Experimental and numerical studies on shear behaviour of macro-synthetic fibre reinforced prestressed concrete beams

Experimental and numerical studies on shear behaviour of macro synthetic fibre reinforced prestressed concrete (MSFRPC) beams are presented. MSFRPC beams are tested at a shear span to depth ratio (a/d) of 2.4 to understand the role of macro synthetic polyolefin fibres on the shear resistance and failure modes. The fibre volume fraction of 0.0%, 0.5%, 1.0% and 1.5% are considered as study parameters. A three-dimensional nonlinear finite element (FE) analysis is carried out to understand the influence of fibres on shear behaviour using the concrete damage plasticity model. Tensile constitutive relations of FRC is derived using inverse analysis from fracture test results and used as input in the FE model. A stage-wise analysis is conducted to include the effects of prestressing and applied external shear loads. The results from FE analysis showed a good agreement with experimental results for different fibre dosages. The effect of level of prestressing and varying compressive strength is studied through calibrated FE models. Due to the addition of macro synthetic fibres, no significant improvement in compressive strength is observed. Low fibre volume addition of 0.5% did not produce an appreciable improvement in shear behaviour. However, test and FE results of beams with higher volume fractions of 1.0% and 1.5% significantly improved the post-cracking behaviour, ductility, and ultimate shear resistance of MSFRPC beams.