Academic literature on the topic 'Textile-reinforced mortars'

Among masonry buildings characterized by a complex architecture, a significant portion is represented by heritage buildings. A significant seismic vulnerability is due to the presence of thrusting elements like as arches and vaults. Their ultimate capacity can be improved by means of several strengthening techniques. However the advantages of using Textile Reinforced Mortars (TRM) are well highlighted in the scientific literature.The present work focuses on ultimate behaviour of masonry barrel vaults, in the framework of incremental analysis, including the strengthening effect. The analytical model is compared in terms of ultimate capacity and failure mode with a full scale masonry barrel vault dynamically tested. After the first tests, the vault has been strengthened with Textile Reinforced Mortar (TRM) and tested again.

This work presents a method of strengthening concrete structures based on textiles of high strength and mortars. The combination of textiles and mortars produces a new composite material with cementitious matrix. This material can be used for the reinforcement of concrete beams under bending loads. We tested several combinations of fibers: glass, Poliparafenil Benzobisoxazol (PBO), steel and carbon fibers with mortar and we used them to reinforce precast concrete beams. All the specimens were tested with a four-point load test. We discuss the performance of the specimens and we compare the ultimate results with the formulae from FRP codes.

Sustainable maintenance of existing steel-reinforced concrete structures becomes more important. Using non-reinforced sprayed mortar to maintain these structures often leads to cracks in this repair layer due to the alteration of crack widths in the ordinary structure. The water impermeability as well as the durability of the sprayed mortar will be reduced due to the described cracks. This presentation shows a solution for the described problem. The use of carbon yarns with a special inorganic coating as reinforcement in sprayed mortars leads to a self-healing of the arising cracks. Due to the inorganic coating applied on carbon yarns the excellent bond between mortar and yarn results in a fine distributed crack image with crack width below 0.1 mm. It is shown that these cracks heal themselves. Consequently we can provide a mainly mineral protection layer for existing steel reinforced concrete structures which is impermeably to water based solutions. The presentation focuses on the material development and characterization.

The need for retrofitting existing masonry structures is progressively becoming more important due to their continuous deterioration or need to meet the current design requirements of Eurocodes. Textile-Reinforced Mortar (TRM) composite systems have emerged as a sustainable repair methodology suitable for structure retrofitting. Nevertheless, their mechanical performance is still far from being fully investigated. This paper presents an experimental study on the tensile and bond behaviors of a new mortar-based composite consisting of mineral additives, blended cement mortar, and stainless-steel grid. Three different mineral additives (silica fume, fly ash, and blast furnace slag), in binary and ternary systems were used. The experimental study included uniaxial tensile coupon testing on composite specimens and bond tests on composite material applied to clay-brick substrate. The results obtained with the different textile-reinforced cement-based mortars were compared and are discussed here. It was found that, for mortar formulations containing mineral additives—such as fly ash or blast-furnace slag—with high tensile and bond strengths, an adequate adherence between the constituents was obtained. The developed mortar presents mechanical performances equivalent to traditional mortars without additives. The study contributes to the existing knowledge regarding the structural behavior of TRM and promotes the development of a low impact carbon cementitious matrix.

Textile Reinforced Mortars (TRM) include a series of innovative strengthening systems suitable for conservation interventions since inorganic matrixes, instead of polymeric resins, are employed. Recent research supported the definition of guidelines on testing methods for TRM systems applied to masonry, but further investigation is needed to clear out the role played by the numerous factors affecting the strengthening capacity. In this study, an experimental campaign on basalt-fibre TRM systems was carried out. A series of tensile and single-shear bond tests are compared. Samples differ for fibre reinforcement ratio, textile layout and the number of textile layers, while the lime-based mortar matrix is the same for all specimens. For tensile tests, results show that, after a mortar-cracking phase, a third, substantially linear phase, during which the textile response is dominant, occurred for specimens failed both for textile tensile rupture and textile slippage. For shear bond tests, results showed that increasing the reinforcement ratio tightening textile mesh is not as beneficial as increasing textile layers, i.e. active bond surfaces.

Application of lime-based textile-reinforced mortars (TRMs) for strengthening of masonry structures have received a growing attention in recent years. An extensive effort has been devoted to understanding of the performance of these composites and their effectiveness in improving the seismic safety of existing masonry structures. Nevertheless, several aspects regarding the durability and mechanics of these composites still remain unknown. This letter is an effort on highlighting those aspects considering both experimental and numerical modelling approaches.

