Fibre reinforced concrete subjected to pure shearing testing: Experimental comparison with structural concrete codes modelling

Abstract

Nowadays, steel and polymeric fibres are the most used for performing fibre reinforced concrete (FRC). The behaviour of FRC depends on factors such as material and shape of the fibres, dosage and distribution and orientation of the fibres in the FRC structural element. From a design point of view, the structural codes consider the contribution of fibres based on bending tensile tests. With the data provided by these tests and with the constituent relationships of the material it is possible to use the reinforcing fibres in the structural design. However, there is still a lack of research that addresses in detail the behaviour of FRC on shear strength, especially in case of polyolefin fibres. The study of the shear strength of FRC with polyolefin fibres is a challenge. In addition, several studies have shown that, with fibre reinforcement, it is possible to significantly reduce, and even eliminate, the reinforcement of stirrups with steel bars due to the structural contribution of the shear fibres. Different types of tests such as JSCE-SF6, double-specimen to shear, Iosipescu and push-off have been used to analyse pure shear stress. The latter developed a research campaign on four concretes reinforced with polyolefin fibres and two others with steel fibres, previously bending tested. The experimental results are compared with the design calculation values obtained through normative formulation, resulting in the values conforming to the regulations being conservative for small shear displacements, in the order of 0.5mm. However, for shear slip at 2.5mm, the design values proposed by the structural codes may be higher than those shown experimentally. © Fédération Internationale du Béton (fib) – International Federation for Structural Concrete.