Chemical Prestress of Expansive-Concrete-Filled Steel Tube with Flat Bar in Center

Abstract

We study the expansive concrete filled steel tube with a flat bar in center using for a brace member of the energy dissipative braced frame. The test results of the chemical prestress of this tube with a flat bar in center may be summarized as follows : (1) The concrete with Water/ (Cement + Silica fume + Expansive admixture) =25-30% and Ex/ (C+S+Ex) ≥50% has a very high expansive capacity. (2) Ratio of the tangential normal stress to the yield stress of the steel tube at yield of it is about 1.15. (3) Ratio of the axial normal stress of the flat bar to the axial normal stress of the tube at yield of it is 0.15 0.45. (4) Ratio of the axial normal stress to the tangential normal stress of the tube at yield of it is 0.4-0.5.
From the above results, We proposed the estimate formulae for the prestress of the expansive concrete in the tube with a flat bar in center at yield of the tube.