BEHAVIOR OF CIRCULAR TUBED REINFORCED CONCRETE STUB COLUMNS UNDER AXIAL COMPRESSION

The behavior of 20 circular tubed reinforced concrete (CTRC) columns was investigated experimentally under static axial compression. The parameters in the study include the diameter-to-thickness ratio of the steel tube, the compressive strength of concrete (C80 and C50) and grade of the steel tube (Q235 and Q345). The test results indicate that the height of separated tubes in a CTRC column affects little on the axial load strength and ductility of CTRC stub columns. The ductility of CTRC columns decreases as the diameter-to-thickness ratio and the increase of concrete compression strength. The axial load strength of CTRC columns increases as the yield strength of the steel tube increases, while the yield strength of the steel tube affects little on the ductility of CTRC columns. The results of the elastic-plastic analysis on the steel tube indicate that the steel yields at the peak load point. A design equation to calculate the axial load strength of CTRC stub columns as well as design advices was proposed.