EFFECT OF FIRE ON SHEAR BEHAVIOR OF RC BEAMS

In this research, the effect of fire exposure time and the concrete co ver thickness on the behaviour of R.C. beams subjected to fire in shea r zone and cooled by water is investigated. Eight reinforced concrete beams (180 x 20 x 12 cm) were investigated. The beams were divided int o two groups. Group (1) consists of four beams with a cover thickness of 2 cm and group (2) consists of four beams with a cover thickness of 4 cm. Each group was subjected to a fire of 650 degrees C for differe nt periods of time, i.e. 0, 30, 60, 120 min. The concrete compressive strength of the beams was determined nondestructively by using a Schmi dt hammer the next day after exposure to fire. The beams were tested b y applying two transverse loads incrementally. Strains and deformation s were measured at each load increment. Cracking loads, crack propagat ion and ultimate loads were recorded for each beam. The behaviour of t he beams exposed to fire in the shear zone is highly affected by the f ire exposure time and the change of the cover thickness. (C) 1997 Else vier Science Ltd.