Characterization of Textile-Reinforced Mortar: State of the Art and Detail-Level Modeling with a Free Open-Source Finite-Element Code

Abstract

The research addressed in the paper is aimed at calibrating a numerical model developed by using a free open-source finite-element code for the assessment of the structural performances of historical masonry buildings strengthened using the textile-reinforced mortar (TRM) technique. TRM is a near-surface-mounted system, which couples inorganic matrices with fiber-based textile or meshes. The main purpose is to develop a multiple-level numerical approach, starting with the detailed modeling of components and interfaces, followed by a computationally efficient intermediate level model, using layered elements, for the calibration of a lumped plasticity-based model suitable for the global analysis of structures. In this paper, the first research results are presented. In particular, a broad literature review concerning the mechanical characterization and analysis of TRM systems is collected. Then, the calibration of the numerical model, the validation through comparison with the results of experimental characterization tests available in the literature (tensile, shear bond, and in-plane shear tests) and a sensitivity analysis are reported. Nonlinear static analyses were performed, considering the nonlinearity of the composite material components and interfaces. The model was capable of accounting for the main parameters affecting the behavior of the composite material, such as the reinforcement ratio and orientation, the mortar characteristics and the wire-mortar interaction and proved to be a valid tool to investigate the optimization of TRM applicative details.

Masonry elements strengthened through Textile-Reinforced Mortar: application of detailed level modelling with a free open-source Finite-Element code

“…1e). The main features of these tests and the main results have already been resumed and commented in a recent paper [7], to which it is remanded for further insights. However, it's important to point out that different types of CRM failures were detected, namely the tensile rupture of yarns, the debonding of yarns from the mortar matrix and the debonding of the mortar from the masonry substrate.…”

“…Differently, the absence of shear bond in the point interfaces (IP), governing the yarn-yarn interaction, did not show any alteration in the curve trend, even though the failure point was anticipated. This difference is explained by considering the dominant role of the line interfaces against the yarn slippage, in respect to the less influent role of the point interfaces (as already emerged in the numerical study on pull-off tests performed in [7]). The no shear bond assumption at the mortar-masonry interface (IF) did not allow the collaboration between the two layers and, thus, the benefic damage diffusion of the reinforcement; therefore, the resistance decay occurred faster.…”

“…for the GFRP yarns. An elastic-brittle behavior in tension was assumed for the yarns (OOFEM material model Idm1), with parameters already set in [7] on the basis of experimental direct tensile tests on single yarns (Table 5). Differently, a Concrete-Damage Plasticity model [18], accounting for both cracking and crushing (OOFEM material model Con2dpm), was set for the mortar (Table 6), in accordance to the results experimental characterization tests performed on mortar cylinders (compression tests and indirect tensile tests).…”

“…Face-to-face plane interfaces (IntElSurfTr) were introduced to connect the mortar coating to the masonry substrate. All the interfaces (Table 7) were governed by a tangential bond-slip law (bondceb), whose parameters were previously set on the basis of experimental tests, as detailed specified in [7]. In particular, pull-out tests of GFRP yarns from the mortar coating, for the line-to-line interfaces, shear tests on mesh nodes, for point-to-point interfaces, and shear-bond tests on CRM coupons applied on masonry wallets, for the face-to-face interfaces.…”

“…Firstly, the effort focused on the mechanical characterization of TRM [7], with a deep analysis of the state of the art on the topic and the calibration and validation of the detailed level modelling on the basis of some experimental tests on TRM coupons available in the literature (pull-out tests, tensile tests, shear bond tests and in-plane shear tests). As a continuation of the study, the present paper deals with the application of the detailed level modelling on TRM strengthened masonry elements.…”