It is clear that the fiber-to-mortar bond behavior plays a major role on the performance of Textile Reinforced Mortars (TRMs) used for strengthening of existing structures. This aspect, however, has been only the subject of few studies and require further attention.This paper presents an analytical model for extraction of the textile-to-‎mortar bond-slip laws from pull-out tests. The ‎objective is to ‎characterize the parameters that ‎influence the ‎pull-out behavior of TRM ‎systems. ‎In the formulation of the ‎pull-out model, a ‎modified approach ‎based ‎on a mathematical model by Naaman ‎is applied. Firstly, based on ‎the ‎experimental ‎results, a relationship between the bond shear stress and the ‎relative slip ‎along the fiber-mortar ‎interface is obtained. Then, based on the ‎shear stress-slip law, the ‎boundary conditions, equations ‎of equilibrium, and ‎the equation of ‎compatibility and hooke’s ‎law, the bond response ‎between ‎textile and mortar is predicted and modeled.

Rammed earth constructions are widely found worldwide, but they are endangered by their recognised high seismic vulnerability. As compatible and affordable reinforcement approaches are important requirements for these constructions, a strengthening solution based on low cost textile reinforced mortars (LC-TRM) is proposed here, within the framework of a large research project. This paper presents the results of an experimental program aimed at characterising low cost meshes available in the market (glass fibre, plastic, metallic and nylon) and at assessing possible mortars (unstabilised earth, stabilised earth, commercial earth and cement-based) capable of integrating the LC-TRM strengthening system. In general, the results obtained seem to indicate that the glass fibre meshes and the earth mortar are good options.

An innovative strengthening technique is applied for the first time in this study to provide flexural strengthening in two-way reinforced concrete (RC) slabs supported on edge beams. The technique comprises external bonding of textiles on the tension face of RC slabs through the use of polymer-modified cement- based mortars. The textiles used in the experimental campaign comprised fabric meshes made of long stitch-bonded fibre rovings in two orthogonal directions. The specimens measured 2 x 2 m in plan and were supported on hinges at the corners. Three RC slabs strengthened by textile reinforced mortar (TRM) overlays and one control specimen were tested to failure. One specimen received one layer of carbon fibre textile, another one received two, whereas the third specimen was strengthened with three layers of glass fibre textile having the same axial rigidity (in both directions) with the single-layered carbon fibre textile. All specimens failed due to flexural punching. The load-carrying capacity of the strengthened slabs was increased by 26%, 53%, and 20% over that of the control specimen for slabs with one (carbon), two (carbon) and three (glass) textile layers, respectively. The strengthened slabs showed an increase in stiffness and energy absorption. The experimental results are compared with theoretical predictions based on existing models specifically developed for two-way slabs and the performance of the latter is evaluated. Based on the findings of this work the authors conclude that TRM overlays comprise a very promising solution for the strengthening of two-way RC slabs.

The effectiveness of a new structural material, namely textilereinforced mortar (TRM), was investigated experimentally in this study as a means of confining old-type reinforced concrete columns with limited capacity due to bar buckling or due to bond failure at lap splice regions. Comparisons with equal stiffness and strength fiber-reinforced polymer (FRP) jackets allow for the evaluation of the effectiveness of TRM versus FRP. Tests were carried out on full scale non-seismically detailed RC columns subjected to cyclic uniaxial flexure under constant axial load. Thirteen cantilever-type specimens with either continuous longitudinal reinforcement (smooth or deformed) or lap splicing of longitudinal bars at the floor level were constructed and tested. Experimental results indicated that TRM jacketing is quite effective as a means of increasing the cyclic deformation capacity of old-type RC columns with poor detailing, by delaying bar buckling and by preventing splitting bond failures in columns with lap spliced bars. Compared with their FRP counterparts, TRM jackets used in this study were found to be equally effective in terms of increasing both the strength and deformation capacity of the retrofitted columns. From the response of specimens tested in this study, it can be concluded that TRM jacketing is an extremely promising solution for the confinement of reinforced concrete columns, including poorly detailed ones with or without lap splices in seismic regions.

