Testing of Fibre Reinforced Concrete: Shear Capacity of I-Beams

Abstract

A series of full-scale steel fibre reinforced I-beams with varying web width has been tested in shear failure. A rectangular steel fibre reinforced beam and a conventionally reinforced I-beam have also been tested for comparison. The concrete used is a self-compacting concrete with a B45 classification. The concrete contains 1%vol (78,5kg/m3) steel fibres with end-hooks of type Dramix 3D 65/60. The load-deflection and load-shear crack opening response has been analysed for all beams and been compared with each other. A fibre count has also been conducted to investigate the influence the element size has on the fibre orientation. The results have been compared with guidelines from COIN and Model Code based on residual flexural tensile strengths from small beam tests according to NS-EN 14651. The report also gives an introduction of steel fibre reinforced concrete and design guidelines used to estimate the shear capacity. The results show that steel fibres have a significant effect on the shear capacity. All beams had more capacity than expected based on calculations made prior to testing. The ultimate shear capacity seems to be higher for I-beams than rectangular beams. A high fibre orientation factor in the longitudinal direction is found in the web in all beams, though a low representation of fibres around the tensile reinforcement. The orientation factor seems to increase with more slender elements. A good correlation between ultimate shear capacity and fibre orientation factor is not found within the range studied. However, the load at first crack seems to increase with higher longitudinal fibre orientation factor. An increase in the first crack load is also found for the SFRC beam compared to the beam with stirrups.