Abstract
Mechanical behavior of concrete filled circular steel tubes with extremely thin walled tubes over the domestic limited ratio of diameter to thickness: D/t under centric compression was examined experimentally, with an economical view of application to the bridge columns. Twelve specimens ware prepared, where selected test parameters were D/t and concrete strength. As a result, their strengths attained to the estimation values considering confinement effect of concrete beyond the simple accumulative strengths, if sufficient countermeasures were executed from the tube manufacturing to filled concrete placement stage. Furthermore, the observed failure modes were a diagonal slip of core concrete with an elephant foot like buckling at the end of the tubes.