There is a growing interest for strengthening and upgrading existing concrete structures both in seismic and non-seismic regions due to their continuous deterioration as a result of aging, degradation induced environment conditions, inadequate maintenance, and the need to meet the modern codes (i.e. Eurocodes). Almost a decade ago, an innovative cement-based composite material, the so-called textile-reinforced mortar (TRM), was introduced in the field of structural retrofitting. TRM comprises high-strength fibres in form of textiles embedded into inorganic matrices such as cement-based mortars. TRM offers well-established advantages such as: fire resistance, low cost, air permeability, and ability to apply on wet surfaces and at ambient of low temperatures. It is well known that the effectiveness of any external strengthening system in increasing the flexural capacity of concrete members depends primarily on the bond between the strengthening material and member’s substrate. This PhD Thesis provides a comprehensive experimental study on the bond behaviour between TRM and concrete substrate and also provides a fundamental understanding of the flexural behaviour of RC beams strengthened with TRM. Firstly, the tensile properties of the textile reinforcement were determined through carrying out tensile tests on bare textiles, and TRM coupons. Secondly, the bond behaviour between TRM and concrete substrates both at ambient and, for the first time, at high temperature was extensively investigated. A total of 148 specimens (80 specimens tested at ambient temperature and 68 specimens tested at high temperatures) were, fabricated, and tested under double-lap shear. Parameters investigated at ambient temperature comprised: (a) the bond length; (b) the number of layers; (c) the concrete surface preparation; (d) the concrete compressive strength; (e) the textile surface condition; and (f) the anchorage through wrapping with TRM jackets. Whereas, the parameters examined at high temperatures included: (a) the strengthening systems (TRM versus FRP); (b) the level of temperature at which the specimens were exposed; (c) the number of FRP/TRM layers; and (d) the loading conditions. The results of ambient temperature tests indicated that the bond at the TRM-concrete interface is sensitive to parameters such as: the number of layers, the textile surface condition, and the anchorage through wrapping with TRM. On the other hand, the results of high temperature tests showed that TRM exhibited excellent bond performance with concrete (up to 400 0C) contrary to FRP which practically lost its bond with concrete at temperatures above the glass trainset temperature (Tg). The flexural strengthening of RC beams with TRM at ambient and for the first time at high temperature was also examined carrying out 32 half-scale beams. The examined parameters were: (a) the strengthening system (TRM versus FRP); (b) the number of layers; (c) the textile surface condition; (d) the textile fibre material; (e) the end-anchorage system of the external reinforcement; and (f) the textile geometry. The results of ambient temperature tests showed that TRM was effective in increasing the flexural capacity of RC beams but its effectiveness was sensitive to the number of layers. Furthermore, a simple formula used for predicting the mean FRP debonding stress was modified for predicting the TRM debonding stress based on the experiment data available. The results of high temperature tests showed that TRM maintained an average effectiveness of 55%, of its effectiveness at ambient temperature, contrary to FRP which has totally lost its effectiveness when subjected to high temperature. Finally, a stress reduction factor of TRM flexural effectiveness (compared to its ambient effectiveness) when subjected to high temperature was also proposed.

The issue of upgrading existing structures is of great importance due to their deterioration (ageing, environmental induced degradation, lack of maintenance, need to meet the current design requirements). Recently, an innovative structural material, the so-called Textile-Reinforced Mortar (TRM), was successfully developed for structural retrofitting of deficient masonry and concrete structures. TRM is an advanced sustainable material which offers well-established advantages (good behaviour at high temperature, compatibility to concrete or masonry substrates material high strength to weight ratio, corrosion resistance, ease and speed of application, minimal change of cross section dimensions) at a low-cost and over the last decade it has been reported in the literature that TRM is a very promising alternative to the FRP (Fibre Reinforced Polymers) retrofitting solution. This study evaluates the use of TRM jacketing for shear strengthening of Reinforced Concrete (RC) beams. First of all, the materials used for strengthening are described and the tensile and shear behaviour of textiles was characterised through tensile and picture-frame tests, repsectively. Moreover, the tensile properties of TRM composite material are experimentally obtained through bell-shaped TRM coupons. Shear strengthening of RC beams was extensively studied carrying out 55 medium-scale rectangular beams and 14 full-scale T-beam ends. The key investigated parameters on medium-scale rectangular beams comprise: (a) the strengthening system (TRM versus FRP), the (b) strengthening configuration, (c) the number of layers, (d) the external reinforcement ratio, (e) the textile material mesh characteristics, (f) the shear-span-to depth ratio and (g) the optimisation of the textile geometry. It was concluded that TRM was very effective on increasing the shear resistance of RC beams but its effectiveness was sensitive to parameters such as the strengthening configuration, the number of layers and the textile characteristics. Experimental work was also conducted on full-scale T-beams focused on the use of a novel end-anchorage system comprising textile-based anchors to delay or prevent the debonding of TRM jacket. In particular, the anchorage percentage of the U-jacket, the number of layers, the textile material, the textile geometry and the strengthening system (TRM versus FRP jackets) were the main investigated parameters. U-shaped TRM jackets significantly increased the shear capacity of full-scale T-beams, whereas the use of textile-based anchors improved dramatically the effectiveness of the TRM jackets. A simple design model was also proposed to calculate the contribution of anchored TRM jackets to the shear capacity of RC T-beams. The behaviour of TRM at high temperature used for shear strengthening of both medium-scale and full-scale beams was studied for the first time through demanding tests in which loading and high temperature were simultaneously applied. Based on the experimental results, TRM jacketing remained very effective at high temperature, whereas the effectiveness of side-bonding and U-wrapping FRP jacketing was reduced nearly to zero when subjected at temperatures above the glass transition temperature (Tg). A stress reduction factor for TRM and FRP systems was also introduced to take into account the decrease in the effectiveness of both TRM and FRP jacket due to explosion of specimens to high temperature. Finally, design models for the prediction of the contribution of the TRM jacket to the total shear resistance were proposed for each failure mode and verified with the available experimental data.

