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Natural fibers are getting a huge interest amongst researchers due to their green, economical and good mechanical properties when employed in different composites as reinforcements. In this work we pre- sent a review on the applications of natural fibers, essentially as composites, for structural purposes with focus on repairing and strengthening of cultural built heritage. Different testing methods with their results combined with the studying of the enhancements attained by applying natural fiber composites, e.g. textile reinforced mortar (TRM), to weak masonry are discussed. Durability challenges mainly due to the hydrophilic nature of the natural fibers are discussed together with some possible solutions., Portuguese foundation for science and technology (FCT) for the PhD scholarship granted to A. Abbass (SFRH/BD/144106/2019)

This paper presents a multi-level experimental and analytical investigation on the mechanical performance of TRM composites used for strengthening existing masonry structures. Micro (fabric-to-mortar bond), meso (TRM-to-substrate bond), and macro (TRM tensile response and in-plane and the out-of-plane ressponse of TRM-strengthened masonry) response of TRMs are combined and investigated in-depth for this reason. These results help to understand the mechanisms controlling the response of these composites and their performance at the structural scale.

This paper presents an optimized washing protocol for as-received natural fibers, prior to large-scale composite manufacturing, for the structural strengthening of historic masonry. The aim was to achieve a simple protocol for standard cleaning of fiber surfaces from low molecular weight constituents that may be detrimental towards interfacial strength without damaging the fibers. The proposed procedure employs the application of the solvent sequence: ethanol, acetone, hexane, with optimized incubation times and stirring conditions. Additionally, this procedure may change the surface of the fiber, thereby enhancing the durability of the fiber-matrix interface. The washing protocol resulted in an increase of tensile strength by 56%, 52% and 22% for flax, hemp and sisal fibers, respectively, as compared to the corresponding non-washed fibers, without loss of elongation. The static contact angle measurements confirmed exposure of a higher fraction of the hydrophilic crystalline cellulose, with a higher wettability observed after washing protocols., This work was partly financed by the Portuguese Foundation for Science and Technology (FCT/MCTES) through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE) under reference UIDB/04029/2020. IPC acknowledges the support of FCT through National Funds References UIDB/05256/2020 and UIDP/05256/2020. The authors wish to acknowledge FCT for the PhD scholarship granted to the first author (SFRH/BD/144106/2019).

Due to the poor shear capacity of unreinforced masonry (URM) walls, it is necessary to strength these elements in the masonry structures. Textile-reinforced mortar (TRM) composites have received extensive attention as a sustainable solution for seismic strengthening of masonry and historical structures. This new system is composed of textile fibers embedded in an inorganic matrix such as lime-based mortar and is applied on the masonry substrate surface as an externally bonded reinforcement (EBR) system. Lime-based mortars are preferred for application to masonry and historical structures due to compatibility, sustainability issues, breathability and capability of accommodating structural movements.

The corner mechanism in masonry structures is one of the out-of-plane modes that may frequently occur under dynamic actions such as earthquakes. The three dimensional motion, in principle complex to treat, can be simplified into a two-dimensional problem, where a prismatic equivalent block is associated to the corner mechanism. This paper provides a method to treat the corner mechanism in two dimensional rocking analysis, taking into account the roof actions especially the roof thrust that acts as destabilizing force in the preliminary phases of motion and the boundary conditions such as the transverse walls. A case study is taken as benchmark to perform rocking non-linear analyses and discuss the role of geometry, energy dissipation and boundary conditions. It is shown the relevant influence of the geometry and of the coefficient of restitution on the stability conditions, whenever the oscillation produce horizontal displacement values of some cm. The results of the case study, subjected to the Central Italy earthquake, are compared to the actual response of the corner mechanism, which collapsed during this seismic swarm, showing that the rocking analysis on the equivalent block correctly predicts the collapse occurred., The Authors thank the Italian Department of Civil Protection and the Consortium RELUIS (2018) for funding this research activity. This work was partially financed by FEDER funds through the Competitiveness Factors Operational Program - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633.

Current Topics and Trends on Durability of Building Materials and Components: Proceedings of the XV edition of the International Conference on Durability of Building Materials and Components (DBMC 2020), Textile-reinforced mortar (TRM) composites have received extensive attention as a sustainable solution for seismic strengthening of masonry and historical structures. This new system is composed of textile fibers embedded in an inorganic matrix and is applied on the masonry and the concrete substrate surface as an externally bonded reinforcement (EBR) system. The bond at the textile-to-mortar interfaces is the main stress-transfer mechanism and, therefore, should be thoroughly investigated. Furthermore, the effectiveness of TRMs in improving the seismic performance of existing structures is highly dependent on the durability of its components, materials, textile-to-mortar bond, and their long-term behavior. Due to the novelty of these materials in application to masonry structures, several aspects related to the durability and long-term performance of them are still not clear. To that end, a new study has been launched that looks at the time effect on the mechanical properties and bond behavior between fiber and mortar. For this purpose, two different hydraulic lime-based mortars, as well as steel and glass fibers, are used to investigate the effect of mortar age on the TRM system after 180 days. The results show that at the early age of mortars, their mechanical properties, and the bond behavior of textile-to-mortar have been increased. Another critical point to remember is that by increasing the mortar age, textile-to-mortar bond and mortar strength are decreased., FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of the project POCI-01-0145-FEDER-007633. The support to the first author through grant SFRH/BD/131282/2017 is acknowledged. Also, the authors would like to thank the Kerakoll Company for supplying the GeoCalce Fino mortar as well as GeoSteel G600 fibers

