The Effect of Concrete Cover Thickness on the Torsional Resistance of Fibrous, High-strength, Under-reinforced Concrete Beams

Abstract

This study focuses on the role of concrete cover in enhancing the torsional resistance of peak load in under-reinforced fibrous high-strength concrete beams. In this study, the primary variable that varied from 17 mm to 53 mm was the concrete cover thickness. Four rectangular solid beams were cast and tested to determine the effect of concrete cover thickness on the behaviour of under-reinforced fibrous, high strength concrete beams subjected to pure torsional loading. The test results revealed an 80.6% improvement in the torsional resistance at peak load. In addition, at maximal loads, the twisting angle, shear strain in concrete, transverse reinforcement strain, and longitudinal reinforcement strain were reduced by 70.2%, 90%, 50.6%, and 34.5%, respectively.  It is therefore possible to draw the conclusion that the concrete cover has a new function, which is an improvement in torsional resistance at ultimate load that is in addition to protecting the reinforcement from corrosion.