Shear Strength of Reinforced Concrete Columns Strengthened with Carbon-Fiber-Reinforced Plastic Sheet

TLDR

The study proposes a simple superposition method using a shear coefficient to estimate the shear strength of RC columns strengthened with CFRP sheets. Seven RC columns wrapped in CFRP were tested under cyclic lateral loading with constant axial load, varying sheet amount, shear span/depth ratio, and axial load ratio, while strain gauges measured the CFRP shear contribution and informed the superposition model. Results show that the RC core behaves similarly to unstrengthened columns, the CFRP shear contribution depends on the tested parameters via a truss‑arch mechanism, and the proposed method predicts shear strength within reasonable agreement with the experimental data.

Abstract

Seven specimens were tested to investigate the shear strength of reinforced concrete (RC) columns strengthened by wrapping with a carbon-fiber-reinforced plastic sheet. All specimens were tested under lateral reversal cyclic loading and a constant axial load. The main parameters considered were the carbon-fiber-reinforced plastic (CFRP) sheet amount, the shear span/depth ratio, and the axial load ratio. Many strain gauges were attached to the CFRP sheet to obtain its shear contribution. It was found that the shear behavior of the RC part of the strengthened column was almost the same as that of the unstrengthened one. The parameters were found to have an influence on the shear contribution of the CFRP sheet, which could be explained by truss-arch shear resistance mechanism. A simple superposition method is suggested to calculate the shear strength of the strengthened column, in which a shear coefficient (ν) is proposed to evaluate the shear contribution of the CFRP sheet based on the test results. The calculated results of suggested method are shown to be in reasonable agreement with test ones.