GFRP-Reinforced Concrete Slabs: Fire Resistance and Design Efficiency

Abstract

Thickening concrete cover to obtain an adequate fire resistance lowers the efficiency of glass fiber–reinforced polymer (GFRP) reinforcement and increases the cost relative to conventional steel reinforcement. This paper investigates the fire resistance of two full-scale GFRP-RC slabs with only 40 mm of clear concrete cover and 200 mm of unexposed (cool) anchor zone at the ends. Both slabs endured 3 h under the standard fire. The slabs were loaded with a sustained load, which caused a moment equal to 45% of their ultimate flexural strength. Emphasis was placed on studying the bond behavior of GFRP bars by comprehensively investigating temperature distributions particularly at the unexposed anchor zones at the ends of the slabs. The temperature reduces significantly in the unexposed zones, providing an adequate anchorage for the bars when almost the entire GFRP-to-concrete bond deteriorated in the exposed zone. The analysis of the experimental results showed that the increase in the tensile force in the GFRP bars during the standard fire is below 50% of the existing sustained force. A new model considers the bond degradation to predict the fire resistance of GFRP-reinforced slabs. The results enable an efficient, economic, and fire-safe application of GFRP reinforcement in concrete construction by reducing the concrete cover.