Experimental and numerical study on the effect of parameters in axial capacity of CFST columns with various L/D ratios

Strength as well as behaviour of 16 circular concrete filled steel tube (CFST) sections submitted to axial compressive load was presented in this paper. Specimens having length to diameter (L/D) ratios of 3, 4, 5 and 6 with diameter to thickness (D/t) ratios of 38 as well as 25.33 with same outer diameter of 76 mm and two different wall thickness of 2 mm and 3 mm were considered to study the influence of column parameters and effect of confinement (Ꝣ). The ultimate capacities of CFST columns were compared with Eurocode-4, Australian Standards (AS 5100), American Code (AISC 360 - 10) and Chinese code (DBJ13-51) predictions. Results showed that axial compressive loads of specimens with more wall thickness were found to be greater than lesser wall thickness specimens. The parameters that affect the column behaviour directly are relative slenderness ratio (λ) and L/D. Eurocode-4 results found to be conservative, Australian code and American Code underestimated while Chinese code overestimated the section capacity. Further, a finite element model of CFST specimens was developed with ABAQUS to check the accuracy of test results, buckling patterns and displacement curves.