Modified confining stress path dependent analytical model for axially loaded circular normal, high and ultra-high strength concrete-filled steel tube stub columns

Previous studies suggested that the behaviors of confined concrete in concrete-filled steel tube (CFT) columns were dependent on their confining stress paths, which thus should be considered in order to well predict their behaviors. Several confining stress path dependent analytical models had been proposed, which, however, were all developed for fiber polymer (FRP) confined concretes. Although one of the existing models can also be applicable to CFT columns, it mainly focused on the specimens with normal strength concrete. Additionally, existing confining stress path dependent models may result in fluctuation issue of load-deflection curves for CFT specimens. This paper proposed a new confining stress path dependent analytical model that is applicable to normal, high and ultra-high strength concrete-filled steel tube columns. Experimental tests were collected to assess the performance of the proposed analytical model, and it was found that the proposed model performs quite well for normal, high and ultra-high strength concrete-filled steel tube columns and generally can avoid the fluctuation issue of load-deflection curves.