14 - Shear strength assessment of reinforced recycled aggregate concrete member

Abstract

While extensive studies have been conducted on recycled aggregate concrete (RAC) beams in shear, its complexity has caused great difficulty in gaining a thorough understanding of its behavior. This poses a critical issue in developing a general and accurate formulation for the shear strength of RAC beams. The underestimation of the shear resistance poses critical safety issues; conversely, the overestimation is uneconomical. This study reviewed the shear behavior of RAC beams without shear reinforcements and assessed the state of the practice’s existing design methods available in international standards and published literature in predicting the shear strength of RAC beams reliably. The existing shear design methods considered include the equations according to EN1992–1–1:2004, ACI318–2014, Compression Chord Capacity model, and Pradhan et al. model. The existing design equations were assessed using an experimental database of RAC and fly ash-based recycled aggregate concrete (FARAC) beams without stirrups. The accuracy and precision of the methods in predicting the shear strength of the RAC beams were assessed through the statistical characterization of their model factor, obtained as the ratio of test-to-predicted shear strengths. Generally, the existing methods predict the shear capacity of RAC and FARAC beams conservatively with large scatter, with ACI 318–14 as the most conservative. All the methods generally did not fully account for all the influential parameters found to affect the shear behavior of RAC beams. The performance of the design methods can be improved through the reliability-based calibration of partial material factors or the introduction of resistance adjustment factors to account for the bias and uncertainties in their shear resistance predictions.