Flexural behavior and reliability analysis of rectangular concrete-filled cold-formed steel tabular beams

Abstract

Concrete-filled steel tube (CFST) has been widely investigated for columns, whereas it has been less explored for beams. This study investigates the behavior and reliability of CFST beams under bending, both experimentally and theoretically. Experiments were performed on nine rectangular CFST beams and three steel tube (ST) beams under bending. The experimental results showed that local buckling was the failure of both ST and CFST beams. The load−deflection behavior of CFST beams was significantly better than that of ST beams. Load-carrying capacity and stiffness of CFST beams was found to be approximately 3.0 and 1.29 times those of ST beams, respectively. The mechanical properties of steel were much more efficiently exploited in CFST beams than in ST beams. The mean ductility of 8.19 classified CFST beams to be highly ductile. The average plastic hinge length approximately equals the height of CFST beams. An available model was used to predict the moment capacity of CFST beams, and the results confirmed the accuracy of the model. Results of reliability analyses showed that mean moment capacity was independent on any individual variable or a combination of variables. In contrast, the standard deviations heavily depended on the considered variables. Consequently, the reliability index due to variable of steel thickness is the highest at 32.2, followed that due to the steel strength at 24.5, whereas those due to other variables varied from 8.0 to 9.3.