Numerical Approach to Determine the Resistance of Threaded Anchors in Ultra-High-Performance Fiber-Reinforced Cementitious Composite

Due to their relatively high tensile strength and dense matrix, UHPFRCs have proven to be a highly effective building material for both strengthening existing reinforced concrete structures and constructing new ones. In both cases, the use of fasteners is prevailing, with threaded anchors being frequently employed. The thicknesses of structural components made of UHPFRCs are relatively thin, i.e., at least 30 mm, typically 50 to 100 mm, and exceptionally 100 to 200 mm. Therefore, the aim is to use fasteners with short anchorage lengths. In this study, the structural behavior of a short threaded anchor with a 20 mm diameter and an embedment length of 50 mm (2.5 Ø) in a UHPFRC is investigated using non-linear finite element models. The UHPFRC is assumed to exhibit tensile strain-hardening behavior, with tensile strengths of 7 MPa and 11 MPa, respectively. The modeled anchor was subjected to a continuously increasing uniaxial pull-out force. The results indicate that the fracture mechanism of threaded anchors in UHPFRCs is primarily characterized by the formation of a tensile membrane within the UHPFRC, which acts as the main resisting element against the pull-out force. Additionally, the influence of the UHPFRC’s tensile properties on the pull-out behavior and ultimate resistance of the threaded anchors was determined.