Nei paesi dell’area mediterranea, come Italia e Spagna, numerosi edifici, sono realizzati in muratura, e questo li rende vulnerabili alle azioni sismiche. I terremoti avvenuti in passato, hanno permesso, attraverso lo studio dei danneggiamenti prodotti, di comprendere le vulnerabilità di questi edifici e anche di valutare l’effettivo miglioramento o peggioramento delle diverse tecniche adoperate nel corso degli anni. Nel corso degli ultimi anni ,diverse tecniche innovative sono state sviluppate, tra cui l’uso di TRM (Textile Reinforced Mortar), risulta essere una delle migliori scelte data la reversibilità dell’intervento e la buona compatibilità con la muratura. Nonostante ciò, al momento non sono disponibili procedimenti analitici, per la valutazione dell’ incremento di resistenza a taglio di strutture rinforzate con TRM. L’obiettivo di questa tesi è di analizzare il cambio di comportamento di provini testati a compressione semplice e diagonale, rinforzati con TRM. I risultati ottenuti dalla campagna sperimentale, serviranno alla calibrazione di modelli numerici realizzati in SAP2000. I modelli, basati solo sull’uso di elementi non lineari “shell-layered”, vogliono costituire un modello semplice, riutilizzabile dal progettista per l’analisi di strutture più complesse. Successivamente i dati raccolti durante la campagna sperimentale sono stati utilizzati per la ricerca di formule analitiche, che permettano di valutare l’incremento della resistenza a taglio di strutture rinforzate. I provini rinforzati sono in grado di sorreggere un carico ultimo pari al doppio dei non rinforzati, con un aumento della deformazione orizzontale al limite elastico e della capacità di dissipazione di energia. Il rinforzo in TRM è quindi in grado di migliorare il comportamento di strutture in muratura soggette ad azioni orizzontali, ed i modelli creati con SAP2000, si sono dimostrati validi per simulare il comportamento di strutture in muratura rinforzate e non rinforzate.

Textile composite materials with cement based adhesive have been developed recently by the construction industry for strengthening of concrete structures. Textile reinforced mortar (TRM) materials are known to be more compatible with the concrete substrate and can provide a substantial gain in compressive strength and deformability of the structure, as well as a better performance at high temperatures and during fire when compared to other strengthening materials such as fibre reinforced polymer. In this study, the effect of select physical (thickness) and mechanical (modulus of elasticity) properties of different types of TRM reinforcement (carbon, poly-phenylene-2,6-benzobisoxazolem (PBO), and steel fibres) with different reinforcement ratio has been investigated on the ensuing flexural performance of RC beams, by means of a finite element (FE) model. The response variables were the beam’s load carrying capacity, mid-span deflection, effective stiffness, and failure mode. Results of the numerical simulation and factorial design analysis indicated that the application of TRM sheets can be effective in strengthening the RC beams with a statistical significance of α=5%, under all of the above-mentioned response variables, in some cases as much as 109% when compared to the unstrengthend RC beam.
Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate

