Stressing State Analysis of Reinforced Concrete Beam Strengthened by CFRP Sheet with Anchoring Device

Liang Luo,Jie Lai,Guorui Sun,Maoguo Yuan,Jun Shi,Jie Huang

doi:10.3390/ma14030576

Abstract

This paper investigates the working performance of reinforcement concrete (RC) beams strengthened by Carbon-Fiber-Reinforced Plastic (CFRP) with different anchoring under bending moment, based on the structural stressing state theory. The measured strain values of concrete and Carbon-Fiber-Reinforced Plastic (CFRP) sheet are modeled as generalized strain energy density (GSED), to characterize the RC beams’ stressing state. Then the Mann–Kendall (M–K) criterion is applied to distinguish the characteristic loads of structural stressing state from the curve, updating the definition of structural failure load. In addition, for tested specimens with middle anchorage and end anchorage, the torsion applied on the anchoring device and the deformation width of anchoring device are respectively set parameters to analyze their effects on the reinforcement performance of CFRP sheet through comparing the strain distribution pattern of CFRP. Finally, in order to further explore the strain distribution of the cross-section and analyze the stressing-state characteristics of the RC beam, the numerical shape function (NSF) method is proposed to reasonably expand the limited strain data. The research results provide a new angle of view to conduct structural analysis and a reference to the improvement of reinforcement effect of CFRP.

Highlights

Over the past several decades, Carbon-Fiber-Reinforced Plastic (CFRP) sheets or laminates that are lightweight, have high tensile strength, have non-corrosive characteristics, and assemble conveniently have been widely adopted for structural strengthening and repair to extend their service life [1,2,3]
The relevant findings indicated that the expected reinforcement effect was hard to achieve and the full tensile strength of CFRP could not be utilized, due to premature peeling failure of CFRP [12,13,14], which restricted the application of CFRP to some extent
In order to address the issues mentioned above, this paper investigates the flexural behavior of reinforcement concrete (RC) beams strengthened by CFRP with middle anchorage or end anchorage, based on the theory of structural stressing state and number shape function (NSF) method

Summary

Introduction

Over the past several decades, Carbon-Fiber-Reinforced Plastic (CFRP) sheets or laminates that are lightweight, have high tensile strength, have non-corrosive characteristics, and assemble conveniently have been widely adopted for structural strengthening and repair to extend their service life [1,2,3]. The use of CFRP is generally recognized as a practically efficient method to improve the load-carrying capacity and durability of damaged or deteriorating structures, it may still result in a lower ductility and possibly a brittle failure mode, due to the debonding of CFRP or sudden ripping of concrete [4,5,6]. In order to enhance the utilization efficiency of CFRP, postpone the structural debonding failure, and improve the capability and safety of reinforcement method, some approaches are proposed to resolve the peeling of CFRP from the concrete surface or delamination between CFRP layers. Grooving on the concrete surface could be an alternative method of surface preparation to effectively develop the bond performance between CFRP and concrete, resulting in the improvement of ultimate load capacity of strengthened beams, compared to those lacking any surface preparation [16,17]. Ferreira et al [19]

Methods

Results

Conclusion