166 research outputs found
FRP strengthening of masonry arches: analysis of local mechanisms and global behaviour
No full textIn the last two decades, FRP (Fibre-Reinforced Polymers) composite materials have been adopted for strengthening and repair of both modern and historic masonry constructions (buildings, bridges, towers) and structural components (walls, arches and vaults, piers and columns).
Strengthening of masonry brick arches and vaults with FRP laminates can contribute significantly in the improvement of their structural capacity at a limit state, by activating local mechanisms both at material and interface levels, but also modifies the collapse mechanisms of the original structures, as the reinforcement prevents the typical brittle failure due to the formation of hinge-mechanisms.
Despite the increasing number of specific studies on FRP reinforcement of masonry structures, investigations are still limited if compared to reinforced concrete applications. Moreover, few codes and recommendations are currently available.
Starting from these points, the present work deals with experimental investigations on three local mechanisms involved by the collapse of FRP-reinforced masonry arches: the interface behaviour in the case of stresses normal to the surface (FRP detachment observed in structures with intrados reinforcement) has been investigated through the execution of a large number of combined tests on solid clay bricks (flexural, compressive, splitting and pull-off tests) aimed at experimentally calibrate possible correlations among the corresponding strength parameters and to observed possible influences of the fibres type and the presence of primer on the pull-off behaviour; the bond behaviour has been investigated by performing ten Double-lap Shear Tests on solid clay bricks, aimed at calibrating fracture energy value and bond-slip law for both carbon FRP and glass FRP reinforcement (moreover, a simple exponential-based bond-slip law has been proposed); the mixed-mode behaviour (fourteen tested samples) has been investigated by adapting a test setup developed for FRP applications on reinforced concrete, known as V-shape Peel Test, to clay substrate, in order to reproduce on a local scale the conditions related to the shear sliding failure of arches with extrados reinforcement.
Finally, several case studies, concerning real-scale or scaled brick masonry arches and vaults reinforced at their intrados or extrados, have been collected from literature in order to compare the experimental results to the available interpretative models of the global behaviour of the structure at failure.Negli ultimi due decenni, i materiali compositi FRP (Fibre-Reinforced Polymers) sono stati adottati anche nel rinforzo di costruzioni murarie sia moderne sia antiche (edifici, ponti, torri), nonché di vari elementi strutturali (pareti, archi e volte, pile e colonne).
Il rinforzo di archi e volte in muratura con FRP può contribuire in modo significativo a migliorare la loro portanza in stato limite, attivando meccanismi locali a livello di materiali e interfaccia, ma comporta anche un cambiamento dei meccanismi di collasso della struttura originale, dal momento che il rinforzo impedisce la tipica rottura fragile causata dalla formazione di meccanismi a cerniera.
Nonostante un crescente numero di studi riguardanti il rinforzo di strutture murarie con FRP, le indagini sono tuttavia ancora limitate, se confrontate con applicazioni su calcestruzzo armato. Inoltre, pochi codici e raccomandazioni sono attualmente disponibili.
Partendo da questi punti, il presente lavoro affronta l'indagine sperimentale di tre meccanismi locali coinvolti nel collasso di archi rinforzati con FRP: il comportamento dell’interfaccia nel caso di tensioni normali alla superficie (distacco del composito osservato in strutture rinforzate all’intradosso) è stato investigato mediante l’esecuzione di un ampio numero di prove combinate eseguite su mattoni pieni in laterizio (prove a flessione, compressione, trazione indiretta e pull-off), allo scopo di calibrare sperimentalmente eventuali correlazioni fra i relativi parametri di resistenza e di osservare eventuali influenze del tipo di fibra e della presenza del primer sul comportamento nella prova di pull-off; il comportamento nel caso di azioni tangenziali è stato studiato mediante l’esecuzione di dieci Double-lap Shear Tests su mattoni pieni in laterizio, al fine di calibrare energia di frattura e legge bond-slip per rinforzo in fibra di carbonio e fibra di vetro (inoltre, è stata proposta una semplice legge bond-slip); il comportamento nel caso di azioni miste (quattordici prove eseguite) è stato investigato mediante l’adattamento di una prova sviluppata per applicazioni di FRP su calcestruzzo armato, nota come V-shape Peel Test, a mattoni in laterizio usati come substrato, allo scopo di riprodurre a scala locale le condizioni relative allo scorrimento a taglio sul giunto di archi con rinforzo estradossale. Infine, vari casi studio, riguardanti archi e volte in muratura, a dimensioni reali oppure scalate, sono stati raccolti da letteratura al fine di comparare i risultati sperimentali con i modelli interpretativi del comportamento globale della struttura a collasso attualmente disponibili
Corpo, spazio, architettura. Fenomenologia dell’esperienza spaziale Matteo Vegetti, Fabrizia Bandi (eds.), Editrice Morcelliana, Brescia 2024
No full textThe author reviews "Corpo, spazio, architettura: Fenomenologia dell’esperienza spaziale," edited by Matteo Vegetti and Fabrizia Bandi. The book examines the philosophical underpinnings of spatial experience through a phenomenological lens, engaging with both traditional and contemporary notions of how space, body, and architecture interconnect. The author highlights the text\u27s exploration of how architects and designers might integrate phenomenological insights into their work, transforming space from mere physical dimensions into lived, experienced reality. The review appreciates the book’s thematic organization, which starts with foundational theories from Merleau-Ponty and expands through discussions on virtual spaces and the future of architecture in the digital age. Through this anthology, readers gain a comprehensive view of the architectural implications of phenomenological thought, making it a critical resource for anyone involved in the conceptualization and design of space
Le dimissioni degli amministratori locali conseguenti a intimidazioni
No full textIl contributo, incentrato sul fenomeno delle dimissioni degli amministratori locali indotte da intimidazioni e minacce, riprende e sviluppa la relazione svolta al Convegno di Pisa del 5 ottobre 2018, frutto di un Progetto di ricerca di Atene
