https://hdl.handle.net/10955/99 DINCI 2026-04-21T03:41:52Z https://hdl.handle.net/10955/5580 A Comprehensive analysis of hydrological benefits of low impact development techniques: experimental investigation and numerical modeling Palermo, Stefania Anna; Furgiuele, Franco; Piro, Patrizia Urban floods, recently increasing due to the combine effect of climate change and urbanization, represent a potential risk to human life, economic assets and environment. In this context, the traditional urban drainage techniques seem to be inadequate for the purpose, therefore a transition towards an innovative sustainable and resilient urban stormwater management is a valid solution. One promising strategy is the implementation of decentralized stormwater controls, also known as Low Impact Development (LID) systems that provide several benefits at multiple scales. Despite several studies demonstrated the LIDs’ capability in terms of surface runoff reduction, the transition towards a sustainable urban drainage system, which includes these techniques, seems to be very slow. One of the key scientific limiting factors can be found in the lack of comprehensive analyses able to highlight the hydrological performance and the physical processes involved in LID systems at multiple spatial scale and by considering long-term experimental data. The complexity of the physical processes, involved in each specific LIDs stratigraphy, requires modeling tools able to accurately interpret their hydraulic behaviour, as well as to correlate their hydrologic efficiency with the management of stormwater in the surrounding urban area. For these reasons, so far different empirical, conceptual and mechanistic models have been proposed, however in many of these studies, the hydrological parameters, as well as the physical ones were not properly investigated, limiting the analysis only to specific factors, or by considering literature values for the numerical modeling. Thus, principal aim of this thesis is to present a comprehensive analysis of the hydrological benefits of LID techniques by experimental investigation and numerical modeling. To achieve this goal, several analyses were carried out by considering different: LID systems, spatial scales, weather conditions, modeling investigation, as well as mathematical optimization approaches. Monitored data at the full scale implementation and laboratory measurements were used to support the numerical modeling. More in detail, first a global sensitivity analysis (GSA), based on the Elementary Effect Test (EET) was applied to a PCSWMM hydrodynamic model of the University Campus Innsbruck, which combines traditional drainage infrastructures and low impact development techniques, as Rain Gardens. In this regard, main findings have showed that soil hydraulic parameters considered in the model, (i.e., principally Soil Hydraulic Conductivity and Seepage Rate) were the most sensitive parameters. Therefore, the identification of these properties for LID systems is crucial in order to correctly evaluate their hydraulic performance. Starting from this finding the analysis of the hydrological efficiency of a full-scale extensive green roof, located at University of Calabria in Mediterranean Climate was assessed, by considering field monitored hydrological data, as well as soil hydraulic properties evaluated in lab, and a modeling analysis. Thus, first a field monitoring campaign for one year was carried out, and then hydrological performance indices on an event scale were evaluated. The findings have revealed the optimal behaviour of the specific green roof in Mediterranean climate, which presents an average value of Subsurface Runoff Coefficient of 50.4% for the rainfall events with a precipitation depth more than 8 mm. Later, to evaluate the influence of increasing values of substrate depths (6 cm, 9 cm, 12 cm, 15 cm) on green roof retention capacity, the hydraulic properties of the soil materials were first investigated in Laboratory, by the simplified evaporation method, and then considered for the implementation of the mechanistic model HYDRUS 1D. The results obtained in this phase have showed how the considered substrate depths were able to achieve a runoff volume reduction of 22% to 24%. Thus, as the outflow volume reduction achieved by increasing the soil depth was not significant, the ideal depth for specific soil substrate would be 6 centimetres. Following this study, and based on the findings obtained at building scale, next phase was focused on the analysis of hydrological effectiveness of Low Impact development solutions at largeurban scale in a south Italian case study. This investigation was carried out by considering different LID conversion scenarios by a predictive conceptual model (PCSWMM). In this regards, a specific permeable pavement and green roof, developed and installed at University of Calabria, were considered for the model implementation. Globally, modeling results have confirmed the suitability of these LID solutions to reduce surface runoff even if just a small percentage (30%) of the impervious surfaces is converted. By considering all of the findings, previous achieved by experimental and modelig investigation, it emerged that many aspects related to LIDs design and operation, as well as the choice of the facility and its location can affect the results in terms of hydraulic efficiency. In this regard, a mathematical optimization approach to consider several aspects together could be a suitable tool for designers of LID systems and experts in the field. Therefore, in the