During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.
Masonry is a characteristic example of heterogeneous material, where stone blocks or bricks are j... more Masonry is a characteristic example of heterogeneous material, where stone blocks or bricks are joined together through mortar layers. For simple structures it is possible to consider explicitly the microstructure by using suitable models for the different phases. However, this approach is not well suited for large buildings, since it requires a significant amount of modeling and computing time. For this reasons, several continuum constitutive models have been developed, based on empirical data or numerical homogenization of the microstructure [1, 2]. A continuum model is indeed sufficient in most regions of a building, excluding those where localization occurs, as the zones near to the corners of the openings or where macroscopic cracks appear. There, the details of the microstructure may become important. A multiscale model [3, 4], which uses a homogenized continuum at the macroscopic level and a discrete model in the critical regions, should benefit of the favorable features of b...
The paper presents results of an experimental campaign on reinforced glass beams, that represent ... more The paper presents results of an experimental campaign on reinforced glass beams, that represent a safe solution for the use of glass as a structural material. A new kind of FRP reinforced glass beams, formed by three-layer laminated float glass plies and two FRP bars, is proposed. One bar is installed along the upper edge of the beam and the other along the lower edge; both bars are housed inside a “U” shape channel, that allows to bond bars on three sides. Common structural resins are utilized as adhesives, after assessing their bond strength to glass through adhesion tests and pull-out tests. The tensile FRP bar can sustain normal stresses after the glass fracture, like steel rebars in reinforced concrete beams after concrete cracking. The structural response of proposed beams was investigated through four-point bending tests under room temperature and short-term loads. Both smooth and helical wrapped (HW) bars were used as reinforcing bars, and two different types of resins were utilized to bond bars to the glass. Main experimental results are discussed, together with limitations in the application and possible improvements.
Journal of Performance of Constructed Facilities, 2017
AbstractDiscrete rigid blocks interacting through nonlinear elastic damageable interfaces are use... more AbstractDiscrete rigid blocks interacting through nonlinear elastic damageable interfaces are used to model the global behavior of a medieval masonry tower under seismic actions. The seismic vulner...
Effects of masonry infills on the seismic vulnerability of steel frames is studied through multi-... more Effects of masonry infills on the seismic vulnerability of steel frames is studied through multi-scale numerical modelling. First, a micro-modelling approach is utilized to define a homogenized masonry material, calibrated on experimental tests, which is used for modelling the nonlinear response of a one-story, single span, masonry-infilled portal under horizontal loads. Based on results of the micro-model, the constitutive behavior of a diagonal strut macro-element equivalent to the infill panel is calibrated. Then, the diagonal strut is used to model infill panels in the macro-scale analysis of a multi-span multi-story infilled moment-resisting (MR) steel frame. The seismic vulnerability of the MR frame is evaluated through a nonlinear static procedure. Numerical analyses highlight that infills may radically modify the seismic response and the failure mechanism of the frame, hence the importance of the infill correct modelling.
La memoria si pone lo scopo di valutare, alla luce delle vigenti normative, il livello di sicurez... more La memoria si pone lo scopo di valutare, alla luce delle vigenti normative, il livello di sicurezza strutturale della Rocca Strozzi a Campi Bisenzio (FI). Dopo una prima parte in cui vengono riportate una descrizione della geometria strutturale e dello stato di conservazione della Rocca, in una seconda parte sono sviluppate le verifiche di sicurezza sia nei confronti dei carichi gravitazionali sia nei confronti dell'azione sismica. La memoria si conclude individuando e descrivendo possibili interventi strutturali finalizzati al recupero funzionale e alla riduzione della vulnerabilità sismica della struttura.
