STUDY OF CONCRETE FILLED STEEL TUBE (CFST) BEAMS

Abstract

Concrete-filled steel tubes (CFSTs) are mainly used for piers, columns or as caissons for deep foundations because of their large compressive stiffness and large axial-load carrying capacity. Recently, other structural systems have used CFST members for girders and members subjected to bending. Flexural behavior is the primary design issue for these applications due to lack of understanding of the flexural behavior of CFST. But sometimes only experimental results are not enough to get the full insight of behavior of a member. Complementary advanced numerical models are needed to simulate the flexural behavior of CFST to extend the experimental research and develop predictive tools required for design and evaluation of structural systems. In this study, a finite element model for CFST subjected to bending was developed. The conduct of composite action of CFST beam is predicted by the proposed finite element model and verified by comparing with test results. The model was used to conduct a series of parametric studies to study the impact of the materials properties and steel tube plate thickness ratio. Enhancement in moment capacity of CFST is noted for a particular range of thickness ratio. The results thus obtained can be used to optimize the CFST members and use it to its maximum capacity.