Theoretic Analysis for Composite Elastic Modulus of Concrete-filled Rectangular Steel Tube Member

Considering the hooping effect between steel tube and core concrete, established a small-deformation elastic analysis theory for the concrete-filled rectangle steel tube (CFRST) member, founded the elastic constitutive relations of CFRST, and accomplished the semi-analytical and semi-numerical solution of the composite elastic modulus. Research shows: composite elastic modulus of CFRST is higher than conversion elastic modulus without considering the hooping effect. Within certain value range of parameters, composite elastic modulus is 1.36% - 15.3% higher than conversion elastic modulus. Further more, as the steel ratio increases, the composite elastic modulus increases significantly, but the sensitivity of the composite elastic modulus to the strength of concrete is small.