The Role of Interface Parameters for the Accurate Numerical Modeling of the Mechanical Behavior of TRM Composites

The preservation and seismic risk mitigation of unreinforced masonry heritage remains a hot topic in structural research. Poor tensile strength, low ductility, irregular texture and lack of transverse connections are among the main causes of the high vulnerability and fragile behavior of historic masonry structures under seismic loading. Aiming to increase the resilience of the built environment to exceptional and unpredicted events, from past three decades the research community has been focusing its attention on investigating the best and durable retrofitting solutions to improve the structural capacity of masonry artefacts. Among the different techniques proposed in the technical literature, the Textile-Reinforced Mortar (TRM) is gaining a growing consensus. TRM composites are a combination of inorganic matrices and high-strength fibers. Thanks to its characteristics of vapor permeability, heat resistance, easy workability and compatibility with many substrate materials, TRM is currently recognized as the most appropriate reinforcement for historic masonry. Nevertheless, many uncertainties still arise about its mechanical behavior due to the complex interactions among its components (fiber and matrix) as well as between the TRM and the substrate to which it is applied. The present study aims to investigate from a numerical viewpoint the TRM three-dimensional behavior and, particularly, the key mechanical parameters necessary for the correct simulation and prediction of its response. This is achieved by replicating a wide multi-scale experimental campaign making use of 3D continuum numerical micro models where each component, including interfaces, is represented separately. The numerical simulation of the tests, carried out by employing consistent parameters throughout the modeling scales, brought to light novel knowledge concerning the minimum number of experiments needed to properly model the behavior of TRM composites.