Dans le domaine du renforcement et/ou de la réparation des structures en béton armé par des matériaux composites à l'aide de la méthode du collage extérieur au moyen d'un adhésif époxy, une des préoccupations de la communauté scientifique est l'intégrité structurelle de ce système dans le cas d'incendie dans lequel la haute température est une caractéristique essentielle et peut atteindre jusqu'à 1200°C. Ce travail de recherche est axé sur le comportement thermomécanique à très haute température des matériaux composites [un composite à base de polymère carbone/ époxy (Carbon Fiber Reinforced Polymer- CFRP), un composite textile/ mortier cimentaire (Textile Reinforced Concrete- TRC) et un adhésif à base d'époxy]. L'évolution des propriétés mécaniques et d'autres aspects mécaniques de ces matériaux composites avec la température a été caractérisée. Une nouvelle procédure expérimentale concernant la mesure de la déformation de l'éprouvette à l'aide du capteur laser est développée et validée. Une étude numérique et expérimentale a été réalisée dans le but de déterminer principalement la température à la rupture des joints « composite/ adhésif/ composite » sous les sollicitations mécaniques et thermiques. L'efficacité de la protection thermique de deux isolants [PROMASPRAY®T (produit commercial de la société PROMAT] et Isolant A (produit développé par le LGCIE site Tusset) a aussi été étudiée dans cette thèse. Enfin, une approche numérique, à l'aide du logiciel ANSYS, est utilisée afin de déterminer, de façon préliminaire et approximative, à l'échelle matériau, les propriétés thermiques des matériaux (composite textile/ mortier cimentaire -TRC et Isolant A)
In the area of the strengthening and/or the reparation of reinforced concrete structures with composites by means of the external bonding method using an epoxy adhesive, one of the preoccupation of the scientific community is the structural integrity of this system in the event of fire in which the high temperature is the essential feature et can reach up to 1200°C. This research focuses on the thermo-mechanical behavior of composite materials [carbon/epoxy adhesive composite (or carbon fiber reinforced polymer (CFRP), textile/cementitious mortar composite (or textile reinforced concrete (TRC)] and an epoxy-based adhesive. The evolution of mechanical properties and other mechanical aspects of these materials with the temperature has been characterized. A new experimental procedure concerning the measurement of sample strain by the laser sensor is developed and validated. An experimental and numerical study has been realized in order to mainly determine the temperature at the failure of "composite/adhesive/composite" joints under thermal and mechanical loadings. The effectiveness of the thermal protection of two insulators [PROMASPRAY®T (a commercial product of the PROMAT company and the insulator A (product developed by the LGCIE site Tuset)] has also been investigated in this PhD thesis. Finally, a numerical approach, using ANSYS software, is used to determine, in the preliminary and approximate way, at material scale, thermal properties of the materials [the textile reinforced concrete (TRC) and the insulator A]

La presente tesis tiene como finalidad demostrar que es posible la rehabilitación de un reservorio de agua de concreto armado apoyado con fisuras no estructurales usando Textile Reinforced Mortar (TRM). Para el desarrollo de la tesis, se eligió como muestra uno de los trece reservorios que figuran en el estudio para la ampliación y mejoramiento de los sistemas de agua potable y alcantarillado de los sectores 311, 313, 330, 310, 312, 314, 300, 307, 319, 324, y 301 Nueva Rinconada, distritos de San Juan de Miraflores, Villa María del Triunfo y Villa el Salvador. El reservorio seleccionado fue el R -6A, el cual tiene una antigüedad de aproximadamente 30 años y tiene una capacidad de 750 m3. Para identificar la zona donde se propone la rehabilitación del reservorio seleccionado, fue necesario identificar el origen de la falla, por lo que adicionalmente al diagnóstico obtenido del expediente técnico, se realizó la configuración estructural del reservorio con los datos obtenidos en campo. De este modo, los resultados hallados permitieron verificar que el diseño planteado hace más de 30 años cumplen con la normativa actual, comprobándose que las fallas que presenta el reservorio no son estructurales. Asimismo, los cálculos permitieron conocer la ubicación del área afectada, información que fue necesaria para elaborar la propuesta de rehabilitación con TRM y la alternativa seleccionada para la rehabilitación del muro del reservorio fue una matriz de mortero Sika Rep y una malla de refuerzo Sika Ward 350 G. En la presente tesis, se realizaron los ensayos correspondientes a este material compuesto y se plantea el procedimiento para la rehabilitación, así como las pruebas de calidad necesarias para garantizar el apropiado uso de esta tecnología en constante desarrollo.
This thesis is to demonstrate that it is possible to rehabilitate a supported reinforced concrete water reservoir with the presence of non-structural cracks using Textile Reinforced Mortar (TRM). For the development, one of the thirteen reservoirs that appear in the study for the expansion and improvement of the drinking water and sewerage systems of sectors 311, 313, 330, 310, 312, 314, 300, 307, was chosen as a sample. 319, 324, and 301 Nueva Rinconada, districts of San Juan de Miraflores, Villa María del Triunfo and Villa el Salvador. The selected reservoir is R -6A, which is approximately 30 years old and has a capacity of 750 m3. To propose the rehabilitation of the chosen structure, it was necessary to identify the origin of the failure, so in addition to the structural diagnosis obtained from the technical file of the profile, the structural configuration of the reservoir was obtained with the data taken in the field. In this way, the results found allowed to verify that the design proposed more than 30 years ago complies with the current regulations and it was verified that the failures that the reservoir presents are not structural. Likewise, the calculations allowed the location of the affected area to be known, information that was necessary to prepare the rehabilitation proposal with TRM. The alternative selected for the reservoir wall rehabilitation is the Textile Reinforced Mortar (TRM) system. In this thesis, the tests corresponding to this composite material were carried out and the procedure for rehabilitation is proposed, as well as the quality tests necessary to guarantee the appropriate use of this technology in constant development.
Tesis

