Influence of Maximum Aggregate Size on Behavior of Reinforced Concrete Beams under Pure Torsion

Abstract

This study investigates the influence of the maximum size of course aggregate on the torsional behavior of reinforced concretebeams subjected to pure torsion.The experimental program consists of a total of twelve rectangular reinforced concrete beams of dimension (150 mm x 150mm) and length 1500mm, the beams (B1 to B9)are divided into three groups based on the maximum aggregate size (9.5, 19,25mm)and amount of the applied torque represented by the torque lever arm (x =300,500amd 800mm).The beams are designed for the same concrete strength of about (36Mpa),additional concrete beams (group4), B10, B11, and B12 are designed for various concrete compressive strengths. Allbeams are reinforced with (4O12mm)longitudinal bars and without transverse reinforced in the study area. The experimental results show that the cracking and ultimate torque at failure are reduced as the amount of the applied torque or the torque lever arm is increased from (300 to 800mm).Additionally,test results show that the maximum size of the coarse aggregate has small effects on the torsional behavior of the beams, the behavior is not clear in beams with approximately the same concrete strength, while the behavior is moreclear and the cracking and ultimate torque are improved as the concrete compressive strength is increased.