last part of the work, new Mathematical Optimization Approaches for LID techniques were evaluated. More in detail, the optimization of rainwater harvesting systems, by using TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) and Rough Set method as Multi-Objective Optimization approaches, was carried out. The results have demonstrated that these approaches could provide an additional tool to identify the ideal system. In conclusion, main findings of this thesis confirm the suitability of LID systems for urban stormwater management providing useful suggestions for their design and tools for assessing their hydrological effectiveness, analysing physical and hydrological parameters that affect their operation, introducing advanced concepts for the optimization of LID systems, therefore providing a significant and innovative contribution for the improvement of scientific research in the field and the spread of these sustainable techniques. Università della Calabria. Dipartimento di Ingegneria Civile. Dottorato di ricerca in Ingegneria Civile e Industriale. Ciclo XXXII 2020-03-05T00:00:00Z https://hdl.handle.net/10955/5568 Post-failure analysis of landslides using the material point method Pugliese, Luigi; Furgiuele, Franco; Troncone, Antonello Slope stability analysis is undoubtedly one of the most complex problems that civil engineers deal with. The evolution of deformation mechanisms of slopes is commonly schematized in four different stages: pre-failure, failure, post-failure and eventual reactivation. Traditional numerical methods, such as the finite element method and the finite difference method, are commonly employed to analyze the slope response in the pre-failure and failure stages under the hypothesis of small deformations. On the other hand, these methods are unsuitable for simulating the post-failure behavior due to the occurrence of large deformations. However, an adequate analysis of this latter stage and a reliable prediction of the landslide kinematics could be particularly useful for minimizing the associated risk or to establish the most suitable mitigation measures for land protection. Among the numerical techniques which have been recently developed to overcome the above-mentioned limitation, the material point method (MPM) is employed in this dissertation to analyze the post-failure stage of two real landslides: the Senise landslide (Basilicata) and the Maierato landslide (Calabria), both in Southern Italy, occurred in 1986 and 2010, respectively. The numerical analyses allow to faithfully simulate the real phenomena. In particular, with referring to the Senise landslide, the numerical analysis provides results that match satisfactorily well the field observations when both the slip surfaces detected by the installed inclinometers are accounted for. Besides, the lowest values of the shear strength parameters obtained from the laboratory tests have to be used. Moreover, an improvement of results is gained accounting for the presence of the existing structures as well. Concerning the Maierato landslide, symbol of the hydrogeological instability in Calabria (Southern Italy), the analysis performed using the material point method allows to successfully simulate the observed phenomenon, despite the complexity of this landslide regarding its size, catastrophic failure and long run-out distance. The obtained results demonstrate that an adequate analysis of the post-failure stage can lead to a better understanding of the complex mechanical mechanisms that characterize some landslides, and therefore help significantly to establish the most effective stabilization measures. UNIVERSITÀ DELLA CALABRIA Dipartimento di Ingegneria Civile Dottorato di Ricerca in Ingegneria Civile e Industriale XXXII CICLO 2020-03-05T00:00:00Z https://hdl.handle.net/10955/5554 Analysis of nonlinear phenomena in heterogeneous materials by means of homogenization and multiscale techniques Pranno, Andrea; Critelli, Salvatore; Bruno, Domenico; Greco, Fabrizio Over the past decade, scientific and industrial communities have shared their expertise to improve mechanical and structural design favoring the exploration and development of new technologies, materials and ad-vanced modeling methods with the aim to design structures with the highest structural performances. The most promising materials used in many advanced engineering applications are fiber- or particle-rein-forced composite materials. Specifically, materials with periodically or randomly distributed inclusions embedded in a soft matrix offer excel-lent mechanical properties with respect to traditional materials (for in-stance, the capability to undergo large deformations). Recent applica-tions of these innovative materials are advanced reinforced materials in the tire industry, nanostructured materials, high-performance structural components, advanced additive manufactured materials in the form of bio-inspired, functional or metamaterials, artificial muscles, tunable vi-bration dampers, magnetic actuators, energy-harvesting devices when these materials exhibit magneto- or electro-mechanical properties. To-day the scientific community recognizes that, to develop new advanced materials capable of satisfying increasingly restrictive criteria, it is vital fully understanding the relationship between the macroscopic behavior of a material, and its microstructure. Composite materials are charac-terized by complex microstructures and they are commonly subjected also to complex loadings, therefore their macroscopic response can be evaluated by adopting advanced