Study On Mechanical Behavior Of Steel-Concrete Considering Nonlinear Constitutive Relation Of Shear Connectors

The effective transfer of shear force on the interface between steel and concrete composite beams are the basis of the interaction between steel and concrete in composite beams.The main component of the transfering of shear force is shear connector,which determines the interface shear strength and shear stiffness.There will be some relative slip at the interface of composite beam under external loads.The more higher the stiffness of shear connectors,the better the combination of the two kinds of materials,the smaller the interface slip value is.The existing researches show that the shear stiffness of the commonly used shear connector is not a constant,and its stiffness decreases with the increase of the load value.The existing analysis of the composite beam interface slip theory,in most cases only considering the shear connector stiffness is constant,that the shear force of the shear connectors is linear with the slip.The study of nonlinear constitutive relation of shear force-slip of shear connectors is far from perfect.In view of this,in order to study the influence of the nonlinear constitutive relation of shear connector on the mechanical behavior of composite beams,the following researches are carried out in the paper:1.Four kinds of typical nonlinear and linear shear connector constitutive curve are puted forward,respectively:nominal linear constitutive,Japanese standard constitutive,square constitutive and Ollgaard constitutive.Baseing on the existing general analysis method and Research results for linear shear connector of steel-concrete composite beams,establish and solve above four kinds of shear connector constitutive composite beam differential equation under mid span concentrated force and uniform load.The corresponding relation between the load and slip of composite beam is obtained.2.With the help of MATLAB,the the development rules of the steel-concrete composite beams with different shear connector constitutive under the condition of concentrated load and uniform load are compared.The influence of shear connector constitutive relation and shear connector spacing on the mechanical behavior of composite beams is analyzed.3.By contrasting the mechanical behavior of composite beam under linear and nonlinear constitutive,two conclusions are obtained.?When the shear bond spacing is less than 300 mm,using the Japanese standard configuration replacing Ollgaard constitutive to calculate interface slip and midspan additional deflection value are feasible under concentrated load.In the calculation of the interfacial shear force,can be using the Japanese standard configuration replacing Ollgaard constitutive.?Under uniform load,using the Japanese standard configuration replacing Ollgaard constitutive to calculate interface slip and are feasible.If the distance between the shear keys is greater than 400 mm,the Ollgaard constitutive can be considered.In the calculation of the interfacial shear force and midspan additional deflection,can be using the Japanese standard configuration replacing Ollgaard constitutive.4.The ANSYS finite element method for the analysis of the steel-concrete composite beams with nonlinear shear connector is presented.The shear connector between concrete slab and steel beam is simulated by combin39 spring element with reasonable definition of D-F curve.The location of the spring element is consistent with the actual distribution of the shear connector.By comparing with the theoretical analysis value of midspan deflection,adopting the finite element analysis model of simply supported composite beam can be used to simulate the deformation of composite beam.