IOP Conference Series: Materials Science and Engineering, 2020
In order to prevent seismic damage on building heritage built before Seismic Standards, construct... more In order to prevent seismic damage on building heritage built before Seismic Standards, constructions require to be assess to verify the structural response in the case of multi-level intensity seismic actions. This problem especially concerns those buildings with a social function as schools, hospitals, etc., or with historical and architectural value as that designed by important builders of the past. This is the case of the bar-restaurant building of “Bellariva” Sport Centre, designed and built in Florence by the World-famous Italian engineer Pier Luigi Nervi in the Sixty years. Its structure is characterized by reinforced concrete frames and hosts the locker rooms of the swimming pool and a bar on the first floor, a restaurant on the second, where a long crack was observed. The presence of a large balcony with heavy perimeter planters near the cracked zone motivated the execution of on-site tests finalized to determine the steel bars connecting the restaurant floor to the balcon...
IOP Conference Series: Materials Science and Engineering, 2019
The recent earthquakes occurred in Italy highlighted again the high vulnerability of structures b... more The recent earthquakes occurred in Italy highlighted again the high vulnerability of structures built before the release of national Seismic Standards. This induced several local authorities to undertake extensive performance assessment campaigns of public buildings, among which mainly schools. A study carried out within one of these campaigns, concerning the evaluation of seismic vulnerability and the design of retrofit interventions in a school building in Florence, is presented herein. The structure was built at the beginning of 1970s, and is characterized by a ground storey with reinforced concrete frame skeleton, and a first and second storey with steel structure. An extensive on-site experimental investigation was developed at a first step of the study, which allowed identifying the mechanical characteristics of the constituting materials, and re-drawing the main structural details. Based on these data, a check of the seismic performance in current conditions was carried out, ...
Nell'articolo viene presentata una sintesi dei risultati di una ricerca sperimentale e numeri... more Nell'articolo viene presentata una sintesi dei risultati di una ricerca sperimentale e numerica svolta, in collaborazione fra le Università di Firenze e di Buffalo (New York), sul tema dell'isolamento alla base mediante sistemi pendolari ad attrito, di tipo “Single”(SFP),“ ...
The paper presents the structural analysis performed for the reconshuction design of the Old Brid... more The paper presents the structural analysis performed for the reconshuction design of the Old Bridge (Stari Most) of Mostar, in Bosnia Herzegovina. The bridge survived for more than 400 years, from 1566 till 1993, when it was destroyed by shelling, during the conflict between the Muslims of Bosnia and the Croats. The design was developed in 2000 and 2001 under the supervision of an International Commission of Experts. In the paper brief historical notices and information about topographic and geotechnical surveys and material tests are first given, then results of numerical analyses are presented. The main aim of the structural analysis was the assessment of the load bearing capacity of the bridge for all load cases prescribed by present European Recommendations. Numerical analyses allowed putting into evidence the excellent structural performance of the bridge. The fist stone of the bridge was laid on June 27,2002.
Il presente lavoro si colloca nell'ambito degli studi volti a fornire un'interpretazion... more Il presente lavoro si colloca nell'ambito degli studi volti a fornire un'interpretazione dei dissesti che interessano gli edifici in muratura attraverso l'analisi di un caso di studio: il palazzo Bourbon-Del Monte, un palazzo nobiliare del XVII secolo sito nel comune di ...
TiO 2-coated porous silica glass tubes containing macropores were fabricated and evaluated for th... more TiO 2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K) was determined to be 4.6 × 10 −2 L µmol −1 , and the Langmuir-Hinshelwood rate constant (k LH) was calculated as 2.6 µM min −1. To determine the influence of ions on the efficiency of methylene blue degradation, we examined both Milli-Q water (soft water) and Contrex water (hard water) as solvents, and confirmed the reduced purification for the Contrex solution. It was, therefore, considered that the presence of inorganic salts decreased the photocatalytic efficiency. Furthermore, variations in the methylene blue decomposition ability were observed between anion-free and cation-free Contrex. Finally, we concluded that the efficiency of photocatalytic decomposition of TiO 2 was influenced by multiple parameters, including the presence of anions and cations, as well as the solution pH.
