Experimental investigation on high-strength fibre-reinforced concrete beams subjected to bending and shear

The results of an experimental campaign carried out on a number of high-strength concrete beams loaded in 4-point bending are presented in this paper, where the roles of the both steel hooked fibres and the transverse reinforcement are investigated, for different values of the shear span. All tests were displacement-controlled. The results – mostly in terms of load-deflection curves – confirm what is well known in the literature, that an adequate amount of steel fibres can turn a brittle shear-type failure into a ductile flexural-type failure, to the advantage of the ultimate bearing capacity in flexure and shear, that can be fully exploited without increasing the transverse reinforcement. By applying a number of strain gages to the most stressed stirrups, the effectiveness of the fibres as a partial replacement of the shear reinforcement was investigated, in order to calibrate the coefficients that appear in the empirical relations concerning the evaluation of the ultimate shear capacity.