strategies of micro-macro bridging, such as numerical homogenization and multiscale techniques. The aim of this thesis is to provide theoretical and numerical methods able to model the mechanical response of heterogeneous materials (fiber- or particle-reinforced composite materials) in a large deformation context predicting the failure in terms of loss of stability considering also the interaction between microfractures and contact. In the past literature, several theories have been proposed on this topic, but they are preva-lently limited to the analysis of microscopic and macroscopic instabili-ties for not damaged microstructures, whereas the problem of interac-tion between different microscopic failure modes in composite materi-als subjected to large deformations in a multiscale context still has not been investigated in-depth and it represents the main aspect of novelty of the present thesis. The thesis starts with a literature review on the previously announced topic. Then, the basic hypotheses of the numerical homogenization strategy are given together with a review of the most recurring mul-tiscale strategies in the modeling of the behavior of advanced composite materials following a classification based on the type of coupling be-tween the microscopic and the macroscopic levels. In addition, a theo-retical non-linear analysis of the homogenized response of periodic composite solids subjected to macroscopically uniform strains is given by including the effects of instabilities occurring at microscopic levels and the interaction between microfractures and buckling instabilities. Subsequently, the numerical results obtained were reported and dis-cussed. Firstly, the interaction between microfractures and buckling instabili-ties in unidirectional fiber-reinforced composite materials was investi-gated by means of the nonlinear homogenization theory. In such mate-rials, the investigated interaction may lead to a strong decrease in the compressive strength of the composite material because buckling causes a large increase in energy release rate at the tips of preexisting cracks favoring crack propagation or interface debonding. Thus, mi-crocracked composite materials characterized by hyperelastic constitu-ents and subjected to macrostrain-driven loading paths were firstly in-vestigated giving a theoretical formulation of instability and bifurcation phenomena. A quasi-static finite-strain continuum rate approach in a variational setting has been developed including contact and frictionless sliding effects. It worth noting that, the above developments show that non-standard self-contact terms must be included in the analysis for an accurate prediction of microscopic failure; these terms are usually ne-glected when contact is modelled in the framework of cohesive inter-face constitutive laws. The influence of the above-mentioned non-standard contributions on the instability and bifurcation critical loads in defected fiber-reinforced composites can be estimated in light of the results which will be presented in this thesis. Thus, the role of non-standard crack self-contact rate contributions to the stability and non-bifurcation conditions was pointed out by means of comparisons with simplified formulations and it was clearly shown that these contribu-tions have a notable role in an accurate prediction of the real failure behavior of the composite solid. Secondly, two multiscale modeling strategies have been adopted to an-alyze the microstructural instability in locally periodic fiber-reinforced composite materials subjected to general loading conditions in a large deformation context. The first strategy is a semiconcurrent multiscale method consisting in the derivation of the macroscopic constitutive re-sponse of the composite structure together with a microscopic stability analysis through a two-way computational homogenization scheme. The second approach is a novel hybrid hierarchical/concurrent mul-tiscale approach able to combine the advantages inherent in the use of hierarchical and concurrent approaches and based on a two-level do-main decomposition; such a method allows to replace the computation-ally onerous procedure of extracting the homogenized constitutive law for each time step through solving a BVP in each Gauss point by means of a macro-stress/macro-strain database obtained in a pre-processed step. The viability and accuracy of the proposed multiscale approaches in the context of the microscopic stability analysis in defected compo-site materials have been appropriately evaluated through comparisons with reference direct numerical simulations, by which the ability of the second approach in capturing the exact critical load factor and the boundary layer effects has been highlighted. Finally, the novel hybrid multiscale strategy has been implemented also to predict the mechanical behavior of nacre-like composite material in a large deformation context with the purpose to design a human body protective bio-inspired material. Therefore, varying the main micro-structural geometrical parameters (platelets aspect ratio and stiff-phase volume fraction), a comprehensive parametric analysis was performed analyzing the penetration resistance and flexibility by means of an in-dentation test and a three-point bending test, respectively. A material performance metric, incorporating the performance requirements of penetration resistance and flexibility in one parameter and called pro-tecto-flexibility, was defined to investigate the role of microstructural parameters in an integrated measure. The results