Enhancing the flexural performance of lightweight reinforced concrete beams exposed to elevated temperatures

Abstract The deterioration of lightweight concrete (LWC) members due to intensive fires, necessitate the development of strengthening techniques for extending their service life. Fourty reinforced concrete (RC) beams were cast, heated at 600 °C for 3 hrs., strengthened using polymeric sheets (FRP), for regaining their flexural capacity. The flexural behavior of the beams investigated including the ultimate load, stiffness, deflection, and cracking pattern were described. The heated LWC reinforced beams regained a large portion of their load capacity, and exhibited typical flexural cracks in the pure bending zone, and flexure-shear cracks in the shear span, after strengthening. Among the strengthening schemes proposed, using a single layer and U shaped jacket of FRP sheets at the bottom, and sides of the beams, was effective for regaining their full flexural capacity. The experimental results indicated that FRP laminates can be considered as a promising material for maintenance and rehabilitation of heat damaged LWC members.