Title:
An Improved Prediction for Bond Strength of Deformed Bars in Concrete Externally Confined with Fiber- Reinforced Polymer
Author(s):
Zhenwen Xu and Dongming Yan
Publication:
Materials Journal
Volume:
120
Issue:
6
Appears on pages(s):
19-32
Keywords:
analytical model; bond strength; fiber-reinforced polymer (FRP) confinement; stress intensity factor (SIF); weight function
DOI:
10.14359/51739144
Date:
12/1/2023
Abstract:
External bonding with fiber-reinforced polymer (FRP) offers a
potential solution to mitigate the detrimental effects caused by
load impact and corrosion, which can weaken the bond strength
of reinforced concrete structures. However, existing models need
to be improved in addressing the FRP confinement mechanism and
failure modes. As a solution, the proposed model employs stress
intensity factor (SIF)-based criteria to determine the internal pressure exerted on the steel-concrete interface during various stages of comprehensive concrete cracking. Critical parameters are evaluated using weight function theory and a finite element model.
A bond-slip model is introduced for the FRP-concrete interface
and reasonable assumptions on failure plane characteristics. The
internal pressure model employed demonstrates that FRP confinement has the ability to generate dual peaks in stress distribution and modify their magnitude as the confinement level increases. The proposed predictive model demonstrates superior performance in failure modes, test methods, and wrap methods for assessing bond strength with FRP confinement. The accuracy of this model is indicated by an integral absolute error (IAE) of 9.6% based on 125 experimental data, surpassing the performance of the other
three existing models. Moreover, a new confinement parameter
is introduced and validated, showing an upper bound of 0.44 for
enhancing FRP bond strength. Additionally, a general expression
validating the bond strength model with FRP confinement is established, allowing for the prediction of bond length.