The performance of Strengthened Lightweight RC Beams with different Techniques upon Exposure to Fire

Reinforced concrete beams are used in a wide range of applications. In addition, reducing the weight of the concrete used increases the advantages of the beams. The main objective of this work is to study the performance of structurally strengthened lightweight reinforced concrete beams with different techniques with or without exposure to fire under concentric load and the efficacy of the fire protection system.

The experimental specimens included eight half-scale tested rectangle beams with typical dimensions of 300 mm depth, 1700 mm total length, 150 mm total width, 50 mm cover, and 1500 mm span. The density of the lightweight polystyrene foam concrete was 1820kg/m3. The main parameters were fire resistance, different types of strengthening material for lightweight concrete beams, shape of the ferrocement layer on the lightweight concrete surface, and ferrocement thickness.

The results were analyzed in terms of crack patterns, failure modes, load deflection, load-strain behavior, stiffness, ductility, deformability, and absorbed energy.

From the analysis of the results, the strength of LWC beams increased the strength and stiffness of the tested beam, and the fire protection system was found effective in protecting CFRP limitation from deterioration. In a theoretical study, the conservatism degree for calculating the maximum allowable flexure force was evaluated according to the ECP203, ACI-318, and BS-8110 codes.