Shear behaviour of hybrid fibre-reinforced SCC T-beams

Abstract

Three series of simply supported hybrid-fibre-reinforced self-compacting concrete T-beams subjected to four-point symmetrically placed vertical load were experimentally investigated. The influence of the following variables was studied: the fibre type, the fibre content, the stirrup ratio and the flange size. Failures were consistently shear or shear–flexure failures, except in five T-beam specimens where the failure was dominated by flexural cracks. The results showed that hybrid fibres can evidently enhance the ultimate shear load. The addition of hybrid fibres in adequate amounts can change the failure mode. The influence of different flange size on the ultimate shear load of the T-beams should be considered. Three methods were proposed – the ‘effective width’, ‘form factor’ and ‘shear funnel’ – for predicting the ultimate shear load of steel-fibre-reinforced self-compacting concrete T-beams, and another two methods were proposed – the ‘revised σ–w design method’ and ‘revised σ–ε design method’ – for predicting the ultimate shear load of hybrid fibre or steel-fibre-reinforced self-compacting concrete T-beams. The ultimate shear load recorded experimentally was compared with the value obtained from the proposed equation. The ‘revised σ–w design method’ was more suitable for predicting the ultimate shear load of T-beams containing hybrid fibres and/or with stirrups, and the correlation was satisfactory.