Numerical Simulation Research On Mechanical Behavior Of Precast Steel-concrete Composite Panels

In prefabricated concrete structures,the floor slab is generally in the form of reinforced concrete composite slab,which is composed of prefabricated slab made by factories and post-poured concrete layer from the construction site.Prefabricated slab is the key to determine the performance of composite slab.The prefabricated slab with reasonable structure has good mechanical performance,high production efficiency,convenient transportation and stacking,simple and convenient site construction and strong integrity of the composite plate formed by pouring,etc.Therefore,a new type of precast steel-concrete composite panel(hereinafter referred to as composite panel)is proposed.In this paper,the composite panel is designed,and its mechanical properties are systematically studied based on numerical simulation and theoretical analysis.Based on ABAQUS finite element analysis,the mechanical performance of composite bottom plate is studied.The crack development of composite panel,failure characteristics are studied,and the key mechanical properties such as elastic flexural stiffness,cracking load and ultimate load under uniform load are obtained.The engineering applicability of composite panel is analyzed,and it is verified that the composite panel can be constructed without support,and the bearing capacity,deflection,crack control and crack resistance of composite panel meet the requirements of the code.The shear stress of web of the connectors is studied.The relationship between the shear stress of web of the connectors and the load is approximately linear.The shear stress of web of the connectors near the end of the slab is larger.The influence of parameters,including the width of the upper plate,the thickness of the upper plate,the layout of connectors,the distance between the connectors,the length of the connectors and the thickness of steel plate for fabricating the connectors,on the mechanical performance of the composite panel are analyzed.The sensitivity analysis of the parameters that affect the mechanical performance of the composite panel is carried out,and the influence degree of each parameter on the mechanical performance of the composite panel are obtained and the importance are sorted.At the same time,the interaction value of each parameter is calculated.It is found that the thickness of the upper plate and the distance between the connectors are the main controlling factors of the mechanical properties of the combined composite panel.Increasing the thickness of the upper plate and decreasing the distance between the connectors can greatly improve the mechanical properties of the combined composite panel.The interaction between the parameters of upper plate width is small,which can affect the mechanical performance of composite panel independently.The elastic flexural stiffness,web shear stress of connectors,cracking load and ultimate load of composite panel are analyzed theoretically.Through analysis,it is found that the shear deflection of composite panel under uniform load cannot be ignored,so it is suggested to multiply the equivalent flexural stiffness by a reduction coefficient of 0.74 as the short-term stiffness of composite panel.At the same time,it is found that the distribution of compressive stress in different sections of the upper plate is different when the combined bottom plate is in the ultimate state of bearing capacity.Based on this,the "balance method" for calculating the shear stress of the web of connectors is improved.The calculated values of shear stress,cracking load and ultimate load are in good agreement with the simulated results.