Application of textile-reinforced mortars (TRMs) for externally bonded reinforcement of existing masonry structures has received a considerable recent attention. The mechanical behaviour of these composites, which are composed of continuous fibers embedded in an organic matrix, and their effectiveness in improving the performance of strengthened structures are highly dependent on the fiber-to-mortar bond behaviour as well as the bond between TRM system and substrate. Understanding the long-term performance of these mechanisms is therefore of critical importance for design of durable TRM composites and ensuring the safety of strengthened structures. To address this aspect, the effect of freeze-thaw cycles on the textile-to-mortar bond behaviour is experimentally investigated and discussed in this paper. The results illustrate a significant deterioration of the textile-to-mortar bond performance in the studied composites., FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER007633. The support to the first author through grant SFRH/BD/131282/2017

Vernacular farmhouses are one of the most notorious and authentic elements of the European rural cultural landscape. For centuries, such structures proved their resilience and adaptability to social and economic changes and are part of rural populations cultural identity. Nonetheless, they are a slowly fading heritage, due to the progressive loss of traditional ways of life and the industrialization of agrarian production methods. Being heritage authenticity and identity features identification a key element to any heritage preservation methodology, this research was set in motion to identify such features regarding Northwest Portuguese farmhouses. The goals were to create a database on vernacular farmhouses context and their role in the construction of the rural landscape, but also to identify representative morphologies and typologies, construction features and durability issues. Taking into consideration the strong loss of authenticity or the severe state of ruin of the majority of most existent examples, the research methodology was based on: i) deep literature review to set the methodologic framework; ii) guided exploratory visits to representative areas of the studied region, to assess in-situ heritage’s main features and state of preservation; iii) selection and analysis of representative case studies of buildings and rural landscapes; iv) assessment and identification of vernacular heritage main design and construction principles; v) guidelines for heritage farmhouses preservation and rehabilitation. Being and ongoing research, the three first steps revelled the existence of a strong regional identity, shaped into two more specific local identities. Agrarian strategies, adaptation to geography and to natural building resources were identified as directly responsible for buildings design, construction principles and specific identity elements. This paper presents the preliminary results of the research and contributes to enlighten researchers to the deep cultural value and importance of preserving this European endangered vernacular heritage., Portuguese Science and Technology Foundation for the scholarships granted (SFRH/BD/ 86704/2012 and SFRH/BD/112646/2015), respectively. This work was partly financed by FEDER funds through the Competitiveness Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633

Lime-based textile-reinforced mortars (TRM) have recently found a growing interest for repair and strengthening of masonry and historical structures. Despite extensive experimental and numerical investigations performed in the last years on the performance of these composites, there is still a lack of fundamental understanding of the fabric-to-mortar bond behaviour (as one of the main mechanisms affecting the cracking and nonlinear response of these composites) and the parameters affecting that. This paper, aimed at addressing this gap, presents a comprehensive experimental and analytical investigation on how the test setup, embedded length, load rate, mortar age and fabric configuration affect the bond behaviour in lime-based TRMs. In total 160 pull-out tests are performed on a glass-based and a steel-based TRM commonly used for strengthening of masonry structures. The results contribute to standardization of the test procedures for characterization of the fabric-to-mortar bond behaviour, to fundamental understanding of this mechanism and to optimization of the design of these composites for enhancing their mechanical response., This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. The support to the first author through grant SFRH/BD/131282/2017 is acknowledged.

Textile reinforced mortars (TRMs) have emerged as a sustainable solution for strengthening existing masonry and concrete structures. As a result, many recent studies have focused on understanding the performance of these composites. However, most of these are aimed at investigating the mechanical properties of TRM composites. At the same time, their durability and long-term performance remain poorly addressed and unclear. This paper presents an experimental study on the effect of freeze–thaw environmental conditions on the micro-mechanical behavior of these composites. The results indicate that the freezing-thawing exposure conditions considered in this study do not have detrimental effects on the mortar strength. However, the fiber-to-mortar bond behavior can deteriorate because the deterioration level depends on the fiber type, embedded length, and fiber configuration.

Historic masonry buildings are characterised by uniqueness, which is intrinsically present in their building techniques, morphological features, architectural decorations, artworks, etc. From the modelling point of view, the degree of detail reached on transforming discrete digital representations of historic buildings, e.g., point clouds, into 3D objects and elements strongly depends on the final purpose of the project. For instance, structural engineers involved in the conservation process of built heritage aim to represent the structural system rigorously, neglecting architectural decorations and other details. Following this principle, the software industry is focusing on the definition of a parametric modelling approach, which allows performing the transition from half-raw survey data (point clouds) to geometrical entities in nearly no time. In this paper, a novel parametric Scan-to-FEM approach suitable for architectural heritage is presented. The proposed strategy uses the Generative Programming paradigm implementing a modelling framework into a visual programming environment. Such an approach starts from the 3D survey of the case-study structure and culminates with the definition of a detailed finite element model that can be exploited to predict future scenarios. This approach is appropriate for architectural heritage characterised by symmetries, repetition of modules and architectural orders, making the Scan-to-FEM transition fast and efficient. A Portuguese monument is adopted as a pilot case to validate the proposed procedure. In order to obtain a proper digital twin of this structure, the generated parametric model is imported into an FE environment and then calibrated via an inverse dynamic problem, using as reference metrics the modal properties identified from field acceleration data recorded before and after a retrofitting intervention. After assessing the effectiveness of the strengthening measures, the digital twin ability of reproducing past and future damage scenarios of the church is validated through nonlinear static analyses., This work was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. This research was partially carried out within the framework of the National Operational Programme on Research and Innovation (Attraction and International Mobility) PON-AIM 2014-2020 Line 2, co-financed by the European Social Fund and by the National Rotation Fund.

Reliable design and application of textile-reinforced mortar (TRM) composites for the repair of existing masonry and concrete structures requires a fundamental understanding of the textile-to-mortar bond behavior as one of the main mechanisms controlling their nonlinear response and cracking behavior. Suitable test setups and analytical models are needed to extract the bond-slip laws from the experimental pull-out tests. This paper proposes a new bond-slip law and analytical model, which predicts the bond behavior of lime and cement-based TRM composites considering the slip hardening and softening effects observed in experimental tests. For this purpose, the pull-out response of experimental specimens with different fiber types (steel and glass), bond lengths, and mortar age are analyzed, and their bond slip-laws are extracted. The accuracy of the developed model is shown by comparing analytical and experimental results.

