Numerical Modeling of Concrete Deep Beams Made with Recycled Aggregates and Steel Fibers

A bilinear tensile softening law that can describe the post-cracking behavior of concrete made with RCAs and steel fibers was developed based on an inverse analysis of characterization test data. Numerical simulation models were developed for large-scale concrete deep beams. The tensile softening laws along with characterization test results were used as input data in the analysis. The numerical deep beam models were validated through a comparative analysis with published experimental results. A parametric study was conducted to investigate the effect of varying the shear span-to-depth (a/h) ratio, steel fiber volume fraction (vf), and the presence of a web opening on the shear response. Results of the parametric study indicated that the shear strength gain caused by the addition of steel fibers at vf of 1 and 2% was higher in the deep beam models with a lower a/h of 0.8, relative to that of their counterparts with a/h of 1.6. The effect of a/h on the shear strength gain of the solid deep beam models diminished at the higher vf of 3%. The solid deep beam models with a/h of 0.8 exhibited a shear strength gain of 78 to 108% due to the addition of steel fibers, whereas their counterparts with the web opening experienced a reduced shear strength gain of 45 to 70%.