Sequential Cracking and their openings in steel-fiber-reinforced joint-free concrete slabs

Numerical and empirical models addressing the drying shrinkage cracking behavior of joint-free steel-fiber-reinforced concrete (SFRC) slabs are presented. Effect of water-cement ratio, admixtures, and free shrinkage are considered. Mechanical restrictions including base friction, fiber dosage, and interfacial bond properties restrain the growth of microcracks into main cracks and also reduce crack opening. A model based on a finite-difference equilibrium solution of a one-dimensional (1D) slab on frictional ground simulates the formation and subsequent opening of cracks in the slab. Results are compared with an empirical predictive tool for crack opening. A sensitivity study shows that correlation of predicted crack opening reduced by increasing fiber volume, base friction, and interfacial bond strength. Case studies are conducted on three slabs in service at different occasions and both models are used to predict the crack opening. While these models are developed based on different methodologies, they are related to a great extent by addressing the same mechanical characteristics. A simple method to estimate the slab curl is proposed and a parametric study has been conducted.