Análise comparativa de modelos constitutivos multilineares de concreto reforçado com fibras de aço (Comparative analysis of multilinear constitutive models of steel fiber reinforced concrete)

The challenging task of structural design under structural safety, economic efficiency and environmental sustainability constraints has led to the development of several efficient materials. In this context, steel fiber reinforced concrete (SFRC) stands out due to the post-cracking behavior related to its enhanced toughness. Recent structural design normative codes consider this composite, suggesting good structural performance and broadening its applicability. Nevertheless, literature still lacks a comprehensive constitutive model to precisely describe its tensile behavior. This paper analyzes and compares three of the main European constitutive models, investigating factors that possibly influence their behavior. This study was conducted based on the cross-sectional analysis method, so that load-CMOD graphs could be obtained. Statistical analysis was conducted to classify the models, regarding several relevant parameters, such as mean compressive strength of the matrix and fiber volume. Results show that the constitutive law proposed by the fib Model Code shows the best performance. Also, from the set of considered parameters, ultimate tensile fibers strength presents the greatest sensitivity concerning structural post-crack behavior.