Experimental and theoretical study on rectangular concrete filled steel tube columns subjected to axial compression

Experimental work on sixteen Rectangular Concrete Filled Steel Tube (RCFST) stub columns subjected to axial compressive load are presented in this paper. The main objective of this study is to determine the effect of thickness and Length to Breadth (L/B) ratio on the strength and behavior of RCFST columns. Specimens with L/B ratio of 3, 4, 5 and 6 having Breadth (B) x Depth (D) x thickness (t) of 76 x 25 x 2 mm and 76 x 40 x 3 mm are considered for this study. The infill material used in this RCFST specimen is self-compacting concrete (SCC) with M30 grade. Failure modes, axial load - deformation behavior and ultimate axial capacities along with parameters like confinement (xi) and strength index (SI) are studied and compared with 2 mm and 3 mm thick specimens. The ultimate axial load values obtained from the experiments (N-e) are compared with design values (N-c) predicted from codes like Eurocode - 4 (EC-4), Australian code (AS5100), Chinese code (DBJ13-51) and American Concrete Institute (ACI - 318). Results showed that, specimens with greater thickness and smaller L/B carried higher axial compressive load. Predicted load values of EC4 showed conservative results while the remaining codes showed un-conservative in predicting the results. At-last, an analytical expression is proposed to determine the axial compressive load and the predictions are near to accuracy of experimental results. Copyright (C) 2022 Elsevier Ltd. All rights reserved.