The shear strength of elements reinforced by fibres is predicted by Codes using formulations generally developed from a limited set of test results. In fact, only few of available test results are combined with a material mechanical characterization, allowing to evaluate and compare the different performances of Fibre Reinforced Concretes (FRC). To address this problem, a material-performance-based shear database for FRC elements and their related reference samples in Reinforced Concrete (RC, with and without web reinforcement) is presented herein, merging the experiences carried out in the last decade at the University of Brescia and at the Universitat Politècnica de València. The database is composed by 171 specimens: 93 in FRC and 78 in RC with or without web reinforcement. For FRC elements, the postcracking resistance (f R,1 and f R,3 ) is also given according to EN 14651 standard. The evaluation of the shear database was also carried out, discussing the influence of the different factors affecting the shear strength both in FRC and RC samples. Finally, the two formulations suggested by Model Code 2010 for FRC elements are compared against the database results in order to shed new light on code requirements.
The determination of the tensile properties of such a deflection hardening response material as UHPFRC is a serious challenge for both researchers and designers. This process involves many factors, such as specimen size, fibre orientation or test typology. The socalled inverse analysis is used to obtain the tensile constitutive properties that are consistent with the specimen response in a bending test. This work focuses on the inverse analysis process. The main aim is to develop a new back-calculation methodology, which is easy to implement, reliable, quick and is consistent with the measurements taken from a four-point bending test. The new methodology proposed has been validated using an analytical formulation and the experimental results of others authors. This paper also includes an application example of how this methodology works.
Shear behaviour in reinforced concrete (RC) elements can improve with an adequate amount of fibres. Research has recently determined how fibres affect shear strength, but has barely focused on macro-synthetic fibre-reinforced concrete (PFRC). This paper presents the experimental results of 16 full-scale beams (eight RC, eight PFRC), 12 without transverse reinforcement. Polypropylene fibres (10 kg/m 3 ) were included. Mode of failure (MOF) in shear and behaviour throughout the loading process were studied. The results obtained with fibres showed significantly improved shear strength in the RC beams with/without transverse reinforcement. A synergy between transverse reinforcement and fibres was observed in some cases. [1], tested 12 reinforced concrete (RC) beams in 1963 at the University of Berkeley in order to investigate critical shear behaviour. This beams series covered a wide range of transversal reinforcement and span conditions. The shear research community has considered this classical beam series to be a reference for calibrating numerical models. At the University of Toronto, Vecchio-Shim [2] reproduced classical Bresler-Scordelis beams in 2004 to test the repeatability of the results obtained by Bresler, particularly for load capacity and mode of failure (MOF).
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