Abstract An experimental investigation is presented on the mechanical response of progressively d... more Abstract An experimental investigation is presented on the mechanical response of progressively damaged Laminated Glass (LG) beams assembled with modified polyvinyl butyral (PVB)-based interlayers (DG41). While it is known that ionoplast interlayers significantly improve the load-bearing capacity and residual strength of damaged LG elements, limited experimental data are available on recently developed compounds such as DG41. The role of interlayers increases with the damage level within LG elements: when glass plies break, LG stiffness and strength depend on the ability of the interlayer to couple intact glass plies and fragments of shattered ones. For damaged LG beams, the consequences of the increases in volume of a broken tempered glass plies are discussed. In particular, the interlayer activates two competing effects on the undamaged glass plies affecting the residual carrying capacity: a positive “tension-stiffening” over time and the tendency of tempered glass to expand when fractured that triggers “negative” stress/strain fields in undamaged glass plies.
Forming new openings in load-bearing masonry panels is a frequent activity in engineering practic... more Forming new openings in load-bearing masonry panels is a frequent activity in engineering practice, often accomplished through very simplified design methods despite the complexity of the mechanical behaviour of the masonry and its interaction with the frame. Scientific literature and building codes provide little information. The Italian building code and the local regulation of Tuscany give some dimensional prescriptions and basic guidelines. Different simplified design methods in the literature lead to wide-ranging results. Here, the problem is approached through nonlinear finite-element analyses. The masonry is modelled through a rotating crack constitutive model, and the interaction between steel-frame and masonry, through cohesive-frictional interface elements. Sensitivity analyses are carried out by varying geometrical and mechanical parameters and the responses are compared in terms of capacity curves. The influence of the steel-profile cross-section, the position of the opening within the wall, and the degree of connection between the steel uprights and the masonry are evaluated. The study is extended to three-dimensional structures to determine the impact of the local operation of the opening formation on global behaviour. Based on the results obtained, some indications and guidelines are proposed.
During their operation, modern aircraft engine components are subjected to increasingly demanding... more During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data.
Masonry is a characteristic example of heterogeneous material, where stone blocks or bricks are j... more Masonry is a characteristic example of heterogeneous material, where stone blocks or bricks are joined together through mortar layers. For simple structures it is possible to consider explicitly the microstructure by using suitable models for the different phases. However, this approach is not well suited for large buildings, since it requires a significant amount of modeling and computing time. For this reasons, several continuum constitutive models have been developed, based on empirical data or numerical homogenization of the microstructure [1, 2]. A continuum model is indeed sufficient in most regions of a building, excluding those where localization occurs, as the zones near to the corners of the openings or where macroscopic cracks appear. There, the details of the microstructure may become important. A multiscale model [3, 4], which uses a homogenized continuum at the macroscopic level and a discrete model in the critical regions, should benefit of the favorable features of b...
The paper presents results of an experimental campaign on reinforced glass beams, that represent ... more The paper presents results of an experimental campaign on reinforced glass beams, that represent a safe solution for the use of glass as a structural material. A new kind of FRP reinforced glass beams, formed by three-layer laminated float glass plies and two FRP bars, is proposed. One bar is installed along the upper edge of the beam and the other along the lower edge; both bars are housed inside a “U” shape channel, that allows to bond bars on three sides. Common structural resins are utilized as adhesives, after assessing their bond strength to glass through adhesion tests and pull-out tests. The tensile FRP bar can sustain normal stresses after the glass fracture, like steel rebars in reinforced concrete beams after concrete cracking. The structural response of proposed beams was investigated through four-point bending tests under room temperature and short-term loads. Both smooth and helical wrapped (HW) bars were used as reinforcing bars, and two different types of resins were utilized to bond bars to the glass. Main experimental results are discussed, together with limitations in the application and possible improvements.
Journal of Performance of Constructed Facilities, 2017
AbstractDiscrete rigid blocks interacting through nonlinear elastic damageable interfaces are use... more AbstractDiscrete rigid blocks interacting through nonlinear elastic damageable interfaces are used to model the global behavior of a medieval masonry tower under seismic actions. The seismic vulner...