The global tendency to apply sustainability criteria in most of productive fields, as well as, the limited durability and the pathologies that suffer the reinforced concrete elements, are aspects that directly affect the increasing necessity of strengthening this type of structures. Reinforced concrete beams are frequently subjected to bending and shear efforts. The evolution of strengthening techniques, that permit to increase the load bearing capacity in front this type of efforts, has consisted in the development of new technologies that maximise the velocity and ease the execution of the solution, minimising the time structures are out of service. In this way, the introduction of composite materials in construction has revolutionised the structural strengthening field. The textile-reinforced mortar (TRM) is a composite material that combines textiles, made of high strength tensile fibres, with cementitious matrix. The main characteristic of this material is that, unlike the techniques as fibre-reinforced polymer (FRP), it does not require the use of organic resins for its fabrication and application on structures. The present thesis has consisted in the analysis of the mechanical and structural behaviour of reinforced concrete beams strengthened against flexural and shear efforts using different types of TRM. To fulfil this aim, two main experimental campaigns have been carried out. In the first one, eleven full-scale beams, ten of them previously flexural strengthened with five different types of TRM, have been tested. In the second experimental campaign, nine reinforced concrete beams, eight of them shear strengthened with four different combinations of textiles and mortars, have been subjected to experimental tests. Before these main experimental campaigns, the mechanical behaviour of all materials used in the research has been characterised (that is concrete, steel, mortars, textiles and TRM). Moreover, an experimental approach, based on the flexural strengthening and testing of twelve precast beams, has been done. This campaign has allowed familiarising with the application of the reinforcement and obtaining results, from which, most appropriate combinations of textiles and mortars to use in main experimental campaigns have been chosen. Using the experimental data, two analytical studies, focused on the design of reinforced concrete beams flexural and shear strengthened with TRM, respectively, have been carried out. In both studies, initially, it has evaluated the prediction capacity of three analytical models included in design standards of FRP and TRM. For two of them, the formulation of the codes proposed by fib-Bulletin 14 and ACI 440.2R-08 has been adapted to the particular case of cementitious matrix reinforcements. The formulation according to ACI 549.4R-13 has been directly applied in the third. In the second part of the studies analytical models based on the reduction of mechanical capacities of the fibers have been carried out. These employed the experimental results obtained in the present research and the gathered from similar investigations. The results show that, in the case of TRM applied as a flexural reinforcement, the strengthening system is able to increase of 27.4% the beams capacity before the flexural yielding and 8.2% the ultimate bending capacity. This increase reaches 33.7% in the case of the shear strengthened reinforced concrete beams. On the other hand, the results of analytical studies indicate that models adapted from FRP standards present a better prediction capacity than the obtained with the code specifically developed for TRM reinforcements, which has performed significantly conservative. Finally, the proposed analytical models, based on the adjustment of the textile fibers properties, show a new conception for the design of TRM strengthening on reinforced concrete beams.
La tendencia global en aplicar criterios de sostenibilidad en la mayoría de ámbitos productivos, así como la limitada durabilidad y las patologías que sufren los elementos de hormigón armado, son aspectos que influyen directamente en la creciente necesidad de reforzar este tipo de estructuras. Las vigas de hormigón armado son elementos frecuentemente sometidos a esfuerzos de flexión y cortante. La evolución de las técnicas de refuerzo que permiten incrementar la capacidad resistente frente estas solicitaciones, ha consistido en el desarrollo de nuevas tecnologías que maximizan la velocidad/facilidad de ejecución de la solución y minimizan el tiempo que la estructura está fuera de servicio. En este sentido, la introducción de materiales compuestos en la construcción ha revolucionado el sector de los refuerzos estructurales. El textile-reinforced mortar (TRM) es un material compuesto que combina tejidos, hechos de fibras de resistencia a tracción elevada, y matrices de base cementítica. La principal característica de este material es que, a diferencia de técnicas como el fibre-reinforced polymer (FRP), no requiere de la utilización de resinas orgánicas para su fabricación y aplicación en las estructuras. La presente tesis ha consistido en el análisis del comportamiento mecánico y estructural de vigas de HA reforzadas a flexión y a cortante con diferentes tipos de TRM. Para lograr este objetivo, se han realizado dos campañas experimentales principales. En la primera de ellas, se han ensayado once vigas a escala real, diez de ellas reforzadas previamente a flexión con cinco tipos diferentes de TRM. En la segunda campaña, se han sometido a ensayo nueve vigas de HA, ocho de ellas reforzadas a cortante con cuatro combinaciones diferentes de tejidos y morteros. Antes de estas campañas principales, se ha caracterizado el comportamiento mecánico de todos los materiales utilizados, es decir, el hormigón, el acero, los morteros, los tejidos