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Strengthening with composite materials is becoming more and more an effective solution for increasing the structural safety of masonry buildings, often subjected to severe degradation or potentially vulnerable to seismic events. Structural retrofitting can be performed according to different techniques, based on Fiber Reinforced Polymer (FRP) or Fiber Reinforced Cementitious Matrix (FRCM) strengthening systems. The second group of composite systems is usually preferred nowadays thanks to some important advantages such as better compatibility with the substrate, applicability on wet surfaces, fire resistance, permeability and reversibility. Several experimental and numerical studies can be found in literature concerning masonry panels strengthened with FRP and FRCM systems. The knowledge about the use of the latter, nevertheless, is still partially limited, in particular if the out-of-plane behaviour of walls is taken into account, with the experimental and numerical database available resulting mainly restricted to monotonic cases. In this framework, results of an experimental campaign devoted to the study of the out-of-plane behaviour of tuff and brick masonry walls strengthened with different types of FRCM systems will be presented and discussed in this paper, performing also a comparison with available predictive formulas. Experimental results showed, in general, good performance of FRCM composite materials, with a proper exploitation of their tensile capacity, proving their effectiveness for the out-of-plane strengthening of historical masonry walls.

Fiber Reinforced Cementitious Matrices (FRCM) are composite materials adopted nowadays for the structural strengthening of masonry structures to improve the seismic behavior. To guarantee the efficiency of the strengthening system, a proper bond between the FRCM and the masonry substrate should be ensured. For the mechanical characterization of the composite materials, indeed, bond tests are performed together with tensile tests. In the present work, numerical simulations of single-lap shear tests on carbon FRCMs applied on a brick masonry substrate are performed with the objective of calibrating a proper bond-slip law. In particular, the carbon fibers are singularly modelled, adopting a micro-modeling approach for the FRCM system. Nonlinearities are lumped into interface elements at the matrix-to-fiber interface, to reproduce the failure modes typically encountered in experimental tests, where a relative slip between the fibers and the matrix can often occur. Comparisons between numerical results and results obtained from experimental tests performed on the same FRCM systems, allowed for the calibration of bond-slip laws, which could be also implemented in the numerical modeling of experimental tests on full-scale strengthened masonry walls.

The evaluation of the safety of existing masonry constructions is a crucial and current issue, especially for countries characterized by the presence of a large number of old and ancient buildings. Within the vulnerability assessment procedures, one of the most important phases is the evaluation of the material mechanical properties. Several investigation techniques can be adopted, classified as non-destructive, minor-destructive and destructive according to their invasiveness on the construction. To determine the compressive strength of existing masonries, tests on the masonry components, bricks and mortar, can be performed. Predictive models or empiric formulations can then be used to evaluate the masonry compressive strength, starting from the mechanical properties of the constituents. The objective of the present research is to determine the capability of predictive models to effectively capture the masonry compressive strength. For this purpose, a database of experimental tests conducted on existing masonry buildings was collected, together with data from the literature. In particular, the masonry compressive strength and the strength of bricks and mortar were experimentally evaluated or derived from previous researches. The predictive models chosen were applied, using the brick and mortar properties, and the results were correlated with the masonry compressive strength, considered as a reference. The investigated masonries were classified according to their strength and different ranges were considered to better evaluate the reliability of the formulations adopted. Critical analyses about the suitability of each predictive model will be presented, with a particular focus about the determination of the compressive strength for poorquality masonries, for which a modified analytical formulation was calibrated.

A masonry pier subjected to shear can fail according to a rocking, sliding or diagonal cracking failure mode, depending on the element geometry, the acting tangential and normal stresses, the boundary conditions, and the masonry mechanical parameters [Magenes and Calvi, 1997; Calderini et al., 2009; Ferretti et al., 2019a]. With the objective of studying the shear behavior of masonry, several experimental setups were proposed, in past researches, for the execution of in-plane shear tests on masonry panels [van Vliet, 2004]. The variability of these setups, mainly related to the boundary conditions, the presence of a vertical load, and the way of application of the horizontal load to the samples, highlights the need to correctly design such systems to reproduce the desired shear failure [Ferretti et al., 2019b].

This publication is part of the proceedings of the Biot-Bažant Conference on Engineering Mechanics and Physics of Porous Materials, which took place virtually on June 1-3, 2021. It contains a one-page abstract and the video of the talk that was given at the conference.v

