Flexural Behavior of High-Strength Rectangular Concrete-Filled Steel Tube Members

Abstract

This study experimentally and numerically investigates the flexural behavior of high-strength rectangular concrete-filled steel tube (CFST) members. An experimental database including 30 flexural tests on high-strength rectangular CFST members was compiled, and gaps in the existing research were identified. To address these gaps, a total of 14 specimens were tested, considering the effect of tube thickness, compressive strength of concrete, yield stress of steel, and tube height. Detailed finite-element models were also developed and benchmarked for parametric studies. Results from the tests and finite-element analyses indicated the following: (1) the flexural strength increased with the increasing tube thickness, yield stress of steel, tube height, and tube width, while the effect of the compressive strength of concrete was minor; (2) the flexural stiffness increased with the increasing tube thickness, tube height, and tube width, while the effect of the yield stress of steel and compressive strength of concrete was minor; and (3) high-strength CFST members, especially those with high-strength steel tubes, had lower ductility compared with conventional-strength CFST members. Experimental and numerical results were also used to evaluate the applicability of current design provisions (i.e., AISC 360-16, GB 50936-2014, Eurocode 4, and the AIJ) for estimating the flexural strength and stiffness. The evaluation showed that AISC 360-16 reasonably estimated the flexural strength, while AIJ provided the most accurate estimation of the service-level flexural stiffness.