Specimen Geometry and Toughness of Steel-Fiber-Reinforced Concrete

The first-crack strength and flexural toughness of steel-fiber-reinforced concrete specimens with different dimensions were determined using the procedures outlined in ASTM C1018 and JSCE-SF4 and the ASTM toughness indices and JSCE toughness parameters were calculated. It was found that variations in specimen size influenced not only the stress and deflection at first crack, and the ultimate strength, but also all the toughness parameters. The ASTM toughness indices and the JSCE toughness factor were both dependent on specimen dimensions unless the specimens were geometrically similar. It was found that toughness parameters decreased in an increase in the span-to-depth ratio of the specimens. All toughness parameters were significantly affected by the width of the specimen, even when both depth and span were unchanged; the toughness increased with an increase in width.