Axial compression tests on centrifugal concrete filled steel tubular short column specimens were carried out by authors. The concrete is cast by centrifugal spining method using super high strength concrete, and the concrete portion of section has a vacant hole. From the results of experiments, we confirm that experimental maximum strength is higher than superposed strength, even if a section has the vacant hole. Especially, in case of a circular section, concrete filled steel tublular columns has confining effect on filled-concrete by steel tube. In this paper, the evaluation formula of compression strength of consideration for confining effect derived from the results of the axial compression tests. Ultimate compressive strength of concrete filled steel tubular circular columns can be estimated by proposed fomula.