In this work a multidisciplinary approach for the structural assessment of masonry arch bridges is presented. The Vilanova Bridge, located in Galicia, northwest of Spain, is considered for the implementation of the methodology. A comprehensive field survey fully based on non-destructive testing techniques, which integrates laser scanning, ground penetration radar, sonic tests and ambient vibration testing, is proposed. It provides all the necessary geometric data to build an accurate and detailed three-dimensional finite element model. The calibration of the model is then carried out through the coupling with an optimization algorithm, which minimizes the discrepancies with respect to the experimentally obtained modal properties. The structural analysis of the bridge is addressed in the last stage. A sensitivity analysis involving different loading scenarios and the plausible variation of the masonry and soil material properties is performed. The results demonstrate the significant influence of tensile non-linear properties of masonry, but also the key role played by fill materials on the arch bridge performance. Lastly, the advantages of adopting a three-dimensional modelling approach are also pointed out, since the apparition of critical transverse effects in the response of the structure is successfully captured by the developed numerical model., This work has been partially supported by the Spanish Ministry of Economy and Competitiveness through the project "HERMES-S3D: Healthy and Efficient Routes in Massive Open-Data based Smart Cities (Ref.: TIN2013-46801-C4-4-R), and by FEDER funds through the Competitiveness Factors Operational Programme - COMPETE and by national funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633., info:eu-repo/semantics/publishedVersion

Key Engineering Materials, vol. 747., An experimental and numerical investigation on an innovative composite reinforced with sisal fibers for masonry strengthening is presented in this paper. A FEM numerical approach is also developed, based on diagonal compression test results, to simulate the shear in-plane response of unreinforced masonry panels (URM) and masonry strengthened with a Fibre Reinforced Cementitious Matrix (FRCM) composite system made with sisal fibers (RM-SISAL)., The authors acknowledge the support of the research project PRIN 2015 (under grant 2015JW9NJT_014, project “Advanced mechanical modeling of new materials and structures for the solution of 2020 Horizon challenges”) and Fibre Net Srl (Pavia di Udine, Italy) for the support given in the experimental tests. This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of projects POCI-01-0145-FEDER007633., info:eu-repo/semantics/publishedVersion

The numerical analysis of masonry arch bridges requires detailed information about the geometry and mechanical properties of all the bridge components. As for the geometry, masonry bridges present complex shapes, being the characterization of the inner geometry (e.g. arch thickness or presence of backing) still a relevant challenge. As for mechanical properties, which are hardly measurable, they are essential for a reliable definition of the load carrying capacity. This paper presents a multidisciplinary approach based on the use of non-destructive testing techniques and describes critically its application to a medieval masonry arch bridge. The geometric characterization is based on a detailed laser scanning and ground penetrating radar survey, allowing determining the external and inner geometry of the bridge. Regarding material properties, indirect sonic tests were conducted on piers and spandrels to obtain the dynamic elastic modulus of stones. In addition, a dynamic identification test was carried out to characterize the dynamic properties of the bridge., (undefined)

Results of an experimental campaign conducted on plain and reinforced masonry wallettes subjected to diagonal compression tests are presented in this paper. The masonry panels were reinforced by means of two strengthening techniques: structural repointing achieved by inserting basalt bars in the mortar bed joints and fiber reinforced cementitious matrix (FRCM) composite, obtained by applying a single-ply glass mesh on the sides of the specimens. The structural effects of symmetric and asymmetric strengthening configurations are investigated. The main mechanical parameters, such as shear capacity, ductility and shear modulus, are compared and discussed introducing a calibrated reinforcement ratio. Further, analytical procedures presented in the codes and in literature are followed to predict the shear capacity of the unstrengthened and strengthened wallettes and, finally, compared to the values obtained experimentally., This work was partly financed by FEDER funds through the Operational Programme Competitiveness Factors (COMPETE) and by national funds through the Foundation for Science and Technology (project POCI-01-0145-FEDER-007633). The collaboration of Mr. Mattia Girolomini and the support of the technical staff from the Structural Laboratory of University of Minho during the experimental campaign are gratefully acknowledged. Authors are also grateful to MagmaTech Ltd for kindly providing the basalt bars.

A significant number of old unreinforced load-bearing masonry (URM) buildings exist in many countries worldwide, but especially in Europe. In particular, Bosnia and Herzegovina has an important stock of masonry buildings constructed from the 1920s until the 1960s without application of any seismic code, due to their nonexistence at that time. With the 1963 Skopje earthquake, this class of buildings were shown to be rather vulnerable to seismic actions, which exhibited serious damage. This article assesses the seismic vulnerability of a typical multi-storey residential unreinforced load-bearing masonry building located in the heart of Sarajevo, which may be exposed to an earthquake of magnitude up to 6 by Richter’s scale. The buildings of this kind make up to 6% of the entire housing stock in the urban region of Sarajevo, while in Slovenia this percentage is much higher (around 30%). The analysis of a typical building located in Sarajevo revealed its drawbacks and the need for some kind of strengthening intervention to be implemented. Additionally, many structures of this type are overstressed by one to two additional floors (not the case of the analyzed structure) constructed from 1996 onwards. This was due to the massive population increase in the city center of Sarajevo and further increased the vulnerability of these buildings., info:eu-repo/semantics/publishedVersion

[Excerpt] 17.1 Introduction Fiber-reinforced polymers (FRPs) have been extensively used for seismic strengthening of existing concrete and masonry structures. The ease of application and high strength-to-weight ratio of these composites have made them an interesting solution for strengthening purposes.[...], (undefined)

