Moment redistribution and post-peak behaviour of lightly reinforced-SFRC continuous slabs

Abstract

The ductility and post-peak behaviour of conventionally reinforced steel fibre reinforced concrete (R-SFRC) flexural members have been found to be dependent on the volume of tensile reinforcement. Although few studies have investigated the effect of low reinforcement volume on the ductility and post-peak behaviour of simply supported and continuous members, no study was found for continuous members that were designed for moment redistribution. Further, no prior studies have investigated the ability of lightly reinforced-SFRC continuous members to redistribute moment, or if the achievement of the maximum amount of moment redistribution in design standards is possible. Because of the lack of research in this area, strict limitations are placed in standards for moment redistribution in lightly reinforced-SFRC continuous members. Thus, an experimental study was undertaken for six full-scale two-span continuous one-way slabs with the objectives of determining the moment redistribution capability of lightly reinforced-SFRC continuous members and effect of low reinforcement volume on the ductility and post-peak behaviour of R-SFRC continuous members. The nominal dosage of steel fibres in the R-SFRC slabs was 60 kg/m3 and the tensile reinforcement ratios were between 0.0021 and 0.0042 to provide for bending moment redistribution up to 30% of the linear elastic bending moments. The test results showed that the lightly reinforced-SFRC slabs achieved the designed and maximum amount of moment redistributions and had sufficient ductility, but the R-SFRC slabs showed a softening behaviour after the ultimate load whereas the reinforced concrete (RC) slabs showed a hardening behaviour. Consequently, the post-peak behaviour of R-SFRC flexural members was formulated mathematically. Finally, the rectangular stress block model of AS 3600:2018 was found to determine the capacity of the R-SFRC slabs with reasonable accuracy.