Test-aided calibrations for design of steel fibre reinforced recycled aggregate concrete beams

This research proposes to combine recycled aggregate concrete (RAC) with steel fibres (SF), to provide an environment-friendly, sustainable, and structurally sound alternative to natural aggregate concrete (NAC). When steel fibre reinforced recycled aggregate concrete (SFRRAC) is used in construction, the existing design equations and associated safety factors need to be revised; the existing design provisions are applicable only to NAC and cannot be applied to SFRRAC directly. In this research, safety factors of design equations for beams provided in the current Australian, American, and European design codes are calibrated based on the first-order reliability method (FORM) when used for the structural design of SFRRAC beams. This is carried out based on a proposed prediction model for the flexural capacity of SFRRAC, which considers the contribution of SF unlike the conventional prediction model for RC beams. The uncertainty of the prediction model is estimated based on nine experimental results of secondary SFRRAC beams tested for flexural failure under three-point bending. These beams are fabricated with varying contents of recycled aggregate and steel fibre ratios. Furthermore, the reliability index ratios of the different SFRRAC mixes considered are estimated.