Shear response of concrete filled tubes part II: Analytical study

Concrete-filled steel tubes (CFSTs) and reinforced CFSTs (RCFSTs) are used as bridge piers or as piles or shafts for deep foundations. Prior research shows that the flexural strength and stiffness capacities of these composite members exceed those of structural steel and reinforced concrete components with similar diameter and material quantities. Recent research has experimentally evaluated the impact of design parameters on the shear strength of CFSTs or RCFSTs, including geometry, reinforcement, material strengths, and bond (tube-concrete interface) conditions. Using that work as a basis for understanding and model validation, the study was expanded using an analytical parameter study. High resolution nonlinear finite element models were developed with the ABAQUS computer program [3, 4]. The resistance and nonlinear behavior from the nonlinear analyses were compared to the experimental results to verify the accuracy of the nonlinear computations. The past experiments were limited in the range of tube diameters, axial load ratios and internal reinforcement ratios. Therefore, the analytical models were used to conduct parameter studies to study the effects these parameters on CFST and RCFST behavior and strength. The results of these calculations are combined with the experimental results to develop improved predictions of CFST and RCFST resistance in equations suitable for design.