Tests of steel fibre reinforced concrete beams under predominant torsion

• Studied the effects of steel fibres on torsional strength.
• Steel fibre addition improved torsional strength and combined torsional-bending strength.
• Improved crack resistance and decrease in the deflection.
• Suggested modified coefficient of the empirical formulae.

The use of steel fibres in plain concrete helps in improving the mechanical properties of concrete structure. Thus the aim of present study is to investigate the effect of steel fibres on torsional strength improvement of concrete. The research evaluates the torsional strength and combined torsional-shear-bending strength. In this study, 20% of fly ash (class-C) is added as a replacement of binder to its weight and 1.5% steel fibres by weight of concrete. Experimental results show an improvement in torsional strength, combined torsional-shear-bending strength and crack resistance of concrete by addition of steel fibres in the concrete and a decrease in the deflection. Based on the experimental results the modified coefficient of the empirical formulae has been suggested to predict the torsional strength and torsional stress of steel fibre reinforced concrete.