The strengthening of masonry structures using composite-based solutions has received significant research attention in recent years due to their proved considerable influence on enhancing structural characteristics, for example, stiffness and strength. In spite of the all achieved advances, numerous drawbacks have been noticed, in particular when conventional fiber-reinforced polymers are used. Thus novel techniques such as textile-reinforced mortar (TRM) have been introduced to overcome these issues. This chapter addresses key aspects of nonlinear finite element modeling of TRM composites. It mainly discusses the macromodeling approach as it requires fewer details (material characteristics) and less computational effort with respect to the micromodeling strategy, making it possible to use this approach in complex practical projects. Experimentally observed behaviors and characterization of required material properties are considered and knowledge gaps are highlighted. Finally, a series of numerical macromodeling applications on masonry structures are discussed, involving different construction materials. Pushover analyses are conducted to assess the influence of TRMs on both in-plane and out-of-plane seismic responses, (undefined)

Raw earth is among the most ancient building materials and the related building techniques are found widespread around the world. Currently, it is estimated that about 25% of the global population lives in earthen buildings and about 10% of the UNESCO World Heritage is built with earth. Nevertheless, an important overlap can be observed when the geographical distribution of raw earth constructions is compared with that of the seismic hazard. This circumstance, combined with the seismic vulnerability of earthen buildings, results in a high seismic risk, as demonstrated by recent moderate earthquakes. Despite the current awareness for this problem, little has been done so far to develop proper strengthening solutions for the rammed earth heritage. Based on the effectiveness of externally bonded fibers for masonry buildings, the strengthening of rammed earth walls with an earth mortar coating reinforced with a geomesh is here adopted as a compatible solution. The objective of this work is to investigate and characterize the bond behavior of the above mentioned strengthening solution to further describe the response of the interaction mortar-mesh. To this purpose, an experimental program was undertaken based on a series of pull-out tests. Specimens were prepared using earth mortar, two different types of meshes (glass fiber and nylon) and considering different bonded lengths. The results highlighted distinct bond behaviors. In the case of the glass fiber mesh, the bond was granted by friction and mechanical interlocking, while the mechanical anchorage promoted by the transversal yarns granted the bond of the nylon mesh., FCT - Fuel Cell Technologies Program(SafEarth - PTDC/ ECM-EST/2777/2014), This work was partly financed by FEDER funds through the Operational Programme Competitiveness Factors (COMPETE 2020) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project SafEarth - PTDC/ ECM-EST/2777/2014 (POCI-01-0145-FEDER-016737). The support from grants SFRH/BD/ 131006/2017 and SFRH/BPD/97082/2013 is also acknowledged

Application of Fibre Reinforced Polymers (FRPs) as external reinforcement for masonry structures has been found to be a promising technique, but the long-term behavior of such systems still needs attention. This study presents an overview of the experimental activities followed by the authors on durability of externally bonded FRP-masonry components subjected to water immersion and accelerated hygrothermal exposure. Both moist and hygrothermal environments were found to be extremely deteriorating in the studied materials and led to significant degradation of mechanical properties and loss in bond strength. The effect of mechanical surface treatment on the bond durability performance was also investigated., This work was supported by the Competitivity Factor Operational Program (COMPETE) and the Foundation for Science and Technology (FCT) within the scope of the project POCI-01-0145-FEDER-007633. The first author would like to acknowledge the financial support of the Ministerio da Ciencia, Tecnologia e Ensino Superior, FCT, Portugal, under the grant SFRH/BD/117114/2016.

The use of Textile Reinforced Mortar (TRM) composites for Externally Bonded Reinforcement (EBR) of reinforced concrete (RC) and masonry structures has attracted several attentions during the last years. The effectiveness of these composites in structural reinforcement is significantly dependent on the TRM-to-substrate and the fiber-to-mortar bond behavior. Despite the importance of the latter, that controls the crack distribution on these composites, have received few attentions and is relatively unknown.This paper presents a combined experimental and analytical study on the effect of fiber-embedded length and configuration on the pull-out response. From the obtained results, bond-slip laws are proposed for TRM composites made of unidirectional and bidirectional grids. The tests are performed on a (unidirectional) steel-based and a (bidirectional) glass-based TRM composite as common reinforcing systems. A comparison is also made between the results obtained from single-fiber pull-out tests and conventional single-lap shear bond tests to highlight the differences/similarities between these two test methods., This work was partly financed by FEDER funds through the Competitively Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. The support to the first author through grant SFRH/BD/131282/2017 is acknowledged. The second author acknowledges the financial support of the European Union's Marie Curie Individual Fellowship program under REA grant agreement No. 701531. In addition, authors would like to thank the Kerakoll Company for supplying the GeoCalce Fino mortar as well as GeoSteel G600 fibers., info:eu-repo/semantics/publishedVersion

Textile-reinforced mortar (TRM) composites, composed of textile fibers embedded in an inorganic matrix, have been found to be a sustainable solution for strengthening of existing masonry and concrete structures. Despite the extensive recent attention in understanding the mechanical performance of these composite, their long-term performance and durability remain basically unknown. To address this gap, this paper presents a comprehensive experimental and analytical study on the changes in the mechanical response of these composites across scales (from material characterization to bond and tensile tests of TRM composites) under indoor and outdoor conditions. For this purpose, steel and glass fibers with lime-based mortar are used to investigate the pull-out response and the tensile behavior of TRM composites. The results show that the long-term behavior of TRM composites for different ages is significantly dependent on the mortar and fiber combination and, therefore, can change notably between different TRM solutions. It is also observed that lime-based TRMs cannot reach their full mechanical properties under indoor conditions even after 3 years. Outdoor conditions lead to better curing of the samples and achieving significantly higher mechanical properties in these composites. However, it can also lead to a significant deterioration at later ages., This work was partly financed by FEDER funds through the Competitivity Factors Operational Program (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of the project POCI-01-0145-FEDER-007633. The support to the first author through grant SFRH/BD/131282/2017 is acknowledged. Besides, the authors would like to thank the Kerakoll Company for supplying the GeoCalce Fino mortar as well as GeoSteel G600 fibers.