y el material compuesto TRM. Además, se ha realizado una campaña experimental de aproximación, basada en el refuerzo a flexión y ensayo de doce viguetas prefabricadas, que ha permitido la familiarización con la técnica de aplicación del refuerzo y la obtención de resultados, a partir de los cuales, se ha elegido las mejores combinaciones de tejidos y morteros a utilizar en las campañas experimentales principales. Utilizando los datos experimentales, se han realizado dos estudios analíticos enfocados al diseño de vigas de HA reforzadas a flexión y a cortante con TRM, respectivamente. En ambos estudios, inicialmente se ha evaluado la capacidad de predicción de tres modelos analíticos incluidos en normativas de FRP y TRM, adaptando la formulación de los códigos propuesta por fib-Bulletin 14 y ACI 440.2R-08 al caso particular de los refuerzos de matriz cementítica, y aplicando directamente la formulación propuesta por ACI 549.4R-13. En la segunda parte de los estudios, empleando los resultados experimentales obtenidos en el presente trabajo y los recopilados de investigaciones similares, se han desarrollado modelos analíticos basados en la reducción de las capacidades mecánicas de las fibras que componen los tejidos. Los resultados muestran que, en el caso del TRM aplicado como refuerzo a flexión, los especímenes logran incrementar en un 27,4% su capacidad previa a la plastificación, y en un 8,2% su capacidad última a flexión. Este incremento de prestaciones alcanza el 33,7% en el caso de las vigas de HA reforzadas a cortante. Por otro lado, los resultados del estudio analítico muestran que los modelos adaptados de las normativas de FRP presentan una mejor capacidad de predicción que el modelo desarrollado para el TRM, que se revela significativamente conservador. Por último, los modelos analíticos propuestos, basados en el ajuste de las propiedades de las fibras de los tejidos, muestran un nuevo enfoque para el diseño de refuerzos TRM en vigas de HA.
La tendència global a aplicar criteris de sostenibilitat en la majoria d’àmbits productius, així com la limitada durabilitat i les patologies que pateixen els elements de formigó armat, són aspectes que influeixen directament en la creixent necessitat de reforçar aquest tipus d’estructures. Les bigues de formigó armat són elements freqüentment sotmesos a esforços de flexió i tallant. L’evolució de les tècniques de reforç que permeten incrementar la capacitat resistent en front aquestes sol·licitacions, ha consistit en el desenvolupament de noves tecnologies que maximitzessin la velocitat/facilitat d’execució de la solució i minimitzessin el temps que l’estructura està fora de servei. En aquest sentit, la introducció de materials compostos en la construcció ha revolucionat el sector dels reforços estructurals. El textile-reinforced mortar (TRM) és un material compost que combina teixits, fets de fibres de resistència a tracció elevada, i matrius de base cementítica. La principal característica d’aquest material es que, a diferència de tècniques com el fibre-reinforced polymer (FRP), no requereix de la utilització de resines orgàniques per a la seva fabricació y aplicació a les estructures. La present tesi ha consistit en l’anàlisi del comportament mecànic i estructural de bigues de formigó armat reforçades a flexió i a tallant amb diferents tipus de TRM. Per a aconseguir aquest objectiu, s’han realitzat dues campanyes experimentals principals. En la primera d’elles, s’han assajat onze bigues a escala real, deu d’elles reforçades prèviament a flexió amb cinc tipus diferents de TRM. En la segona campanya, s’han sotmès a assajos nou bigues de formigó armat, vuit d’elles reforçades a tallant amb quatre combinacions diferents de teixits i morters. Abans d’aquestes campanyes principals, s’ha caracteritzat el comportament mecànic de tots els materials utilitzats, és a dir, el formigó, l’acer, els morters, els teixits i el material compost TRM. A més, s’ha realitzat una campanya experimental d’aproximació, basada en el reforç a flexió i assaig de dotze biguetes prefabricades, que ha permès la familiarització amb la tècnica de reforç i l’obtenció de resultats, a partir dels quals, s’han escollit les millors combinacions de teixits i morters a utilitzar en les campanyes experimentals principals. Utilitzant les dades experimentals, s’han realitzat dos estudis analítics enfocats al disseny de bigues de formigó armat reforçades a flexió i a tallant, respectivament. En ambdós estudis, inicialment s’ha avaluat la capacitat de predicció de tres models analítics inclosos en normatives de FRP i TRM, adaptant la formulació dels codis proposada per fib-Bulletin 14 i ACI 440.2R-08 al cas particular dels reforços de matriu cementítica, i aplicant directament la formulació proposada per ACI 549.4R-13. En la segona part dels estudis, emprant els resultats experimentals obtinguts en el present treball i els recopilats d’investigacions similars, s’han desenvolupat models analítics basats en la reducció de les capacitats mecàniques de les fibres que composen els teixits. Els resultats mostren que, en el cas del TRM aplicat com a reforç a flexió, els espècimens aconsegueixen incrementar en un 27,4% la seva capacitat prèvia a la plastificació, y en un 8,2% la seva capacitat última a flexió. Aquest increment de prestacions arriba fins el 33,7% en el cas de les bigues de formigó armat reforçades a tallant. Per altra banda, els resultats de l’estudi analític mostren que els models adaptats de les normatives de FRP presenten una millor capacitat de predicció que el model desenvolupat per al TRM, que es revela significativament conservador. Per últim, els models analítics proposats, basats en l’ajust de les propietats de les fibres dels teixits, mostren un nou enfoc per al disseny de reforços TRM en bigues de formigó armat

