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The cast in place floors of existing buildings realized in Italy in the ‘60–70’ years are commonly made by longitudinal beams and hollow clay bricks with a top deck without internal reinforcement. Thus, they are unable to properly guarantee the load distribution function over structural members which is strongly required in case of seismic actions. Furthermore, the deck thickness of such horizontal structures is commonly less than the minimum value given by current codes (≥40 mm) in order to assume the floor as rigid in plan. The effectiveness of an innovative system, based on the use of Fibre-Reinforced Cementitious Composite (FRCC), is investigated in the paper as a strengthening technique of these existing floors. Three point bending tests on two full scale cast in place reinforced concrete (r.c.) floors have been carried out: one specimen was tested in the ‘‘as built’’ configuration; one specimen was strengthened with a new FRCC deck, about 2 cm thickness made by fibre-reinforced, shrinkage-compensated, high-strength, high-ductility, highly-fluid cementitious mortar. The main aspects related to the application procedure of the system, the experimental test setup, as well as the experimental results in terms of crack pattern, strength and deformation of the specimens are herein presented and discussed.

The effectiveness of Fibre Reinforced Cementitious Mortar (FRCM) as strengthening technique of masonry structures under seismic actions has been widely investigated by means of diagonal compression tests in the last decade. The results showed that the effectiveness of FCRM solution, based on the use of FRP grid embedded in mortar matrix, to increase the masonry walls shear capacity strongly depends on the axial stiffness of mesh reinforcement and on the mechanical properties of the matrix. The paper presents preliminary experimental results of tests carried out on specimens strengthened with a new strengthening solution based on the use of Fibre Reinforced Mortar (FRM) without the use of FRP grid. In particular, the strengthening system consists of an innovative high performance and high ductility mortar made by a mix of fibres spread in lime-based powder. The experimental program aims at investigating the soundness of such technique to increase the shear capacity of different masonry panels. In particular, the system was applied over limestone masonry walls with irregular texture, typical of existing buildings in Central Italy, and old-type clay brick masonry panels with regular texture, typical of existing buildings in the Northern Italy

In last decades, several experimental tests were carried out in order to investigate the effectiveness of strengthening systems by using FRP as a confinement technique of masonry columns. Recently, in order to solve problems related to the compatibility of FRPs with masonry members, a new technique based on the use of inorganic matrix rather than resins has been developed (FRCM-Fabric Reinforced Cementitious Matrix). In order to investigate the structural effectiveness of FRCM systems, an experimental program was carried out on full-scale masonry columns by means of uni-axial compression tests. In particular, the effectiveness of FRCM systems based on the use of A.R. glass fibre grid embedded in lime-based mortar with high mechanical properties has been investigated. Test programme, material mechanical properties, and test setup are herein presented along with the preliminary experimental results in terms of load and ductility capacity of a control and strengthened specimen. A preliminary comparison between the performance of FRP and the strengthening systems is also reported.

A study on the dynamic response of one-story building, made by yellow regular Neapolitan blocks and mortar with poor mechanical properties in a traditional texture of existing masonry structures is herein illustrated. The seismic response of the masonry building has been investigated by means of shake-table tests on 1/2-scale model. Seismic inputs of recent earthquakes Italy (e.g. L’Aquila 2009, Amatrice 2016) were used in order to investigate the seismic behavior of the sample. The paper reports the main aspects related to the specimen design procedure, the experimental test setup, experimental outcomes, crack patterns and failure mechanism of the as-built specimen.