Experimental assessment of bond behaviour of FRP on brick masonry
No full textExisting masonry structures represent a significant amount of the architectural heritage. Many of these buildings are vulnerable to earthquakes. Consequently, they need structural improvements in order to meet the seismic requirements of recent building guidelines. In the last decade, there has been a growing interest in the application of Externally Bonded Fibre Reinforced Polymers (EB-FRP) as strengthening and repair materials, due to their high-performance mechanical characteristics, feasibility of application in civil structures, resistance to chemical attacks and other potentials. Brick masonry components are the most suitable substrate susceptible to improvements, due to their more regular surface in comparison with stonework or rubble masonry. The bond behaviour of FRP applied on a masonry substrate is a critical issue for the effectiveness of the technique. In this paper, the results of an experimental campaign on the local behaviour of EB-FRP applied on clay bricks are presented. Experimental failure load results were compared with predictive bond-strength models proposed in literature for concrete substrate. On the basis of measured strengths and local deformations, interface fracture energies were calibrated and an analytical function was proposed as bond stress-slip law. Finally, a bilinear law was calibrated for practical design applications
Sharing the pie: the Lutheran is neither opportunistic nor generous
No full textThis paper studies how individual religiosity affects people's behaviour. In particular here I study the behaviour of the second players in a standard trust game. They have the possibility of sharing some resources between themselves and their game mates. It results that more religious people tend to choose an even allocation of these resources, whilst the less religious participants are either opportunistic or generous.religiosity, distribution of resources, inequity aversion
rilem 223 TC MSC Data warehouse
No full textThe MSC Data Warehouse (DWH) is a powerful tool, able to collect and compare data and results coming from experimental tests, modelling, and various applications of composites applied to masonry. Data on composite materials, reinforcing systems and masonry typology related to already published research works are described, and results obtained on single structural components and assemblages (walls, columns, arches and vaults), specific aspects (bond, durability, use of NDT) up to global behaviour and case studies are collected.
The aim is to provide a repository for data to share knowledge among researchers. But additionally, as modern tool, it permits a quick real-time comparison and elaboration of research data and results, through histograms and charts. Also output in pdf and xls formats are possible.
Therefore, it can be used to highlight needs and lacks in the field, and to direct further more aware research developments worldwide.
The DWH is completely free both for consultation and management and data entry, so experts are invited to contribute to update it continuously.
Each contributor has a own space of work for data management of a project, so inserted data are visible and available for all members only when the project is declared closed by the owner
Peel strength testing of FRP applied to clay bricks
No full textThe paper presents a preliminary local investigation related to sliding on a mortar joint due
to excessive shear force, mechanism observed during testing of masonry arches and barrel vaults reinforced
with Externally Bonded Fibre Reinforced Polymers (EB FRP) at their extrados. This activity
was aimed at evaluating a possible contribution of the FRP reinforcement to joint resistance. Fourteen
V-shape Peel Tests (VPT) have been performed, which consist in peeling off a central FRP strip
from two clay solid bricks aligned along their longitudinal axis, so that the reinforcement assumes
a typical “V” shape during detachment. Tests were designed to reproduce and isolate the reinforcement
mixed-mode debonding behaviour related to the above mentioned failure mechanism, and their
execution allowed assessing experimental setup and procedures
A DATA WAREHOUSE ON THE STRENGTHENING OF MASONRY STRUCTURES WITH COMPOSITE MATERIALS
No full textA web-based data warehouse (DW) has been developed to collect, categorize, analyse and share data on the state-of-the-art of the application of composite materials on masonry buildings. The aim of this work is to provide an adaptable and dynamic research tool to identify the most significant parameters involved and homogenise the application procedures and recommendations, still not enough comprehensive despite of the remarkable market evolution. A brief description of the selection criteria of the involved parameters is presented, followed by a detailed description of the structure, technology and output possibilities of the DW. This tool has been developed within the activity of the RILEM Technical Committee 223-MSC and is now available on-line and open to the contribution of selected public
Formal and informal sectors: Interactions between moneylenders and traditional banks in the rural Indian credit market
No full textThis paper describes, through a theoretical approach, the interactions between institutional lenders and local moneylenders, and how these affect the rural credit market. It evaluates the effects produced by the introduction of "spillovers" in a rural credit market with rationing in which banks and moneylenders interact simultaneously while working in distinct segments. Due to the strong and consolidated social ties, it is probable that the spread of knowledge concerning potential debtors comes about in targeted and rapid way with reduced costs for the lenders as well.
Multi-scale characterization of moisture and thermal cycle effects on composite-to-timber strengthening
No full textThe paper examines the influence of moisture and temperature cycles on timber elements reinforced
with a wet lay-up system composed of various fibrous materials (carbon, flax) and matrices (epoxy resin,
vinyl glue). A multi-scale experimental approach was adopted, including: (i) mechanical characterization
of the composite reinforcement systems; (ii) investigation of behavior at the composite-to-timber interface
by mechanical bond tests and microstructural analyses; (iii) four-point bending tests on strengthened
timber beams. The results highlighted the good performance of natural-fiber composites
compared with synthetic ones, and the marked influence of wood moisture content and temperature
on bonding
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