Shear behaviour of shallow beams in polypropylene fibre reinforced concrete

Many experiments available in the literature show that fibres, when provided in sufficient amount to guarantee an adequate toughness of Fiber Reinforced Concrete (FRC), are significantly effective as shear reinforcement. In fact, they limit the growth of shear inclined crack, give visible warning prior the structure collapse and also provide a stable and diffused crack pattern within the area of the element critical under shear. This paper reports recent results of an experimental campaign on Polypropylene Fibre Reinforced Concrete (PFRC) beams under shear loading tested at the University of Brescia, focusing on the beneficial influence of polypropylene fibres and the role of the width on the shear strength. Fourteen shallow beams with different widths and heights, fibre content and, also, minimum amount of classical shear reinforcements, were tested for evaluating the shear response of typical structural members utilized in Italy and in southern Europe in residential buildings. Results show that shallow beams do not have the typical brittle failure also with no shear reinforcement and the effect of polypropylene fibres is rather promising. Moreover, the comparison between polypropylene fibres and stirrups as minimum shear reinforcement is discussed