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Abstract：Based on the investigation of fiber influence on workability of self-compacting concrete (SCC), tests were carried out on two series of SCC rectangular simply supported beams, which were made of hooked steel fibers reinforced concrete with or without stirrups, subjected to four-point symmetrically placed vertical loads. The major test variables are steel fiber contents and stirrup ratios. The results indicate that the ultimate load significantly increases with the increase of fiber content; the addition of steel fibers in adequate percentage can change the failure mode from a brittle shear collapse into a ductile flexural mechanism. The stirrups can be partially replaced by steel fibers. The combination of stirrups and steel fibers demonstrated a positive hybrid effect on the mechanical behavior.Diagonal cracks of a reinforced concrete beam occur when the principal tensile stress of concrete within the shear span exceeds the tensile strength of concrete. The addition of steel fibers into a reinforced concrete beam can enhance its shear failure strength, and if sufficient steel fibers are added, a brittle shear failure can be suppressed in favor of more ductile behavior, and crack sizes and spacing can also be reduced [1][2][3][4][5] . Steel fibers were used to boost the shear capacity of concrete or to partially replace the vertical stirrups in reinforced concrete structural members. This relieved reinforcement congestion at critical sections such as beam-column junctions and tubbing segments [2,6] .The interfacial bond behavior between aggregates and paste for self-compacting concrete (SCC) is better than that for normal concrete, and also the internal defects of SCC are less than that of normal concrete [7,8] . The difference between fiber reinforced SCC (FRSCC) and traditional fiber reinforced concrete (FRC) is that fiber content of FRC is mainly determined by the post cracking behavior, and the fiber content of FRSCC is strongly restricted by the workability of fresh SCC. Greenough et al [8] have concluded that FRSCC beams without stirrups displayed superior shear performance compared with that of conventional FRC beams without stirrups, because better workability and the elimination of mechanical vibration led to a more homogeneous dispersion of fibers. The construction period and costs as well as the binding of reinforcement may be significantly reduced by using FRSCC. FRSCC can also be easily placed in thin or irregularly shaped sections, where it may be very difficult to place stirrups. The investigation on FRSCC is a new development trend, which has advantages of both SCC and FRC. However, the study on FRSCC beams is still limited.In this paper, the results on shear behavior of steel fiber reinforced SCC beams are presented. The main purpose of the test program is to evaluate the possibility of replacing stirrups with steel fibers, and to analyze the influence of steel fiber on failure mode. 1 Test program Beam geometry and setup descriptionTwo series of steel fiber reinforced SCC beams (SFSCCBs...

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.