Experimental study of a rehabilitation solution that uses GFRP bars to replace the steel bars of reinforced concrete beams

Patrícia Escórcio,Paulo M França

doi:10.1016/j.engstruct.2016.09.013

Abstract

The corrosion of the steel reinforcement affects drastically the long-term durability of many reinforced concrete (RC) structures in the world, especially the ones near the sea. When this problem is detected at early stages, it is possible and important to repair the structure in order to restore its safety and avoid future hazards and more expensive interventions. The research work described in this paper is inspired on these cases as it proposes a rehabilitation solution to replace the tension steel reinforcement of a RC beam with GFRP bars, which is a material immune to corrosion.The experimental study consisted on six full-scale RC beams subjected to a three-point bending test until failure. The specimens had stirrups without the bottom branch and were casted in two phases to simulate the replacement of the corroded and cracked bottom concrete. Two different GFRP reinforcement ratios were tested to assess the behaviour of the repaired beam regarding its service and ultimate states in comparison with the original beam with steel reinforcement. The results are presented and discussed in terms of flexural capacity, failure modes, deflection, crack pattern, mid-span crack width and reinforcement strains. It was concluded that the presented rehabilitation solution is easy to implement, can be designed according to general FRP design guidelines, and is able to restore the serviceability and ultimate limit states of the original RC beam.

Highlights

Structural rehabilitation is becoming increasingly important nowadays
1.44 1.64 a It was used the formulas of the EC2 or the FIB40, whether the prediction/design result was for the reinforced concrete beam with steel or GFRP bars, respectively
Concerning the beams with bottom longitudinal steel reinforcement, the REHABSTEEL beam presented a load-carrying capacity (89.81 kN) only 4.5% lower than the reference beam (REF) beam (94.06 kN), which proves that the rehabilitation solution works and is not affected by the new concrete layer

Summary

Introduction

Structural rehabilitation is becoming increasingly important nowadays. The amount of deteriorated structures, the frequency and the costs of rehabilitation interventions motivate the introduction of innovative materials and methods to rehabilitate structures. The service behaviour and the ultimate performance of reinforced concrete (RC) are shortened by the corrosion of steel reinforcement [1,2]. Corrosion of the reinforcement induced by chloride environments has a significant effect on the mechanical behaviour, and the loss of cross-sectional area and bond strength of reinforcement have a very important effect on the bending capacity [3]. Malumbela et al [1] concluded that for a maximum mass loss of 1%, the flexural capacity was reduced by 0.7%. Repairing, rehabilitating and strengthening solutions are being developed and tested using different materials and different layouts. Solutions with steel materials can have limited duration. Fibre Reinforced Polymers (FRPs) have been used because of their

Objectives

Methods

Results

Conclusion