have been revealed that advantageous microstructured configurations can be used for the design and further optimization of the nacre-like composite material. Università della Calabria. Dipartimento di Ingegneria Civile Dottorato di Ricerca in Scienze e Ingegneria dell’Ambiente delle Costruzioni e dell’Energia CICLO XXXII 2020-06-07T00:00:00Z https://hdl.handle.net/10955/5553 La valutazione della vulnerabilità sismica degli edifici storici in muratura mediante diversi approcci Porzio, Saverio; Critelli, Salvatore; Oliverio, Renato Sante Le costruzioni in muratura rappresentano gran parte del tessuto costruito e la loro salvaguardia riveste un ruolo sociale e culturale primario. Basti pensare che molti di questi edifici – quali chiese, palazzi, castelli, torri – si pongono come simboli delle città in cui riconoscersi e riconoscere le città stesse. L’interesse di studiosi e ricercatori è, dunque, rivolto alla definizione di strumenti utili alla valutazione della vulnerabilità sismica delle costruzioni storiche in muratura. Vari metodi sono attualmente in uso per la valutazione sismica dei manufatti murari, così come diversificate sono le strategie per simulare il comportamento meccanico dei materiali costituenti. Ai consolidati metodi grafici per la valutazione della sicurezza statica degli archi, volte e cupole, si sono aggiunti nuovi modelli di analisi favoriti dall’introduzione del calcolo numerico. Questo lavoro di tesi mira a valutare il comportamento delle costruzioni storiche in muratura attraverso alcuni dei diversi approcci attualmente impiegati e convalidati dalla comunità scientifica. Gli studi eseguiti partono dall’analisi di alcuni degli elementi costitutivi maggiormente rappresentativi in un edificio, quali volte e pareti, per proseguire con analisi globali attuate con differenti strategie di modellazione. Relativamente alle analisi locali, le indagini sulle volte composte – vale a dire quelle originate dall’intersezione di due volte a botte – sono state svolte in termini statici applicando le teorie dell’analisi membranale, mentre per le pareti murarie si è valutata la loro risposta nei confronti delle azioni fuori dal piano al fine di evidenziarne il contributo nella risposta sismica d’insieme del fabbricato. Riguardo alle analisi globali, uno dei principali strumenti per la valutazione della risposta sismica è rappresentato dall’analisi statica non lineare, chiamata anche analisi pushover, la quale abbina accuratezza dei risultati ad un non eccessivo tempo di calcolo. Tuttavia, nelle strutture più irregolari, l’utilizzo degli approcci canonici – che richiedono la lettura degli spostamenti solo di alcune parti del fabbricato – può portare a risultati completamente inesatti, sia a causa dell’insorgenza dei meccanismi locali di collasso che alla differente risposta della costruzione in relazione alle sue capacità duttili a livello locale. Quest’ultimo aspetto compete al tracciamento della curva di capacità della struttura che avviene, generalmente, considerando un unico punto di controllo: se questo si sposta poco, relativamente breve sarà il ramo della curva elasto-plastico dell’oscillatore equivalente; e viceversa. È per tale ragione che si è sviluppata una metodologia consistente nel considerare diversi punti di controllo, non scelti a priori, ma suggeriti dallo stato di danneggiamento individuato dalle simulazioni numeriche. All’interno della metodologia proposta, è stata definito un nuovo strumento grafico di rappresentazione degli spostamenti dei punti di controllo: l’evoluzione del danno è mostrata utilizzando delle sfere, i cui raggi sono proporzionali agli spostamenti rilevati ed il cui baricentro ha le stesse coordinate del punto di controllo che rappresenta. Le dimensioni delle sfere possono fornire informazioni sul danno occorso e sulla posizione dei punti deboli della struttura investigata, diventando così uno strumento utile per orientare le decisioni sulla tecnica di rinforzo strutturale più adeguata. La validazione della metodologia proposta è avvenuta confrontando – per un caso studio reale consistente in una costruzione di forma triangolare realizzata esclusivamente in muratura – i valori di accelerazione spettrale ottenuti mediante tutte le tipologie di approcci impiegati: dall’individuazione del moltiplicatore dei carichi mediante il teorema cinematico dell’analisi limite, applicato sul meccanismo di collasso fuori piano ritenuto più significativo, all’analisi dinamica non lineare eseguita prendendo in considerazione un accelerogramma artificiale spettro-compatibile, passando per la già citata analisi statica non lineare. I risultati mostrano una comparabilità di valori per gli approcci numerici evidenziando, invece, una discrepanza con quelli analitici a causa di diversi fattori, fra cui la non-raffinatezza dei metodi semplificati. Tuttavia, si sono dedotte informazioni dettagliate sul comportamento strutturale generale dell’edificio, nonché sulla sua sicurezza sismica. Il sommario della tesi comprende quanto segue: Capitolo 1 – Introduzione (argomenti trattati dalla tesi, revisione della letteratura, obiettivi e campo di applicazione); Capitolo 2 – illustra alcune applicazioni effettuate mediante le trattazioni analitiche discusse nello studio dello stato dell’arte; Capitolo 3 – riporta le investigazioni sismiche di alcuni casi studio basate sulla modellazione a telaio equivalente, con un’ultima parte dedicata all’utilizzo di tale strategia di modellazione per le analisi di vulnerabilità su scala territoriale attraverso l’utilizzo delle schede CARTIS-ReLUIS; Capitolo 