Effects of masonry infills on the seismic vulnerability of steel frames is studied through multi-... more Effects of masonry infills on the seismic vulnerability of steel frames is studied through multi-scale numerical modelling. First, a micro-modelling approach is utilized to define a homogenized masonry material, calibrated on experimental tests, which is used for modelling the nonlinear response of a one-story, single span, masonry-infilled portal under horizontal loads. Based on results of the micro-model, the constitutive behavior of a diagonal strut macro-element equivalent to the infill panel is calibrated. Then, the diagonal strut is used to model infill panels in the macro-scale analysis of a multi-span multi-story infilled moment-resisting (MR) steel frame. The seismic vulnerability of the MR frame is evaluated through a nonlinear static procedure. Numerical analyses highlight that infills may radically modify the seismic response and the failure mechanism of the frame, hence the importance of the infill correct modelling.
La memoria si pone lo scopo di valutare, alla luce delle vigenti normative, il livello di sicurez... more La memoria si pone lo scopo di valutare, alla luce delle vigenti normative, il livello di sicurezza strutturale della Rocca Strozzi a Campi Bisenzio (FI). Dopo una prima parte in cui vengono riportate una descrizione della geometria strutturale e dello stato di conservazione della Rocca, in una seconda parte sono sviluppate le verifiche di sicurezza sia nei confronti dei carichi gravitazionali sia nei confronti dell'azione sismica. La memoria si conclude individuando e descrivendo possibili interventi strutturali finalizzati al recupero funzionale e alla riduzione della vulnerabilità sismica della struttura.
IOP Conference Series: Materials Science and Engineering, 2020
In order to prevent seismic damage on building heritage built before Seismic Standards, construct... more In order to prevent seismic damage on building heritage built before Seismic Standards, constructions require to be assess to verify the structural response in the case of multi-level intensity seismic actions. This problem especially concerns those buildings with a social function as schools, hospitals, etc., or with historical and architectural value as that designed by important builders of the past. This is the case of the bar-restaurant building of “Bellariva” Sport Centre, designed and built in Florence by the World-famous Italian engineer Pier Luigi Nervi in the Sixty years. Its structure is characterized by reinforced concrete frames and hosts the locker rooms of the swimming pool and a bar on the first floor, a restaurant on the second, where a long crack was observed. The presence of a large balcony with heavy perimeter planters near the cracked zone motivated the execution of on-site tests finalized to determine the steel bars connecting the restaurant floor to the balcon...
IOP Conference Series: Materials Science and Engineering, 2019
The recent earthquakes occurred in Italy highlighted again the high vulnerability of structures b... more The recent earthquakes occurred in Italy highlighted again the high vulnerability of structures built before the release of national Seismic Standards. This induced several local authorities to undertake extensive performance assessment campaigns of public buildings, among which mainly schools. A study carried out within one of these campaigns, concerning the evaluation of seismic vulnerability and the design of retrofit interventions in a school building in Florence, is presented herein. The structure was built at the beginning of 1970s, and is characterized by a ground storey with reinforced concrete frame skeleton, and a first and second storey with steel structure. An extensive on-site experimental investigation was developed at a first step of the study, which allowed identifying the mechanical characteristics of the constituting materials, and re-drawing the main structural details. Based on these data, a check of the seismic performance in current conditions was carried out, ...
Nell'articolo viene presentata una sintesi dei risultati di una ricerca sperimentale e numeri... more Nell'articolo viene presentata una sintesi dei risultati di una ricerca sperimentale e numerica svolta, in collaborazione fra le Università di Firenze e di Buffalo (New York), sul tema dell'isolamento alla base mediante sistemi pendolari ad attrito, di tipo “Single”(SFP),“ ...
