BEHAVIOUR OF FIBRE REINFORCE CONCRETE BEAM IN PURE TORSION

Abstract

It has been observed that a plain concrete member when subjected to cracking torque fails along a spiral inclined at 45 0 to the axis of the member. It is obvious that reinforcement in the form of 45 0 rectangular spirals will be most effective in resisting torque in case of a member of rectangular section. Provision of only longitudinal bars without stirrups increases torsional strength to the extent of 15%, the most appropriate system of torsional reinforcement consists of longitudinal bars together with closed transverse stirrups. In view of above observations, an attempt is made to study the following aspects: Behaviour of reinforced concrete beam under. 1)Pure torsional, (a)Without glass fibres (b)With glass fibres 2)The effect of increase of fibre percentage on torsional resistance of beam. 3) To develop torque. Vs. twist relation of the beams. The experimental program consists of casting 4 reinforced concrete beams of size 150mm X150 mm and length 2m. Two of them were cast without fibres to make a comparative study with the remaining 3 beams; one beam is cast with 0.5% fibre by weight, one beam 1.0% fibre by weight in the rest one beam 1.5% fibre by weight added. The longitudinal reinforcement, spacing of shear stirrups is kept constant.