Externally bonded strengthening of masonry structures using Fiber Reinforced Polymers (FRPs) has been accepted as a promising technique. Although the effectiveness of FRPs in improving the performance of masonry components has been extensively investigated, their long-term performance and durability remain poorly addressed. This paper, tackling one of the aspects related to durability of these systems, presents an experimental investigation on the effect of long-term (one year) water immersion on the performance of GFRP-strengthened bricks. The tests include materials' mechanical tests, as well as pull-off and single-lap shear bond tests, to investigate the changes in material properties and bond behavior with immersion time, respectively. The effect of mechanical surface treatment on the durability of the strengthened system as well as the reversibility of the degradation upon partial drying are also investigated. The experimental results are presented and critically discussed., The second author acknowledges the financial support of the Ministerio da Ciencia, Tecnologia e Ensino Superior, FCT, Portugal, under the grant SFRH/BPD/92614/2013.

Knowing and understanding historical building materials and techniques is a fundamental step to ensure successful heritage preservation procedures. An experimental campaign was designed and implemented to acquire scientific information about the physical and mechanical behaviour of schists and granites used in Northwest Portuguese vernacular dry stone masonry. Results show schists strong anisotropy, and influence of foliation regularity, over the main physical and mechanical parameters. Granites isotropy and compact and heterogeneous fabric result in higher strength and lower water absorptions. Moreover, results show the negative effects of water over stones strength and elastic parameters., This work was partially financed by FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT), Portugal, within the scope of project POCI-01-0145-FEDER007633. Authors wish to express their gratitude to the Municipality of Arcos de Valdevez and the Barqueiros civil parish, and to the company Artecanter for its support with the specimens’ preparation. The first author expresses his gratitude to the Foundation for Science and Technology (FCT), Portugal, for the scholarships granted (SFRH/BD/ 86704/2012).

Textile-reinforced mortars (TRM) have recently received significant attention for the externally bonded reinforcement (EBR) of masonry and reinforced concrete structures. The fiber-to-mortar bond, the TRM-to-substrate bond, and the mechanical properties of the TRM constituents have a fundamental role in the performance of this strengthening technique and therefore require special attention. Despite this importance, only few investigations are devoted to characterization of the single fiber-to-mortar bond response in these systems.This paper, as an step towards addressing the fiber-to-mortar bond, presents a combined experimental and analytical investigation on the effect of test setup on the pull-out response and bond-slip laws in TRM composites. Three different pull-out test setups, consisting of one pull-pull and two pull-push configurations, are developed and investigated for characterization of the single fiber-to-mortar bond behavior. The experimental and analytical results are critically discussed and presented and bond-slip laws are extracted for each test setup., This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. The support to the first author through grant SFRH/BD/131282/2017 is acknowledged. The second author acknowledges the financial support of the European Union's Marie Curie Individual Fellowship program under REA grant agreement No. 701531., info:eu-repo/semantics/publishedVersion

To make the territory more usable for farming, rural populations used and perfected masonry walls for centuries to help organize the landscape, to establish boundaries between different landowners and to protect crops and property from animals and other external threats. In recent decades, the rural territory of Northwest Portugal undertook an irreversible transformation from a purely rural into a low-density urban land. In this process, traditional farm walls were faced with contemporary needs and population demands, which in most cases ended with demolition of the walls and their replacement by new ones. In this context, the landscape heritage value and rural identity preservation depend to a large extent on the rebuilding solutions chosen to replace the demolished wall heritage.This paper addresses the analysis of traditional schist farm walls from Northwest Portugal. The study starts by focusing on their authenticity and by identifying characteristic features, as well as analysing the existing wall typologies, morphologies and main constructive features. The schist stone used for centuries as a building raw material is characterized from the physical and mechanical points of view. A rebuilding methodology was then applied to a case study, for which different local contemporary rebuilding solutions were identified and characterized. A decision-making process was established according to specific intervention guidelines, with implementation of the chosen solution presented in detail.Finally, this paper aims also to enlighten researchers, technicians and builders to the importance and need of protecting the endangered vernacular masonry walls' heritage, and to contribute to the development of suitable rehabilitation and rebuilding solutions for similar types of interventions., This work was partially financed by FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI-01-0145-FEDER-007633. Authors wish to express their gratitude to the Barqueiros parish council and to the companies Construjouve, for their support during the construction of the wall, and Artecanter for their support with the specimens' preparation. The first author expresses his gratitude to the Portuguese Science and Technology Foundation for the scholarships granted (SFRH/BD/86704/2012)., info:eu-repo/semantics/publishedVersion

This article presents a novel segmentation algorithm that allows the automatic segmentation of masonry blocks from a 3D point cloud acquired with LiDAR technology, for both stationary and mobile devices. The point cloud segmentation algorithm is based on a 2.5D approach that creates images based on the intensity attribute of LiDAR systems. Image processing algorithms based on an improvement of the marked-controlled watershed was successfully used to produce the automatic segmentation of the point cloud in the 3D space isolating each individual stone block. Finally, morphologic analysis in two case studies has been carried out. The morphologic analysis provides information about the assemblage of masonry pieces, which is valuable for the structural evaluation of masonry buildings.