Le strutture in muratura portante rappresentano una tra le tipologie costruttive più diffuse nell'ambito del patrimonio edilizio esistente. Purtroppo, l'esperienza acquisita con i recenti terremoti ha messo in luce la vulnerabilità di tali manufatti. Pertanto, il miglioramento sismico di strutture esistenti diventa oggigiorno di vitale importanza, sia per la salvaguardia della vita delle persone sia per la conservazione di edifici di interesse storico-monumentale. In questo campo le tecniche tradizionali di intervento non sempre soddisfano le esigenze strutturali e le esigenze di conservazione, in conformità alle più stringenti regole della moderna cultura del restauro. In questi casi, l'impiego di tecniche innovative può essere utile per risolvere alcune criticità. Il miglioramento delle performance strutturali può essere perseguito attraverso lo sviluppo di sistemi di rinforzo basati su materiali innovativi e tecniche che risultano essere chimicamente, fisicamente e meccanicamente compatibili con i materiali esistenti. La presente tesi si pone come obiettivo principale l'analisi del comportamento di strutture in muratura nei confronti di azioni sismiche. Sulla base della risposta sismica di tali elementi si indaga l'efficacia di tecniche di intervento innovative, atte a ridurrene la vulnerabilità. Lo scopo è stato perseguito mediante la progettazione e l'esecuzione di prove sperimentali su elementi, subassemblaggi e strutture in scala reale e ridotta, testate in condizioni non rinforzate e rinforzate con sistemi in composito di ultima generazione. In particolare si sono investigati alcune tra le più diffuse problematiche relative alle strutture esistenti in muratura: comportamento di un martello murario soggetto ad azioni fuori piano, rinforzato con cuciture armate mediante tubi pultrusi cavi in fibra di carbonio e iniezione di malta di calce; comportamento di pannelli murari soggetti ad azioni nel piano, rinforzati con sistemi in FRCM (Fibre Reinforced Cementitious Matrix); comportamento di colonne in muratura in scala reale soggette a carichi gravitazionali, confinate con differenti sistemi in FRCM con o senza la presenza di rinforzo interno mediante barre pultruse in GFRP o barre in acciaio inox elicoidali; comportamento globale mediante prove su tavola vibrante di un edificio in muratura tipico dell'area mediterranea in scala 1:2, rinforzato con differenti tecniche innovative a seguito del danno prodotto. Le tecniche di intervento adottate, oltre ad assolvere la propria funzione di mitigazione del rischio sono risultate idonee a risolvere i problemi emersi nel corso degli anni a causa dell'adozione di tecniche tradizionali, offrendo risultati soddisfacenti sia dal punto di vista della sicurezza strutturale che della compatibilità al supporto murario e nell'ottica della sostenibilità dell'intervento. Ciò potrà consentire in futuro la calibrazione di opportune formulazioni teoriche da inserire in documenti pre-normativi e/o normativi al fine di rendere gli interventi con tali tecniche facilmente adottabili e progettabili dai professionisti del settore.

The effectiveness of FRP systems as a confinement technique to strengthen masonry columns has been widely investigated in the last decades. Recently, a new technique, Fabric Reinforced Cementitious Matrix (FRCM), based on the use of fibrous nets embedded in inorganic matrix, has been developed and investigated as a strengthening solution in masonry buildings. Actually, the number of experimental tests on masonry columns confined by using FRCM systems is very limited, especially for real scale specimens. To fill such gap an experimental program aimed at investigating the behaviour of full scale columns made of limestone masonry blocks confined with different FRCM systems has been carried out. The results of four uniaxial compression tests are illustrated and discussed. The used FRCM systems are made with glass and basalt dry nets embedded in a lime-based mortar. The influence of transverse confinement by using internal reinforcement in forms of pultruded GFRP bars has been also investigated. The mechanical properties of the confined specimens resulted increased in terms of load-carrying capacity and ultimate axial strain.

Existing masonry buildings often exhibit a brittle behavior during seismic events due to the reduced in-plane shear capacity of piers. Inorganic composite materials are widely used for the seismic upgrading of masonry walls capacity, thanks to the good breathability and compatibility with the substrate. This work presents the results of an experimental program carried out on 17 limestone masonry panels with irregular texture typical of L’Aquila area and tested under diagonal compression. Three panels were used as control specimens; the remaining panels were strengthened with Fiber Reinforced Cement Mortar (FRCM) with anchors and two different lime-based mortars, one cement-free and one with a small cement content ratio, and coupled with two different grids (GFRP grid 40 × 40 mm and BFRP grid 6 × 6 mm). Single-sided and double-sided strengthening configurations were adopted, to investigate the reduction in strengthening effectiveness in the case of single-sided applications. The results showed that the FRCM system allowed a capacity increase by 65% in single-sided configuration and 140% in double-sided configuration. The matrix cement-content did not affect significantly the results. Conversely, the use of the BFRP grid, characterized by a 6 mm spacing, promoted the development of premature delamination problems.

Recent studies, as well as past earthquake experience, demonstrated that slender unreinforced masonry infills are significantly vulnerable with respect to out-of-plane actions. The out-of-plane collapse of infills significantly increases the repairment and refurbishment costs after earthquakes of reinforced concrete buildings and, above all, is highly detrimental for human life safety. For this reason, the interest on the experimental and numerical studies dedicated to the assessment of the effectiveness of out-of-pane repairing, strengthening and reinforcement techniques of masonry infills is growing, especially in recent years. In this work, experimental tests performed at the Department of Structures for Engineering and Architecture of University of Naples Federico II to characterize the out-of-plane response of one-way spanning unreinforced and reinforced masonry infills are presented. Namely, an out-of-plane test is performed on an “as-built” specimen, whose performance is compared with the experimental response of specimens strengthened by applying two different techniques, a fiber reinforced polymer and a fabric reinforced cementitious mortar. In addition, after test, the as-built specimen is repaired by applying the fiber reinforced polymer and tested again. The response of the repaired specimen is presented and discussed.