Torsional Behaviour of Plain and Reinforced Normal Strength Concrete Beams.

Abstract

Abstract : Concrete as building material has a complex behavior phenomenon at micro structure in transferring of stresses between the ingredients, Changes in the mechanical properties, change the cracking and failure behavior and is not clearly understood the behavior of beams, in the case of mechanism of pure torsion, torsion with bending, torsion with shear and the formulas developed for the calculation is wholly or partly empirical. To understand the behavior, an experimental investigation was carried out to study the Torsional behavior of the reinforced Normal Strength Concrete (NSC) beams with the mix proportion of 1:1.57:2.48:0.44 concrete grade M40. Twelve NSC beams with constant width (100 mm), depth (100 mm), effective span 800mm without steel as plain beam, with varying longitudinal reinforcement and nine beams with varying longitudinal and transverse reinforcement ratio were tested under the standard testing procedures. The parameters studied in this investigation are ductility behavior, cracking torsional strength, ultimate torsional strength, failure pattern, Torque-rotation behavior, torsional stiffness, strains and comparison of torque resistance with plain and reinforced beams. The ratio of the experimental to that of the predicted torsional moment by different theories and codes were calculated. The mean, standard deviation and the coefficient of variation was obtained. Based on these observations, conclusions were drawn.