The results of an extensive experimental program into the location of the neutral axis in cracked fiber‐reinforced concrete (FRC) are reported. In total, 74 prisms are tested in a monotonic (51 specimens) and cyclic (23 specimens) bending test in accordance with EN 14651. In the program, 13 different FRCs are considered with 9 different fiber types and dosages. A normal strength concrete with residual strength values between 1b and 2d, cf. Model Code 2010 (MC10), is considered. The deformation profile in the cracked section is measured by side‐mounted linear variable displacement transducers on the prisms, and the position of the neutral axis is calculated. The experimental results are compared against predictions of the MC10. Based on a simplified stress diagram, the MC10 predicts that the location of the neutral axis depends on the residual strength of the FRC at the serviceability limit state: increasing the strength results in a larger compressive zone and vice versa. However, the results obtained within this study do not confirm this relation. The cyclic results indicate that the neutral axis shifts upward during unloading and subsequent reloading decreases the neutral axis again to preunloading levels. Finally, for all reported FRC types, the neutral axis lies very high in the cracked section, even at very small crack mouth opening displacement values.
Steel fiber reinforced concrete (SFRC) is known for improving the tensile post‐cracking fatigue behavior of concrete. This paper presents a method to obtain the cyclic tensile behavior of SFRC through sectional analysis, using a limited amount of input parameters. The analytical model is divided into two parts: a monotonic and cyclic model. The monotonic model calculates the uniaxial stress‐crack width curves or constitutive laws of SFRC that fulfill the beam's equilibrium with the smallest error. Afterwards, when the constitutive law is known, the cyclic model predicts the behavior during progressive load cycles. Two methods are used to implement the damage caused by cyclic loading: based on the experimental stiffness during cyclic direct tensile tests (DTTs) and based on a relation between the plastic crack width and the crack width at unloading. The latter option is preferred as no additional DTTs are needed. The proposed methodology therefore eliminates the need for challenging DTTs and only requires more feasible monotonic three‐point bending tests (3PBTs) for model calibration. The model is validated by means of DTTs and cyclic 3PBTs and its potential for extension to fatigue loading is shown.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.