Dynamic behaviours of spiral-shaped steel fibre reinforced concrete under splitting tension: Experimental and numerical study

Abstract

Concrete is strong in compression but weak in tension with brittle fracture characteristics. To increase its ductility and post-cracking load-carrying capability, intensive researches have been reported to add various types of fibres into concrete mixture. A new type of steel fibre with spiral shape has been recently proposed. Laboratory tests demonstrated that compared to other fibre types such as hooked-end, deformed and corrugated fibres, this new fibre has larger displacement capacity and provides better bonding into the concrete matrix. However, the dynamic properties, especially tensile properties, of concrete reinforced with spiral-shaped steel fibres need be further investigated for a better understanding of this material and potential application in critical engineering buildings/infrastructures against blast and impact loads. This study carries out split Hopkinson pressure bar (SHPB) tests and numerical simulations to study the behaviour of spiral fibre reinforced concrete (SFRC) under dynamic splitting tension. In SHPB tests, tapered striker bar was used to generate stress wave with half-sine shape so that stress wave oscillation and dispersion were eliminated. The simulations are implemented using commercial software LS-DYNA as a plane-stress problem. The SFRC specimens are modelled in mesoscale with distinctive consideration of mortar matrix, coarse aggregates and spiral fibres. The numerical simulation results are compared with SHPB test data. The validity and feasibility of the mesoscale numerical model in analysing behaviours and properties of SFRC under dynamic splitting tension are demonstrated. The influence of fibre contents on the dynamic splitting tensile strengths of SFRC material is parametrically studied.