Title: Effectiveness of CFRP Sheets for Torsional-Strengthening of Reinforced Concrete Beams

Author(s): Yail J. Kim and Abdulaziz Alqurashi

Publication: Structural Journal

Volume:

Issue:

Appears on pages(s):

Keywords: carbon fiber reinforced polymer (CFRP); rehabilitation; strengthening; torsion

DOI: 10.14359/51740867

Date: 6/4/2024

Abstract:
This paper presents the torsional behavior of reinforced concrete beams strengthened with carbon fiber-reinforced polymer (CFRP) sheets. Assorted retrofit schemes are implemented with the variable width and number of single- and double-layered CFRP U-wraps. After loading 27 beams (3 unstrengthened and 24 strengthened), test data are collected to investigate the efficacy of those U-wrap configurations. The width and layer of the bonded sheets dominate the capacity of the beams, whereas the number of the U-wraps in the longitudinal direction is an insignificant attribute. Although the CFRP retrofit decreases structural ductility, the placement of the U-wraps impedes stiffness-reduction rates, reduces twist angles, and redistributes torque-induced stresses. The identified characteristic effective shear modulus of the strengthened beams demarcates the pattern of energy drops, which are replated to the degree of brittleness in failure. As far as effective strains are concerned, the applicability of existing equations is appraised and a new expression is proposed through reliability theory and stochastic simulations.