0000000001062198
AUTHOR
Maria Concetta Oddo
A numerical study on the effect of the interface material model on the tensile behaviour of FRCM strips
Fibre Reinforced Cementitious Matrix (FRCM) composites are becoming increasingly popular for strengthening masonry structures for which the compatibility of the inorganic matrix with the chemical and physical properties of the support makes it advantageous to adopt such systems. However, despite the large use of FRCMs for strengthening applications, the characterization and modelling of the mechanical response in tension of these systems is an open issue. In fact, the constitutive tensile law of the composite shows to be affected by different variables, such as the clamping system adopted during tensile test, the gauge length used for recording strains, the monitoring of the number of yarns…
Numerical modelling of the tensile behaviour of BFRCM strips
This paper aims at investigating the tensile behaviour of basalt fibres on cementitious matrix for the strengthening of masonry structures. The use of Basalt Fibre Reinforced Cementitious Matrix (BFRCM) is favourably considered by the scientific community because it represents a natural composite material with high compatibility with stone and masonry substrate. The study is developed through the generation of Finite Element (FE) models capable of reproducing the tensile behaviour of BFRCM strips with different number of layers of grid. For the scope, the micro-modelling approach is adopted assuming different levels of detail for the simulation of the interface constitutive behaviour. Fibre…
Effect of corner over-reinforcing strips on the compressive behaviour of TRM confined masonry columns
Several recent works studied the efficiency of inorganic matrix composites, namely Textile Reinforced Mortar (TRM) or Fabric Reinforced Cementitious Matrix, for enhancing the strength and shortening capacity of masonry columns subjected to axial load. Literature studies were addressed to study the great number of variables involved in the problem, such as the nature and the grade of mortar, the strength of the fabric, the number of reinforcing layers, the type, the arrangement and the strength of the masonry, and helped to draw the first technical guidelines for practitioners and designers. All the experimental works highlighted that the actual performance of TRM confinement in masonry memb…
Performance of two innovative stress sensors imbedded in mortar joints of new masonry elements
Abstract Many historical cities enjoy the presence of masonry buildings with inestimable historical, artistic and cultural value. Old masonry buildings often suffer structural deficiencies, design faults and materials aging process. In recent years, many researchers focused their attention on the opportunities that structural health monitoring (SHM) can ensure for the health state of existing masonry structures, where damage can be difficult to be promptly predicted, pontentially causing abrupt collapses, with high risks for the community. This paper presents an experimental study on the effectiveness of two types of stress sensor for SHM of new masonry elements. Ceramic piezoelectric senso…
STATE OF THE ART ON BOND BETWEEN FRCM SYSTEMS AND MASONRY/CONCRETE SUBSTRATE: DATABASE ANALYSIS AND IMPROVED MODELS
The use of the Fabric Reinforced Cementitious Mortars (FRCMs) is nowadays a promising solution for the strengthening of both reinforced concrete and masonry structural elements. The application consists of a bond-dependent face-to-face plastering of an open grid or mesh by means of an inorganic-based matrix, i.e. a cement-based mortar. The main advantage of such a strengthening technique is the good compatibility with different types of substrates since the most suitable matrix can be selected focusing on the most similar breathability and stiffness. On the other side, the strengthening efficiency could be over-estimated if the potential bond failure is neglected. The FRCM-bond behaviour de…
Masonry columns confined with fabric reinforced cementitious matrix (FRCM) systems: A round robin test
Abstract The conservation and the preservation of existing masonry buildings, most of them recognized as cultural heritage, require retrofitting techniques that should reduce the invasiveness and assure reversibility and compatibility with the substrate. In this perspective, the strengthening system should be able to improve the bearing capacity of the structural member and, at the same time, to assure mechanical and material compatibility. The use of Fabric Reinforced Cementitious Matrix (FRCM) composites is now recognized to be suitable for these purposes. Indeed, the inorganic matrix has comparable properties with respect to the existing historical mortars while the fabric has relevant t…
