Shear behaviour ofultra-high- performance fibre-reinforced concrete beams without stirrups

摘要

The experimental results of shear strength and deformation tests for 12 ultra-high-performance fibre-reinforced concrete (UHPFRC) beams without stirrups are presented in this paper. I-beam specimens with a depth of 700 mm were cast using UHPFRC with the compressive strength of 160-190 MPa. The experimental parameters were the shear span to effective depth ratio, the volume fraction of steel fibres, and the presence or absence of prestress. The failure mode, indicating tensile failure in the web of the beam, was accompanied by fibre pull-out along the major diagonal crack. The test results indicated that the first cracking and ultimate shear strengths increased as the volume fraction of steel fibres increased. The ultimate shear strength decreased as the shear span to effective depth ratio increased. The increase in ultimate shear strength resulted from the instability of arch action at the shear span to effective depth ratio. In addition, the ultimate shear strength of prestressed beams increased compared with that of non-prestressed beams. The test results of this study provide valuable data that can be used in future studies to develop computational models of the shear behaviour of UHPFRC.