Evaluation of flexural strength prediction of reinforced concrete beams with steel fibres

Abstract

This paper presents experimental programme to investigate the effects of steel fibres on flexural strength of steel fibre-reinforced concrete (SFRC) beams and proposes a prediction model to evaluate flexural strength of beams which is their main contribution to literature. Four point bending test was carried out on the 11 SFRC beams which are 6 normal-strength SFRC beams and 5 high-strength SFRC beams. The variables studied in the investigation were steel fibre volume fractions (0, 0.75 and 1.50%), flexural reinforcement ratios (1.0 and 2.0%), and concrete compressive strengths (28 and 56 MPa). The test results confirmed that ultimate flexural strength increased with increasing fibre volume contents. The constitutive model for SFRC was proposed, which incorporated strength of fibre-reinforced concrete and strain-hardening of tensile reinforcement. Predictions of moment–curvature relationship based on the model matched well with the experimental data. The results of previously reported tests were combined with the results of new tests to document observed flexural failures of 129 SFRC beams. A simplified, empirical design equation to determine the flexural strength of SFRC beam was proposed and compared with existing equations. The analysis indicated that the proposed equation provided the most accurate estimates of flexural strength.