Αντικείμενο της παρούσας διατριβής αποτελεί η πειραματική διερεύνηση της συμπεριφοράς διατάξεων ενίσχυσης πλακοδοκών (Τ-δοκοί) οπλισμένου σκυροδέματος, σε τέμνουσα δύναμη με χρήση πλεγμάτων συνεχών ινών άνθρακα δύο διευθύνσεων 0°/90°, σε ανόργανη μήτρα κονιάματος με βάση το τσιμέντο (Ινοπλέγματα Ανόργανης Μήτρας). Η διεξαγωγή των πειραματικών δοκιμών γίνεται σε ανακυκλιζόμενη φόρτιση σταθερού βήματος (κύκλοι φόρτισης). Ζητούμενο της πειραματικής διαδικασίας είναι η διερεύνηση της αποτελεσματικότητας ανοικτών μανδύων από ινοπλέγματα σε ανόργανη μήτρα στην αύξηση της ικανότητας ανάληψης τέμνουσας δύναμης από το στοιχείο. Ειδικότερα, διερευνάται η σχέση του αριθμού των στρώσεων σε μια πιθανή αύξηση καθώς και η τυχόν ευεργετική επίδραση μίας ειδικής τεχνικής για την αγκύρωση των άκρων του μανδύα. Η εξεταζόμενη τεχνική αγκύρωσης αποτελείται από καμπύλα μεταλλικά ελάσματα, μικρού σχετικά πάχους, που τοποθετούνται στα άκρα του μανδύα συγκρατώντας τον, ενώ μηχανικά αγκύρια αναλαμβάνουν να μεταφέρουν τις αναπτυσσόμενες δυνάμεις στη θλιβόμενη ζώνη του στοιχείου, στην πλάκα της δοκού. Από τις πειραματικές δοκιμές εξήχθησαν σημαντικά αποτελέσματα αναφορικά με την αποτελεσματικότητα της μελετηθείσας τεχνικής ενίσχυσης σε τέμνουσα δύναμη πλακοδοκών οπλισμένου σκυροδέματος με χρήση ινοπλεγματών ανόργανης μήτρας (ΙΑΜ), αγκυρωμένων ή μη.
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When strengthening reinforced concrete slabs with textile reinforced mortars (TRM), the “correct” consideration of the global bond behaviour between textile and cementitious matrix is identified as the main challenge in determining the most appropriate global analytical model. The first model evaluated here is based on classical assumptions for structural concrete design. The second model, as another extreme assumption, is completely neglecting textile bond in the cracked zone, thus assuming it as unbonded, end-anchored, external reinforcement. The third model is based on the simplifying assumption of the textile reinforcement being only significantly activated when the internal steel reinforcement is yielding. Analytical results from these approaches are compared to a database containing more than 130 test results reported in literature, and are statistically evaluated.