Research On Capacity Of Steel-concrete Composite Structure Under In-plane Forces And Out-of-plane Moments

Steel-concrete composite(SC)structure is widely used in construction of offshore structures,nuclear facilities and high-rise buildings due to its better lateral resistance and seismic performance compared with conventional RC structure.SC structure are normally constructed using steel faceplates,infill concrete and connectors.Through-thickness tie bars and headed shear studs are used to anchor the steel faceplates to the infill concrete.At present,large majority of theoretical analyses and experimental research has been conducted on the in-plane mechanical behavior of SC structures.However,there are relatively few studies on the capacity of SC elements subjected to in-plane membrane forces combined with out-of-plane moments.Failure of SC element is defined due to the yielding of steel plates.Therefore,the capacity of SC element under in-plane forces and out-of-plane moments could be explored by small-deflection plate theory.The interaction curves of Nx-Ny,Nx-Mx,Ny-Mx,Mx-My and the interaction surfaces of Nx-Ny-Vxy,Nx-Ny-Txy,Nx-Ny-Mx,Nx-Mx-My are obtained and compared under different criteria of steel plate.Improved equivalent methods for out-of-plane bending moment and torsion are proposed based on the Code(ANSI/AISC N690s1-15).The methods can be written as an effective arm length ratio expression,which is related to in-plane forces,reinforcement ratio and elastic modulus of materials.Over 960,000 examples of different load combinations are calculated.The results indicate the expression' conservatism.Overall,this paper investigates the performance of SC structure subjected to combined in-plane forces and out-of-plane moments with consideration of biaxial loading effects and Poisson's ratio of materials.Furthermore,design approach proposed for converting bending moments and torsion provides reference for the design of SC structure under combined loads.