Fibre-reinforced composite materials have gained an increasing success, mostly for strengthening, retrofitting, and repairing existing structures. However some problems may arise with the use of traditional FRP (Fiber Reinforced Polymer), particularly when the compatibility with the substrate and the reversibility of the intervention are required, as in case of cultural heritage buildings, or specific exposition conditions may compromise the long term effectiveness of the reinforcement, as in presence of high temperature and humidity. Starting from these considerations new composite materials are emerging as a more effective solution in certain fields of application and under specific service conditions; in this context, mortar-based composite systems, consisting of one or more layers of uni- or bi-directional fibre nets embedded in cement/lime-based matrix layers, can be used as reinforcement of both concrete and masonry structures. However, the research work dealing with these emerging materials and their performances when used as a strengthening system for existing structures is still limited. Both experimental and theoretical investigations are needed in order to deliver reliable design methodologies. In this work, a Round Robin Test aimed to the characterization of both bond with the existing substrate and tensile performance of glass fabric (in the form of grids) coupled with inorganic mortar matrices is presented. The investigation was conducted at fifteen laboratories involved in the RILEM Technical Committee 250-CSM (Composites for the Sustainable Strengthening of Masonry). With the aim of studying the bond behaviour between Fabric Reinforced Cementitious Matrix (FRCM) composites and masonry substrate, single and double lap shear tests were carried out on brick-masonry prisms. Results provide useful informations about the mechanical properties, the bond capacity and the failure mechanisms of different commercially available glass FRCM systems. Finally, critical aspects are underlined to address the progress of research work., info:eu-repo/semantics/publishedVersion

The compatible strengthening of historical constructions is a critical issue in modern restoration practice. Among others, numerical modelling became a powerful instrument in the practice of checking the suitability and effectiveness of a given structural strengthening solution. In particular, the topic of numerical modelling of masonry arches and vaults was developed by many researchers for several years. This paper is focused on the numerical representation of a traditional strengthening technique, based on the use of transversal masonry diaphragms applied to arches and vaults. Macro and micromodelling approaches were considered in this work as to discuss the adequacy and efficiency of the strengthened method and also compare results between the two approaches. To further define the properties and effectiveness of the strengthening solution, a parametric study was conducted by means of geometrical and mechanical modifications applied to the diaphragms.

The paper presents a comparison between different numerical modelling approaches aiming to simulate the in-plain behaviour of three types of earthen materials, namely adobe masonry, rammed earth and cob. For this purpose, uniaxial and diagonal compression tests were carried out, which allowed determining important mechanical parameters, such as compressive strength, Young's modulus, Poisson's ratio, shear strength and shear modulus. Furthermore, the tests allowed assessing the level of non-linear behaviour of the respective stress-strain relationships as well as the failure modes. The experimental results were then used for the calibration of numerical models (based on the finite element method) for simulating the non-linear behaviour of the earth materials under in-plane shear loading. Both macro- and micro-modelling approaches were considered for this purpose. The procedures adopted for model calibration established the reliability of various modelling strategies for the different loading conditions. The simplified approach based on macro-modelling shows a satisfactory accuracy and low computational costs. The results reproducing the uniaxial compression are in good correspondence with the post-elastic behaviour observed in the experimental campaign. The micro-modelling approach adopted to reproduce the shear behaviour, even with higher computational cost, represents a suitable tool to predict the adobe masonry and rammed earth collapse mechanisms., This study was partially funded by European Commission within the framework of the project NIKER (grant number 244123) dealing with improving immovable Cultural Heritage assets against the risk of earthquakes. The study was also partly financed by FEDER funds through the Competitivity Factors Operational Programme (project POCI-01-0145-FEDER007633) and by national funds through Portuguese Foundation for Science and Technology (project PTDC/ECM-EST/2777/2014 and grant SFRH/BPD/97082/2013). The authors wish to acknowledge Mr. André Gardei and Mr. Jürgen Kuhn for their support in samples preparation and tests setup., info:eu-repo/semantics/publishedVersion

Textile Reinforced Mortars (TRMs) have found extensive attention for externally bonded reinforcement of masonry and historical structures. However, only few information is available regarding their mechanical properties and effectiveness in improving the seismic performance of strengthened structures. This paper presents an extensive numerical investigation on the effect of TRM composites on the nonlinear response and failure modes of masonry walls. The effect of boundary conditions and the TRM type on the performance of strengthened walls are critically discussed and presented. It is shown that the performance and failure mode of the walls can significantly change after strengthening, an important issue that should be considered at the design stage. Finally, the effect of TRM application on the nonlinear response of a large historical masonry facade in Macau is investigated and presented., The first author is grateful to the SAHC Master Programme for the grant awarded. The second author acknowledges the financial support of the Ministerio da Ciencia, Tecnologia e Ensino Superior, FCT, Portugal, under the grant SFRH/BPD/92614/2013 as well as the financial support of the European Union's Marie Curie Individual Fellowship program under REA grant agreement No. 701531., info:eu-repo/semantics/publishedVersion

Key Engineering Materials, vol. 747., Tensile Reinforced Mortars (TRMs) are promising composites that address the compatibility demands required for strengthening of masonry and historical constructions. Although many recent studies have been devoted to the use of these materials for strengthening purposes, several issues such as efficiency for improving the structural performance are clearly open. The aim of this paper is to numerically investigate the effectiveness of TRM systems on the in-plane and out-of-plane response of masonry walls. Numerical models are adopted to describe the nonlinear behaviour and the failure mechanisms of unreinforced and strengthened walls. It is shown that the implementation of TRM layers improve largely the performance of the masonry walls both in terms of strength and displacement capacity., (undefined), info:eu-repo/semantics/publishedVersion

The demand for building materials and techniques with reduced environmental impact has been increasing in the last few years. Thus, efforts have been taken to include alternative raw materials with reduced extraction impacts and low embodied energy in their production, namely natural materials and industrial by-products with low or no processing needs. Nevertheless, the lack of technical knowledge about this type of materials leads to issues related with its safety, quality and durability. The work presented in this paper intends to be a contribution on this topic. Thus, an experimental program was carried out to evaluate the mechanical performance of interlocking compressed earth blocks (ICEBs) stabilised with activated alkali fly ash. The main objective of the experimental program was to assess the possibility of further exploiting the mechanical performance of the original dry-stack masonry system, by means of the use of mortared joints. Two alkali-activated binder based earth mortars were used for this purpose, and the results showed that a substantial mechanical improvement is obtained in terms of compression and shear behaviour of the respective masonry., This work is financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by Portuguese funds through FCT - Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633. The support from grant SFRH/BPD/97082/2013 is also acknowledged. The authors wish to express their gratitude to Eng. Jorge Henriques, on behalf of the company PEGOP - Energia Electrica SA, for providing the fly ash, and to Eng. Miguel Rodrigues, on behalf of the company CJR GROUP, for providing the soil.

