Enhanced Computational Modelling of the Fracturing Behavior in CRM Single Lap Shear Tests

Among the most common materials for resilient building construction and strengthening repair, composite-reinforced mortars (CRMs) have gained an increased attention, due to the enhanced durability, strength, and performance of cementitious materials involving various kinds of fibers, such as glass, carbon or basalt, within the cement matrix. At the same time, such innovative materials are reversible and sustainable, and can be easily applied on irregular substrates, and wet supports providing better performances at high temperature. In this context, the interfacial behavior of CRM-to-substrate systems represents a crucial aspect that must be studied to ensure the resilience and durability of strengthened structures, as increasingly investigated for direct single-lap or double-lap tests in a theoretical, computational and experimental sense. According to the main experimental findings from the existing literature on single-lap shear tests, this work analyses computationally the mixed-mode interfacial response of CRM-to-substrate single-lap shear specimens, as provided by the concrete damaged plasticity and cohesive crack models within a finite element environment. The matrix properties of the selected specimen are characterized by two different analytical approximations, namely, an exponential law available from literature, and a novel polynomial approximation, which is adequately calibrated for an accurate modelling of the softening response. The proposed model is validated systematically for different input parameters such as, the fiber stiffness, the fiber-matrix interfacial strength, and the specimen geometry, with an accurate prediction of the damage location, initiation and development, both from a local and global standpoint. The main results of this numerical work could provide useful insights for the design of CRM reinforcements and their potential applications, in an inexpensive way, instead of more costly experimental investigations.