Experimental study on rectangular CFT columns with high-strength concrete

摘要

In the 1999 AISC-LRFD, the in-filled concrete strength (f'_c) of concrete-filled tube (CFT) columns is limited to a maximum value of 55 MPa (N/mm~2). That limiting value is raised to 70 MPa in the 2005 AISC-LRFD. This study aims to assess if the LRFD CFT column formulas are applicable to intermediate to long rectangular columns with higher concrete strengths. Twenty four specimens with f'_c varying between 29 and 84 MPa were tested. Various formulas and relevant provisions for CFT columns as specified in the major design codes including AISC-LRFD, EC 4, AS-5100, and CSA S16-01 were examined and compared. The design CFT strength (P_u) predicted by the AISC-LRFD formulas and the test results (P_(test)) were found to be in good agreement. The higher f'_c limiting value of 70 MPa proposed in the 2005 AISC-LRFD appears acceptable. The test results reveal that the 1999 AISC-LRFD design strengths are conservative and tend to penalize these CFT columns with higher concrete strength.