STUDY OF BEARING CAPACITY AND COMPLETE STRESS-STAIN CURVES FOR CONCRETE FILLED SQUARE STEEL TUBE COLUMNS

Based on data from 266 tests of concrete filled steel tubular stub columns gathered from literature, the design equations for axial load capacities according to domestic and international codes and specifications are examined. It is found that the equations of AISC, CECS and AIJ specifications are most conservative. The EC specifications provide statistically closer but slightly conservative predictions to the test results. The average predictions by DL and GJB specifications are slightly higher than the test data. The paper also characterizes the load-deformation relationships, and statistically evaluates several stress-strain models proposed by different researchers. It was found that they coincided with test results in the elastic stage, but for the description of the decline and strengthening stages, each model is quite different and has different applicable scope.