Experimental investigation of the shear response of large-scale fibre-reinforced concrete panels

Although fibre-reinforced concrete has been the subject of extensive research for decades, its mechanical behaviour in shear is still not well understood. Furthermore, hardly any large-scale shear tests on elements with moderate fibre contents have been conducted to date. The present paper addresses this knowledge gap by presenting and discussing the results of an experimental campaign on large-scale fibre-reinforced concrete shear panels. Six panels with dimensions of 2.00 m x 2.00 m x 0.27 m were tested in the Large Universal Shell Element Tester at ETH Zurich by applying homogeneous shear. In four of these experiments, the in-plane shear was combined with homogeneous uniaxial compression by simulating the longitudinal restraint provided by the chords in a girder. Five tests focused on concrete of normal strength with moderate fibre contents and one test studied the behaviour of ultra high-performance fibre-reinforced concrete. The combined application of digital image correlation instrumentation and distributed fibre optical sensing allowed gaining a deeper insight into the structural behaviour of the panels. Overall, the test results showed the high efficiency of the fibres as shear reinforcement in large-scale web elements. However, failure of the panels without any steel reinforcing bars was rather brittle, with only few cracks forming over the element. The provision of a moderate amount of distributed longitudinal bar reinforcement has been found to be highly beneficial to the crack behaviour and thus significantly increase the ductility.