic theory and papooses a method for solving ultimate bending capacity of a new type of steel encased concrete composite beams under negative bending moment,which bases on Code for Design of Steel Structures and its previous experimental research.The results of this method are in good agreement with the experimental results.The paper uses the finite element software ABAQUS6.12 to model nonlinearly simulate composite beams and selects the appropriate material unit with the consideration of the interface relative slip between steel beams and concrete beams.Comparing finite element simulation results and the existing experimental results,this thesis concludes that the new type of steel-encased concrete composite beams model is reasonable.Based on finite element model,this thesis intends to analyze the mechanical properties of composite beams under negative bending moment and investigate the effect of concrete strength grade,anti shear connection piece space,steel yield strength and plate thickness on mechanical behavior of composite beams under negative bending momentOn the base of finite element analyses and explain and relative slip theory,this paper puts forward the differential equation of relative slip of new steel encased concrete composite beam.Taking into account the slip factor of beam deflection change combination,this thesis compares the existing test results and the finite element model,and concludes that the solution method is in agreement with the experimental results and the finite element simulation results according to a combination of differential equation of sliding beam calculated slip deformation caused by the additional deflection.