Tests and Design Provisions for Reinforced-Concrete Beams Strengthened in Shear Using FRP Sheets and Strips

Amir Mofidi,Omar Chaallal

doi:10.1007/s40069-013-0060-1

Abstract

Numerous investigations of RC beams strengthened in shear with externally-bonded (EB) fibre-reinforced polymer (FRP) sheets, plates and strips have been successfully conducted in recent years. These valuable studies have highlighted a number of influencing parameters that are not captured by the design guidelines. The objective of this study was: (1) to highlight experimentally and analytically the influential parameters on the shear contribution of FRP to RC beams strengthened in shear using EB FRP sheets and strips; and (2) to develop a set of transparent, coherent, and evolutionary design equations to calculate the shear resistance of RC beams strengthened in shear. In the experimental part of this study, 12 tests were performed on 4,520-mm-long T-beams. The specimens were strengthened in shear using carbon FRP (CFRP) strips and sheets. The test variables were: (1) the presence or absence of internal transverse-steel reinforcement; (2) use of FRP sheets versus FRP strips; and (3) the axial rigidity of the EB FRP reinforcement. In the analytical part of this study, new design equations were proposed to consider the effect of transverse-steel in addition to other influential parameters on the shear contribution of FRP. The accuracy of the proposed equations has been verified in this study by predicting the FRP shear contribution of experimentally tested RC beams.

Highlights

The last two decades have witnessed a growing demand for strengthening and rehabilitation of existing reinforced concrete (RC) structures
Recent findings have highlighted major influential parameters related to shear strengthening with externally-bonded (EB) fibre-reinforced polymer (FRP) that have still not been captured by current predictive models, including standard codes and guidelines (Mofidi and Chaallal 2011a, b)
The objectives of this study were: (1) to investigate experimentally and analytically the effect of the influential parameters which have been found to affect the shear resistance of EB FRP; and (2) to propose a set of transparent, rational, and evolutionary design equations to calculate the shear contribution of EB FRP to the shear resistance of strengthened RC beams

Summary

Introduction

The last two decades have witnessed a growing demand for strengthening and rehabilitation of existing reinforced concrete (RC) structures. In the 1990s, researchers paid more attention to the potential applications and benefits of using fibre-reinforced polymer (FRP) material to strengthen RC elements. This enthusiasm was due to the attractive characteristics of FRP, such as high strength-to-density ratios, chemical and corrosion resistance, and easy construction and handling. The objectives of this study were: (1) to investigate experimentally and analytically the effect of the influential parameters which have been found to affect the shear resistance of EB FRP; and (2) to propose a set of transparent, rational, and evolutionary design equations to calculate the shear contribution of EB FRP to the shear resistance of strengthened RC beams

Objectives

Methods

Findings

Conclusion