Analisi sperimentale del comportamento flessionale di colonne in calcestruzzo fibrorinforzato

An experimental investigation on the behaviour of sixteen short, confined, reinforced concrete columns with and without steel fibers has been carried out. The 1:2 scale columns with square sections have concrete core 165x165 mm at the mid-section and haunched at the ends to apply the eccentric loading and prevent boundary effects. The specimens were tested to failure at different strain rates under two loading schemes: concentric compression and eccentric compression with a constant eccentricity. Axial load and axial strains were obtained to evaluate the effects of key parameters such as volume fraction of steel fibers, spalling of the concrete cover and eccentricity of the applied axial load. The comparative analysis of the experimental results shows that the presence of steel fibers delays the spalling load and increases the ultimate strength and the ductility; the thickness of the cover influences the peak load; the eccentricity of the applied axial load implies substantial variation in the peak load, ultimate strength and failure modes.