Constitutive Numerical Model of FRCM Strips Under Traction
In this paper, the tensile behavior of Fiber Reinforced Cementitious Matrix (FRCM) strips is investigated through Finite Element (FE) models. The most adopted numerical modeling approaches for the simulation of the fiber-matrix interface law are described. Among them, the cohesive model is then used for the generation of FE models which are able to simulate the response under traction of FRCM strips tested in laboratory whose results are available in the technical literature. Tests on basalt, PBO and carbon coated FRCM specimens are taken into account also considering different mechanical ratios of the textile reinforcement. The comparison between FE results and experimental data allows val…
Formulation of a truss element for modelling the tensile response of FRCM strips
Modelling the tensile behaviour of Fabric Reinforced Cementitious Matrix (FRCM) is not a straightforward task due to the inner complexity of the mechanics of this kind of composite materials. In fact, after that the matrix is cracked, the compatibility between the fibre and the surrounding mortar is lost and the system behaves as two separate elements connected by a brittle interface. For this reason, several research studies proposed computational approaches for evaluating the tensile behaviour of FRCM composites, usually referring to brick-based 3D Finite Element Models (FEM) or to complex numerical procedures. This paper shows the formulation of a simplified coupled truss element for mod…
Advances in experimental characterization and modelling of FRCM composites for structural retrofitting
Questa tesi presenta i risultati di una campagna sperimentale incentrata sulla caratterizzazione della trazione dei basalt e glass FRCM e della caratterizzazione del legame di aderenza composito-Calcarenite. Il lavoro sperimentale è completato dalla proposta di due modelli numerici sia per prove di trazione che per quelle di aderenza. L'indagine sperimentale è stata condotta considerando l'influenza di diversi rinforzi, matrici e metodi di prova. I risultati sperimentali consentono di valutare l'effetto della malta sulle curve sforzo-deformazione, la resistenza, la duttilità e le modalità di crisi. Inoltre, la tesi fornisce un importante contributo per valutare l'influenza di diversi metodi…
Constitutive Models for the Tensile Behaviour of TRM Materials: Literature Review and Experimental Verification
In recent years, the scientific community has focused its interest on innovative inorganic matrix composite materials, namely TRM (Textile Reinforced Mortar). This class of materials satisfies the need of retrofitting existing masonry buildings, by keeping the compatibility with the substrate. Different recent studies were addressed to improve the knowledge on their mechanical behaviour and some theoretical models were proposed for predicting the tensile response of TRM strips. However, this task is complex due to the heterogeneity of the constituent materials and the stress transfer mechanism developed between matrix and fabric through the interface in the cracked stage. This paper present…
Experimental Investigation on Innovative Stress Sensors for Existing Masonry Structures Monitoring
Historical masonry structures often suffer gradual deterioration that in many cases can compromise the safety levels and the operating conditions of the buildings. In this context, Structural Health Monitoring (SHM) is an effective tool for the prediction of the structural behaviour and the state of conservation of buildings. Although many monitoring systems have recently been proposed, there is a lack of practical application of low-cost systems. This paper presents an experimental study based on the use of two innovative stress sensors—capacitive stress sensor and ceramic stress sensor—for the monitoring of existing masonry elements. In order to reproduce the actual conditions of onsite m…
Numerical Modelling of the Constitutive Behaviour of FRCM Composites through the Use of Truss Elements
The modeling of the mechanical behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites is a difficult task due to the complex mechanisms established at the fibre-matrix and composite-support interface level. Recently, several modeling approaches have been proposed to simulate the mechanical response of FRCM strengthening systems, however a simple and reliable procedure is still missing. In this paper, two simplified numerical models are proposed to simulate the tensile and shear bond behavior of FRCM composites. Both models take advantage of truss and non-linear spring elements to simulate the material components and the interface. The proposed approach enables us to deduce the …