The effectiveness of glass fiber reinforced polymer retrofitting of reinforced concrete beam under high temperature exposure

Abstract

Structures exposed to fire will lose their strength and might be abandoned as a high cost is required to restore the structures. However, strengthening of old or damaged structures is sometimes may be more economical compared to demolishing or rebuilding them. For reinforced concrete (RC) beam structure, the flexural strength can be improved by installing additional reinforcement materials such as Glass Fiber Reinforced Polymer (GFRP) at the tension part of the beam’s cross-section. This paper presents an experimental investigation of the flexural strength of a total of seven (7) RC beam specimens. Six (6) specimens were burned at a temperature ranging from 200°C to 600°C. Four (4) of the burned specimens were then, retrofitted with Glass Fibre Reinforced Polymer (GFRP). The remaining beams were used as control specimens. The flexural strength of the beam specimens is determined from three points bending test, using a Universal Testing Machine (UTM). The effectiveness of using GFRP as a retrofitting material in order to improve the flexural strength of the beam was investigated and the crack behaviour were observed. Results from the experimental testing showed that, the flexural strength of the beams decreases as the temperature increases. However, the flexural strength of the specimens retrofitted with GFRP increased by 21% and 23% for specimens burned at 200°C to 600°C respectively. Therefore, it can be concluded that utilizing GFRP as a retrofitting material through Near Surface Mounted (NSM) technique is effective to improve the flexural strength of RC beam even after high temperature exposure.