Numerically optimized post‐cracking branch of the constitutive tensile model for fiber‐reinforced concrete with natural and recycled aggregates.

This paper investigates the post‐cracking behavior of glass fiber‐reinforced recycled concrete (FR‐RAC). This was done on eight fiber‐reinforced concrete (FRC) mixtures, with three types of recycled aggregates (RAs), while the used fibers were the CEM‐FIL Minibars™ with a fiber content of 0.50 and 0.75 V%. Based on those investigated mixtures, it was found that the proposed constitutive tensile model of the fib Model Code 2010 and the model of di Prisco overestimate the measured load–CMOD curves. Therefore, the post‐cracking branch of the constitutive tensile model was numerically optimized. This was done by optimizing the ka and kc value in the simplified model (Equations 16 and 17), proposed by Vandevyvere and based on the model of di Prisco. The ka value relates to the tensile strength at serviceability limit state, while the factor kc relates to the tensile strength at ultimate limit state (ULS). The numerically optimized ka and kc value, abbreviated by ka' and kc', indicates a lower ka' value and a higher kc' value than the model of di Prisco et al. In addition, the extensive test data in this study show an increased post‐cracking behavior for the 0.75 V% mixtures with RAs. However, the ka' and kc' values are 0.325 and 0.710 for NAC‐0.75 V%, and only slightly different ka' and kc' values are obtained for the FR‐RAC mixtures. Therefore, one unified constitutive tensile model is proposed for all FRC mixtures. In addition, the numerically optimized model indicates a lower neutral axis location as well as a higher maximum tensile strain (εct,max) and compressive strain (εc,max) for the recycled concrete mixtures. The εc,max value at CMOD3 is 0.074‰ for NAC‐0.75 V%, while the nRAC‐0.75 V% mixture indicates a value of 0.100‰. This explains the improved fiber activation of the fiber‐reinforced recycled concrete mixtures (with 0.75 V% glass fibers). [ABSTRACT FROM AUTHOR]