ABSTRACT
The determination of post cracking direct-shear capacity of UHPC reinforced with steel fibers (UHPFRC) is crucial for predicting the ultimate capacity and the deformation behavior of structural members subjected to shear and torsional forces. For the sake of determining the post cracking shear capacity, experimental investigations on small size notched UHPFRC prisms were carried out. Two volumetric ratios of steel fibers were used in the test program, which are 0.5% and 0.9%. Steel fibers having length, diameters and tensile strength of 17 mm, 0.15 mm and 2500 MPa respectively were used. At first, axial tensile force was applied to the UHPC prism to introduce a crack with a desired crack width, thereafter shear force was applied parallel to the faces of the introduced crack. Diagrams of the post cracking shear stress against shear displacement were plotted and are presented in this paper. Test results showed that the post cracking shear capacity increases as the crack width decreases. Several shear transmission mechanisms were noticed during the conduction of the test program. Average curves to describe the degradation of the shear strength and stiffness are also presented.
