Experimental Study And Theoretical Analysis On The Stiffness Of Steel-plate Concrete Structure Panel For Nuclear Facilities

Steel-plate concrete(SC)structure refers to a kind of composite structure that are reinforced with steel faceplates using shear connectors and steel ties.SC structure adopts modular prefabricated construction technique and features efficient mechanical property and rapid construction,which is widespread use in nuclear facilities,off-shore structures and high-rise buildings.The experimental study and theoretical analyisis on the stiffness of SC panel is conducted.The effective stiffness of SC panel is vital in estimating the deformation characteristic of SC structures according to the feasibility study on the design method based on SC panel.And the effective stiffness is under the influence of the ratio and the numerical value of the biaxial loads.An experimental study of nine SC panels subjected to biaxial tension and compression was conducted in order to establish the stiffness model of SC panel.The test parameters include the ratio of compression to tension and the thickness of steel-plate.The experiment results showed SC panels feature excellent ductility and typical orthotropic mechanical properties.The compressive modulus,tensile modulus and Poisson effects are all under influence of the ratio and the value of biaxial stresses when the SC panel are treated as a smeared material.A stiffness model based on isotropic linear elastic material is proposed for the purpose of preliminary design of SC structures.The model suggests that the effective stiffness should be determined according to the state of SC panel in the principal force space and be benchmarked by the effective elastic parameters of SC panel subjected to uniaxial tension,in-plane shear and uniaxial compression.The computational formulas of effective elastic modulus and effective Poisson ratio are presented,which have considered the effects of steel-plate ratio and the material characteristic of concrete and steel.Another stiffness model based on biaxial orthotropic elastic material is proposed for the purposed of accurate analysis of stress redistribution in SC panel.The computational formulars of compressive modulus,tensile modulus and biaxial Poisson ratio of concrete are presented.The basic and important material coeffients are benchmarked by the biaxial tension and compression experiments of SC panel.The model is able to show the compression softening of concrete and the unique phenomenon of concrete stress from positive to negative in the direction of tensile loading.The two stiffness model of SC panel are both compared with the analysis of FEM numerical computation and the experiments of SC panel.The theoretical results approach to the experimental results very well.The accuracy and feasibility of the two stiffness model are verified.