4 – riporta le analisi numeriche basate sull’approccio FEM e la metodologia pushover a punti di controllo multipli messa a punto per l’analisi delle costruzioni con geometria irregolare in pianta; Note conclusive – presenta le conclusioni più importanti a cui si è giunti attraverso questa tesi, tra cui alcune tabelle utili ad orientare il professionista verso la scelta della strategia di valutazione più indicata per il particolare caso studio da analizzare. Masonry buildings are the main part of the building heritage and their preservation has a primarily social and cultural role. Many of these buildings – such as churches, palaces, castles, and towers – are recognizable and representative symbols of their cities. Therefore, practitioners and researchers are interested in defining useful tools for the evaluation of the seismic vulnerability of historic masonry buildings. Various methods are currently being used for the seismic assessment of masonry artifacts, as well as several strategies for simulating the mechanical behavior of materials being available. The introduction of numerical calculation has led to new analysis models, which support the graphical methods used for evaluating the static safety of arches, vaults, and domes. This thesis aims to evaluate the behavior of historic masonry structures by using some of the different approaches currently used and validated by the scientific community. The studies start from the analysis of some typical elements of a building, such as vaults and walls. Afterwards, global analyses are implemented with different modeling strategies. Regarding the local analyses: the investigations on compound vaults – namely those originating from the intersection at right angles of two barrel vaults – are carried out in a static framework by applying the membrane theory; while the out-of-plane response of masonry walls is evaluated in order to highlight their contribution in the overall seismic response of the building. Among the global analyses, the non-linear static analysis – also called pushover analysis – is one of the main tools for the evaluation of the seismic response of a building because it combines results accuracy with a reduced computational burden. However, the use of canonical approaches - which require the reading of the displacements of only some building points - can lead to inaccurate results in the most irregular structures. This is due both to the onset of local collapse mechanisms and to the different building response concerning its local ductile capabilities. These aspects are related to the capacity curve of the structure, which plots the displacements of a single control point: a short elastoplastic branch of the bilinear curve in the case of small displacements; and vice-versa. For this reason, a coupled numerical-geometrical methodology – to represent the results arising from pushover analysis – is developed by considering an appropriate number of control points, not set a priori but suggested by the state of damage detected through numerical simulations. A new graphic tool is defined to represent the displacements of the control points, and the damage evolution is shown by using spheres in which their radiuses are proportional to displacements detected, whereas each centroid has the same coordinates as the control point which it represents. The spheres’ dimensions can provide information about the damage occurred and the position of weak points of the investigated structure, so becoming a useful tool to orientate decisions about structural strengthening technique. In order to validate the proposed methodology, a comparison between the spectral acceleration values obtained through all approaches used is carried out, taking into account a real case study consisting of a triangular construction entirely made in masonry. These accelerations are based on:  the load multiplier obtained from the most significant out-of-plane collapse mechanism is defined by means of the kinematic theorem of the limit analysis;  the nonlinear dynamic analysis performed by considering an artificial spectrum-compatible accelerogram;  the above nonlinear static analysis. The results showed comparable values for numerical approaches, highlighting a discrepancy instead with the analytical ones due to various factors, including the non-refinement of simplified methods. However, detailed information on the structural behavior of the building, as well as its seismic safety, are drawn clearly. The (summary) thesis comprises the following: Chapter 1 - Introduction (thesis topics, literature review, aims and scope); Chapter 2 - illustrates some analytical applications on compound vaults and out-of-plane mechanisms of masonry façades; Chapter 3 - reports the seismic investigations of some case studies based on equivalent frame modeling, with the last part dedicated to the use of this modeling strategy in the seismic vulnerability assessment at the territorial scale by using of CARTIS-ReLUIS forms; Chapter 4 - reports the numerical analyses based on the FEM approach and the multi-control point pushover methodology developed to assess irregular buildings; Concluding remarks - presents the most important conclusions reached through this thesis, including some useful tables to guide the practitioner towards the choice of the most suitable evaluation strategy for a particular case study. Università della Calabria. Dipartimento di Ingegneria Civile. Dottorato di ricerca in Scienze ed Ingegneria dell'Ambiente, delle Costruzioni e dell'energia. Ciclo XXXII 2020-04-16T00:00:00Z