The onset of cracking and ductility of steel fiber concrete

The influence of steel fiber reinforcement on the onset of cracking, ductility and energy absorption capacity in flexure is reported. The automatic load-deflection curve predicts a consistently higher load for the onset of cracking than those obtained from strain, pulse velocity and deflection measurements. Fiber reinforcement increases the onset of flexural cracking. However, there is a minimum fiber volume below which only the onset of cracking is increased without any increase in the ultimate flexural strength. The most significant role of fiber reinforcement lies in increasing the post-cracking properties of ductility, tensile strain capability and energy absorption capacity. The increase in flexural modulus is nominal but the resulting crack control and strain capability can be used in design to enhance the serviceability behavior of conventional structural members by the provision of a fiber tensile skin.