Le modalità di rottura di pannelli murari in presenza di azioni orizzontali sono riconducibili, come è noto, a tre diversi meccanismi: rottura per scorrimento, rottura per fessurazione diagonale, rottura per pressoflessione (rocking). Con l’obiettivo di studiare il comportamento accoppiato a taglio-compressione di pannelli in muratura, si è messo a punto un innovativo setup sperimentale per l’esecuzione di prove monotone e cicliche su pannelli murari in scala reale. In particolare, il setup è stato progettato in modo da poter applicare un carico verticale di compressione e di modularlo, al crescere dello sforzo di taglio, al fine di impedire le rotazioni della sezione superiore del pannello e, quindi, riprodurre una condizione di vincolo del tipo incastro-incastro scorrevole, tipicamente riscontrata nei pannelli murari di edifici reali soggetti all’azione sismica. Nel presente lavoro sono illustrati i risultati di diverse simulazioni numeriche con l’obiettivo di analizzare le potenzialità del sistema di prova. L’intero setup e il pannello murario sono stati modellati tramite un software a elementi finiti, considerando la muratura come materiale omogeneo, e sono state eseguite analisi non lineari per investigare le differenti modalità di rottura. Inoltre, sono state condotte analisi parametriche al fine di ottenere risultati predittivi di future prove sperimentali, variando le proprietà meccaniche della muratura. I risultati delle simulazioni numeriche hanno permesso di confermare la capacità del setup di prova di riprodurre la condizione di vincolo desiderata e quindi di analizzare la modalità di rottura per fessurazione diagonale, che tipicamente si riscontra in pannelli murari sollecitati a taglio.

A proper bond between reinforcement and concrete is key for an appropriate composite action of both materials in reinforced concrete structures. However, to-date limited studies exist on bond of fiber reinforced polymer (FRP) bars in concrete members under flexure. In this paper, the bond strength developed by FRP and steel rebars is evaluated and compared, by testing reinforced concrete beams under three point bending load. The investigation included 4 beams that were 183 cm long × 15 cm wide × 36 cm deep: two of them were reinforced with sand coated GFRP rebars, while steel was used to reinforce the other two. For each of the reinforcing systems, two different embedded lengths were tested: 30 db (380 mm) and 40 db (510 mm). The beams were tested under a 3-point-bending setup and they were monitored using several measuring devices: LVDTS, potentiometers and strain gauges. Preliminary results show that the GFRP rebars have lower bond capacity than the ones made of steel. Moreover, it was inferred that the embedded lengths suggested by actual code provisions for GFRP rebars are too conservative.

In the assessment of existing constructions for seismic vulnerability, one of the most challenging tasks is the determination of the mechanical properties of the materials. In this paper, results of an experimental campaign on rural masonry buildings are presented. Slightly-destructive and destructive tests were performed with the aim of evaluating the mechanical characteristics of masonry and providing useful indications on the methodologies and testing procedures to be applied in practice. In particular, results from what are termed “shove” tests and splitting tests on cores with inclined mortar joints will be presented and discussed, together with results of diagonal compression and shear-compression destructive tests. The failure modes observed and the parameters obtained from the different experimental tests will be analysed, with the objective of combining and comparing the outputs of the different tests, in order to evaluate the reliability of the proposed techniques.

Soil salinization is becoming worldwide one of the most serious land degradation issues. Seawater intrusion in upper aquifers is responsible for the largest proportion of salt-affected agricultural lands in coastal areas. In this study, the impact of different irrigation strategies on the salinity of a maize cultivated field located in the coastal plain of Ravenna, Italy, was simulated with the FAO AquaCrop model. Model calibration was supported by comparison with remote-sensed and field collected crop data. Ten irrigation scenarios were tested by varying the irrigation season length, the soil moisture threshold for irrigation (TI), and the irrigation depth (ID), in presence or absence of flooded pipe drains (FD) to create a fresh-water lens preventing salt rising from brackish groundwater. FD show to be more effective in countering soil salinization than strategies exclusively based on supplying enough water to obtain salt leaching (SL). The best result, in terms of both fodder maize yield and salinization control, is achieved with the combination: FD immediately after sowing, irrigation inhibited in May, TI set at 50% of soil readily available water (RAW), and ID modulated to exceed field capacity and obtain SL. The worse strategy is revealed to be the non-FD scenario, coupled with no irrigation in May and August, TI ranging between 65 and 80% of soil RAW depletion, and ID set at 50 mm. Even if water-conservative, this approach results in high soil salinization and leads to significant yield decrease.

Recent earthquakes have shown the key role of post-earthquake technical inspections aimed at assessing the seismic safety and/or usability of buildings and the functionality of infrastructural systems, in order to minimize the impact of losses on citizens as fast as possible. The AeDES form is used to evaluate the safety conditions of buildings in order to enable people to return to their social and economic activities. The ReLUIS consortium has been heavily involved in the post-earthquake emergency phase of the central Italy earthquake. Consortium support to the Department of Civil Protection consisted of technical surveys of public buildings, with emphasis on school buildings, hospitals, strategic infrastructures, and sites with historical and monumental significance. Researchers from several Italian universities carried out in situ surveys in order to reduce social hardship. Usability and damage assessment was carried out by teams of surveyors made up of experts from a list of ReLUIS researchers mobilized in accordance with emergency procedures in case of earthquake. The potential vulnerabilities of several case studies involving school complexes are discussed, and recommendations for further investigations are provided.