Shear response of steel fiber reinforced recycled concrete-filled steel tube columns

A comprehensive study of the shear characteristics of steel fiber reinforced recycled concrete-filled steel tube (SRCFST) columns is conducted. 50 CFST stub columns are tested with the variables of steel tube diameter-thickness ratio (D/t), shear span-to-depth ratio (lambda), axial compression ratio (n), and concrete mix. Two types of cements, three recycled aggregate percentages, three water-cement ratios, and three steel fiber contents are considered in design of concrete mixes. The experimental results show that SRCFST columns present the coincident shear behavior of the ordinary CFST columns. As lambda is increased, shear resistance shows a downtrend, while the flexural strength presents an increasing trend. Imposing axial compression or thickening steel tube contributes to an adequate safety margin in plastic period. Based on the contributions superposition method, a predicted model of the shear capacity of SRCFST columns is proposed in consideration of shear-span ratio, axial compression, and self-stress.

Automated summary

The study found that SRCFST columns exhibit similar shear behavior to ordinary CFST columns, with shear resistance decreasing as the shear span ratio increases and flexural strength showing an increasing trend. Applying axial compression or thickening the steel tube can provide an adequate safety margin during the plastic period.