The paper presents the structural analysis performed for the reconshuction design of the Old Brid... more The paper presents the structural analysis performed for the reconshuction design of the Old Bridge (Stari Most) of Mostar, in Bosnia Herzegovina. The bridge survived for more than 400 years, from 1566 till 1993, when it was destroyed by shelling, during the conflict between the Muslims of Bosnia and the Croats. The design was developed in 2000 and 2001 under the supervision of an International Commission of Experts. In the paper brief historical notices and information about topographic and geotechnical surveys and material tests are first given, then results of numerical analyses are presented. The main aim of the structural analysis was the assessment of the load bearing capacity of the bridge for all load cases prescribed by present European Recommendations. Numerical analyses allowed putting into evidence the excellent structural performance of the bridge. The fist stone of the bridge was laid on June 27,2002.
Il presente lavoro si colloca nell'ambito degli studi volti a fornire un'interpretazion... more Il presente lavoro si colloca nell'ambito degli studi volti a fornire un'interpretazione dei dissesti che interessano gli edifici in muratura attraverso l'analisi di un caso di studio: il palazzo Bourbon-Del Monte, un palazzo nobiliare del XVII secolo sito nel comune di ...
TiO 2-coated porous silica glass tubes containing macropores were fabricated and evaluated for th... more TiO 2-coated porous silica glass tubes containing macropores were fabricated and evaluated for their water-purification capacity using aqueous solutions of methylene blue. From the results of photocatalytic degradation tests at different initial methylene blue concentrations, the equilibrium adsorption constant (K) was determined to be 4.6 × 10 −2 L µmol −1 , and the Langmuir-Hinshelwood rate constant (k LH) was calculated as 2.6 µM min −1. To determine the influence of ions on the efficiency of methylene blue degradation, we examined both Milli-Q water (soft water) and Contrex water (hard water) as solvents, and confirmed the reduced purification for the Contrex solution. It was, therefore, considered that the presence of inorganic salts decreased the photocatalytic efficiency. Furthermore, variations in the methylene blue decomposition ability were observed between anion-free and cation-free Contrex. Finally, we concluded that the efficiency of photocatalytic decomposition of TiO 2 was influenced by multiple parameters, including the presence of anions and cations, as well as the solution pH.
Abstract An experimental investigation is presented on the mechanical response of progressively d... more Abstract An experimental investigation is presented on the mechanical response of progressively damaged Laminated Glass (LG) beams assembled with modified polyvinyl butyral (PVB)-based interlayers (DG41). While it is known that ionoplast interlayers significantly improve the load-bearing capacity and residual strength of damaged LG elements, limited experimental data are available on recently developed compounds such as DG41. The role of interlayers increases with the damage level within LG elements: when glass plies break, LG stiffness and strength depend on the ability of the interlayer to couple intact glass plies and fragments of shattered ones. For damaged LG beams, the consequences of the increases in volume of a broken tempered glass plies are discussed. In particular, the interlayer activates two competing effects on the undamaged glass plies affecting the residual carrying capacity: a positive “tension-stiffening” over time and the tendency of tempered glass to expand when fractured that triggers “negative” stress/strain fields in undamaged glass plies.
Forming new openings in load-bearing masonry panels is a frequent activity in engineering practic... more Forming new openings in load-bearing masonry panels is a frequent activity in engineering practice, often accomplished through very simplified design methods despite the complexity of the mechanical behaviour of the masonry and its interaction with the frame. Scientific literature and building codes provide little information. The Italian building code and the local regulation of Tuscany give some dimensional prescriptions and basic guidelines. Different simplified design methods in the literature lead to wide-ranging results. Here, the problem is approached through nonlinear finite-element analyses. The masonry is modelled through a rotating crack constitutive model, and the interaction between steel-frame and masonry, through cohesive-frictional interface elements. Sensitivity analyses are carried out by varying geometrical and mechanical parameters and the responses are compared in terms of capacity curves. The influence of the steel-profile cross-section, the position of the opening within the wall, and the degree of connection between the steel uprights and the masonry are evaluated. The study is extended to three-dimensional structures to determine the impact of the local operation of the opening formation on global behaviour. Based on the results obtained, some indications and guidelines are proposed.
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