Shear behaviour of prestressed steel fibre concrete box-beams

Abstract

Six full-scale prestressed concrete box-beams are tested to study the effects of steel fibres on the increase in shear strength of beams. Beams are cast with no traditional transverse steel reinforcement. The amount of steel fibres and shear span-to-effective depth ratio are the main variables studied. The beams are subjected to concentrated vertical loads up to their maximum shear capacity using two actuators in load and displacement control mode. During the load tests linear voltage displacement transducers (LVDTs) are used to measure displacements at several critical points on the web in the end zone of the beams. Several LVDTs are also placed under the beams at the points of loading to measure the actual total and net displacements of the beams. From the load tests it is observed that the shear capacities of the beams increase with an increase in the amount of steel fibres and decrease as the shear span-to-effective depth ratio increases.