The acoustic emission (AE) technique is used for investigating the interfacial fracture and damage propagation in GFRP- and SRG-strengthened bricks during debonding tests. The bond behavior is investigated through single-lap shear bond tests and the fracture progress during the tests is recorded by means of AE sensors. The effect of hygrothermal conditions on the debonding characteristics and failure mode is also investigated by performing accelerated ageing tests. Accelerated ageing tests resulted in a change of failure mode in GFRP-strengthened specimens which helped in assessment of AE output in different failure modes, but no conclusive strength degradation was observed in the specimens. The results show that the average and cumulative AE energy are correlated to the FRP slip and debonding fracture energy in GFRPstrengthened specimens, respectively. The fracture progress and active debonding mechanisms are characterized using results from the AE technique. Moreover, a clear distinction between the AE outputs of specimens with different failure modes, in both SRG- and GFRP-strengthened specimens, is found which allows characterizing the debonding failure mode based on acoustic emission data. The tests performed in this study are also a contribution towards the application of AE techniques for on-site health monitoring of strengthened masonry structures., Fundação para a Ciência e Tecnologia

Nowadays, there is an increasing interest in using fibre reinforced polymers (FRP) for strengthening masonry elements. It has been observed that these materials, when used for externally bonded reinforcement (EBR), improve the performance of masonry components. However, issues such as durability and longterm performance of strengthened elements are still open. The bond between composite material and masonry substrate is a critical mechanism in EBR strengthening techniques, and therefore its durability and long-term performance should be deeply investigated and characterized. In the present study, the influence of hygrothermal conditions (combined effect of moisture and temperature) on the bond performance is investigated by performing single-lap shear bond tests on two sets of GFRP-strengthened specimens. Different surface preparation techniques are used for each set of specimens to study their effects on the bond degradation. The effect of boundary conditions on FRP delamination is also investigated through visual inspection. The results showed surface grinding significantly improves the bond durability. Extreme FRP delamination was observed in specimens prepared with original brick’s surfaces, being mainly due to thermal incompatibility., (undefined)

The absence of appropriate structural connections is known to be one of the main factors contributing to the activation of out-of-plane mechanisms of masonry walls that can compromise the entire stability of a building. The high vulnerability of historical unreinforced masonry buildings to these types of mechanisms imposes the necessity to develop engineered strengthening solutions capable of ensuring positivewall-diaphragm anchorage to work in tension.A design methodology was developed covering aspects related to the estimation of the seismic demand and the design of a retrofit solution studied experimentally. The procedure proposed relies on the assessment of the resistant capacity associated with several possible failure modes and the estimation of the seismic demand considering the existing recommendations found on Eurocode 8 (CEN/TC 250 2010), ASCE/SEI 41-13, and NZSEE (2006)., The authors would like to acknowledge Professor Jason Ingham for providing essential information and technical expertise concerning the NZSEE (2006) application. This work was partially funded by project FP7-ENV-2009-1-244123-NIKER of the 7th Framework Program of the European Commission, and by FCT, within ISISE, project UID/ECI/04029/2013, which are gratefully acknowledged.

Full characterization of the bond behavior between Fiber Reinforced Polymers (FRPs) and masonry in externally bonded reinforcement (EBR) technique is crucial at the design stage or structural performance prediction. In this regard, a full-field assessment technique seems to be valuable for an adequate characterization of the bond behavior. The digital image correlation (DIC) and feature tracking techniques have been used in this study for investigating the evolution of strains and deformation during uniaxial tensile tests and shear debonding tests in FRP-masonry systems. The results show that the DIC is a valuable technique for characterization of the bond behavior and investigating its three-dimensional aspects. The DIC was also found applicable for following the matrix crack development in Steel Reinforced Grout (SRG) specimens. Feature tracking method was used for monitoring the strains development on the steel fibers in SRG specimens during tensile tests.

Fiber reinforced polymers are being extensively used for external strengthening of masonry structures. However, durability of this strengthening technique under environmental conditions is still under inves- tigation. Previous studies indicate that moisture plays an important role in the durability of bond between FRP and substrate. Moisture can cause degradation in the bond behavior and also in the mechan- ical properties of the constituent materials. This paper presents and discusses the results of an experi- mental investigation on the effects of moisture on the bond behavior in FRP-strengthened masonry bricks. The degradation in the bond performance has been investigated by performing pull-off and pull-out tests on the conditioned specimens. The change in the mechanical properties of the materials has also been investigated. Comparative analysis has been performed and the results are presented and critically discussed., This work was partly funded by project FP7-ENV-2009-1-244123-NIKER of the 7th Framework Program of the European Commission, which is gratefully acknowledged. The first author also acknowledges the financial support of the Portuguese Science Foundation (Fundacao de Ciencia e Tecnologia, FCT), through grant SFRH/BD/80697/2011.

Contemporary world is facing numerous bomb explosion attacks on public and civil buildings causing huge loss of property and human lives. As a consequence, the society needs more safety and protection for the existing structures against blast loads. Among the various strategies, one effective way to enhance the blast resistance of reinforced concrete and masonry structures is through retrofitting using various types and forms of fibrous and composite materials. This work presents an up to date review of available literature and publications on the fibrous and composite materials utilized for blast protection of structural elements and highlights the lacking areas where further research is required.

