Rate effect in inclined fibre pull-out for smooth and hooked-end fibres: a numerical study

Abstract

Based on a numerical model to simulate the static behaviour of a smooth fibre extracted from a cementitious matrix, a rate dependent friction law, widely used in earthquake engineering for steady-state slip phenomena, is proposed to capture the rate effect observed in dynamic pull-out tests for both smooth and hooked-end fibres. After calibrating the friction coefficients with the experimental results of smooth fibres, the model is subsequently applied to predict the pullout behaviour of both smooth and hooked-end fibres at different inclination angles (0 • , 30 • and 60 • ) loaded at three different velocities (0.01, 0.1 and 1 mm/s). The global tendency of all the pull-out curves was captured, fibre's cross sectional deformations were also reproduced remarkably well. Moreover, the developed model helps to cast light on the different mechanisms related to the pull-out process.

Effect of the displacement rate and inclination angle in steel fiber pullout tests

“…On the other hand, the smooth fiber slips with a whole fiber-concrete contact, hence the frictional forces decrease slowly. This observation was corroborated by Poveda et al (2019), who developed a numerical model aimed to simulate the effects observed in inclined smooth and hooked-end fibers pulled out at different displacement rates. In their study, they compared a pulled out hooked-end fiber with one obtained by the numerical model and they observed the threepoint contact mechanism of the hooked-end fiber.…”

Propagation Speed of Dynamic Mode-I Cracks in Self-Compacting Steel Fiber-Reinforced Concrete

“…The zones without expected fracture are represented as four-node solid elements, whereas the crack is simulated as pairs of contact elements with cohesive nature in traction. The model is implemented in the commercial software Ansys, similar to the work of Poveda et al [ 31 ]. The experimental impact loads are used as input data for beams impacted at 1.77 and 2.66 m/s.…”

“…A typical mesh used in the simulations is illustrated in Figure 15 a, where the points at the central segment are marked out for the crack speed. It needs to be pointed out, the mesh-dependency issue has been thoroughly studied previously [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], and it has been concluded that with a mesh size commensurate with that of the maximum aggregate size (or the representative length at the mesoscale), the numerical model based on the cohesive theories of fracture is capable of produce mesh-independent results. Since all three types of material PA, PB and PC are considered homogeneous, the short steel fibers were 13 mm in length, the mesh size of 7.5 mm adopted in Figure 15 a can indeed produce mesh-independent results.…”

A novel analytical framework for assessing the impact response of SFRC beam

“…On the other hand, based on the experimental study performed by Ulzurrun et al [11], it was observed that by increasing the loading rate (height of impactor), the susceptibility of fiber rupture increases. This can be justified by the increase of the friction coefficient with the slip rate in the fiber pullout mechanism [44] and the higher stiffness response of the surrounding concrete matrix when submitted to higher pressure rate of due to fiber pullout, mainly by inclined fibers toward the crack plane, [45]. The fiber reinforcement performance depends on the strain rate, the geometry and the tensile strength of the fiber, [11].…”