Experimental study of behavior on RPC filled steel tubular stub columns under axial compression

Experiments of 22 RPC filled the steel tubular stub columns subjected to axial compression are carried out. The load versus displacement curves, the failure patterns and the influences of the confinement factor ?and the strength of RPC fc on the ultimate loading capacity have been discussed. The results show that the elastic region of the load versus strain curves is about 90%-95% of the whole, specimens with low confinement factor ?exhibit a rapid softening process in the post-peak region, and a brittle shear failure, while specimens with high confinement factor exhibit a gradual softening process and cause serious bulge in all sections and significant buckling on the top and bottom of the specimen. It is found that high confinement factor and high strength of RPC result in high ultimate loading capacity, the steel tube provides worse confinement to RPC than to the conventional concrete. Equations proposed in this paper agree well with the test results.