The paper discusses the behavior of a typical masonry building in Bosnia and Herzegovina built in the 1950s without any seismic guidelines. A global numerical model of the building has been built and masonry material has been simulated as nonlinear. Additionally, calculations done with a “less” sophisticated model are in a good correlation with the finite element method (FEM) calculations. It was able to “grasp” the damage pattern; not as detailed as in the FEM calculations, but still quite good. On the basis of this it may be concluded that in this case calculation with Frame by Macro Elements (FME) program could be recommended for future analysis of this type of structures, having quite good results with a less computation time. However, in the need for more precise results FEM should be utilized.

Publicado em "Brick and block masonry : trends, innovations and challenges : proceedings of the 16th International Brick and Block Masonry Conference (IBMAC 2016)...", ISBN 978-1-138-02999-6, Although earthen construction has been practiced for millennia, its advantages associated to current environmental concerns are giving new opportunities to earth as a modern building material. The paper presents and discusses the first results of an experimental campaign carried out at University of Minho on the characterization of masonry components made of stabilized compressed earth blocks, produced with granitic residual soils, typically from Northern Portugal, and considering both dry-stack and mortared joints. The use of mortar joints modifies significantly the mechanical behaviour of masonry, both in terms of stiffness and strength., FCT, within ISISE, project UID/ECI/04029/2013, Fundação para a Ciência e Tecnologia (FCT) - SFRH/BPD/97082/2013

Proper structural connections play an important role in ensuring seismic loads distribution and developing global damage mechanisms of structures. In historical unreinforced masonry buildings, effective connections between masonry walls and timber floors or walls through the use of anchors can prevent the occurrence of out-of-plane mechanisms and promote box-like behavior. Particularly for historic structures, injection anchors can comply with requirements as decreased architectural impact and minimum intervention. Therefore, this paper aims at developing structural design parameters and recommendations that allow the design of connections retrofitted with injection anchors, found in historical unreinforced masonry buildings, built during the 19th century, in Portugal. Existing strength prediction formulae based on behavior models, and idealized force-displacement curves were developed to better fit the results obtained from a series of quasi-static monotonic and cyclic pullout tests carried out on pairs of injection anchors. Behavior models were able to approximate the experimental results, if adapted to the specificities of historical masonry. Further validation is needed, particularly for the combined cone-bond model. From the idealized curves, displacement acceptance criteria, expected forces, and behavior factors were proposed, according to the performance-based approaches recommended by EC8-Part 3 and ASCE/SEI 41-13. Finally, retrofit design recommendations were addressed., This work was partially funded by project FP7-ENV-2009-1-244123-NIKER of the 7th Framework Program of the European Commission, which is gratefully acknowledged. Authors would like to thank the technical staff of the Structures Lab. of University of Minho for the assistance provided preparing and carrying out the tests and also, Monumenta, Ltd. for the construction of the specimens and Cintec® for the installation of the injection anchors.

Externally bonded reinforcement (EBR) of masonry structures with Fiber Reinforced Polymers (FRPs) has received extensive attention during the last years. Despite the vast literature on mechanics and short-term performance, the durability and long-term performance of these systems still remain insufficiently studied. Structures are subjected to harsh environments such as coupled temperature and moisture variations (hygrothermal conditions) during their service life. A clear understanding on the performance of the strengthening system under these conditions is critical at the design stage.This paper presents an experimental investigation on the effect of long-term hygrothermal conditions on FRP-strengthened masonry components. The focus is on the interfacial bond behavior and materials mechanical properties. The effect of mechanical surface treatment on the bond durability is also investigated., The second author acknowledges the financial support of the Ministerio da Ciencia, Tecnologia e Ensino Superior, FCT, Portugal, under the grant SFRH/BPD/92614/2013., info:eu-repo/semantics/publishedVersion

The paper presents an experimental investigation on an innovative repair method, in which composite reinforcements, after debonding, are re-bonded to the substrate using a highly deformable polymer. In order to assess the effectiveness of this solution, shear bond tests were carried out on brick and masonry substrates within two Round Robin Test series organized by the RILEM TC 250-CSM: Composites for the Sustainable strengthening of Masonry. Five laboratories from Italy, Poland and Portugal were involved. The shear bond performance of the reinforcement systems before and after repair were compared in terms of ultimate loads, load–displacement curves and strain distributions. The results showed that the proposed repair method may provide higher strength and ductility than stiff epoxy resins, making it an effective and cost efficient technique for several perspective structural applications.

Innovative composite materials made of continuous fibers embedded in mortar matrices have been recently received attention for externally bonded reinforcement of masonry structures. In this regards, application of natural fibers for strengthening of the repair mortars is attractive due to their low specific weight, sustainability and recyclability. This paper presents experimental characterization of tensile and pull-out behavior of natural fibers embedded in two different mortar-based matrices. A lime-based and a geopolymeric-based mortar are used as sustainable and innovative matrices. The obtained experimental results and observations are presented and discussed.

Stone masonrywalls are the most relevant structural element in the seismic response of a masonry building. Once the out-of-plane mechanism are adequately prevented, the seismic response of a building depends on the in-plane strength capacity of its walls. This paper presents a discussion on the in-plane behaviour of masonry panels with different slenderness ratios and distinct levels of compression load, subjected to shear loading, using advanced numerical simulations. The numerical study is based on an experimental campaign performed at the University of Pavia on stone masonry piers. The calibrated models were also used to carry out parametric analysis varying the geometric wall configuration and the pre-compression level. Distinct walls subjected to different stress levelswere assessed and the influence of these parameters on the in-plane behaviour is discussed., The second author would like to express her gratitude to the National Foundation for Science and Technology (FCT) for the PhD grant SFRH/BD/71599/2010. This work was supported by FCT, within ISISE, project UID/ECI/04029/2013.