1,720,998 research outputs found
An Efficient Reliability-based Design Approach to Reduce Rockfall Risk Below a Target Threshold
Full text linkRockfalls are expected to increase due to global warming and extreme events induced by climate change. An accurate quantification of the risk is fundamental for Administrations to predispose effective risk mitigation plans. Risk value should account for all the possible events that can occur in a specific time, i.e. for a magnitude (block volume) frequency relationship. Among structural protective measures, rockfall barriers are widely selected. Despite their design method has been almost defined, even not standardized, the widely adopted safety factors approach with fixed factors does not allow obtaining a specific probability of failure. Moreover, the event magnitude-frequency relationship is not accounted. A novel time- independent reliability-based approach has been recently conceived by the Authors, allowing obtaining the design values for a specific failure probability. The method accounts for all the possible events, integrating them in time with their probability. In this way, an increase of rockfall events can been accurately considered. The obtained barrier failure probability can be used to compute the risk reduction in a given time or, conversely, to define the maximum failure probability of a barrier that could be accepted
Costruire in alta quota. Nuove sfide e opportunità
Full text linkL’alta quota è un territorio molto vulnerabile in cui sussiste un precario equilibrio tra uomo e natura. Come tutti gli ambienti estremi, essa è il termometro del pianeta quando si parla di cambiamenti climatici, ed è caratterizzata da fenomeni naturali molto significativi dal punto di vista geologico. Per queste ragioni, il tema del costruire diventa in questo ambito un campo di sperimentazione di grande interesse che solleva questioni centrali relativamente alla presenza antropica nei contesti sensibili quali la messa in sicurezza del territorio, il rapporto con il paesaggio, la sostenibilità e la compatibilità ambientale, l’efficienza energetica, la prefabbricazione, l’organizzazione e la gestione del cantiere. Proprio per via della natura complessa e polisemica dell’alta montagna, anche le costruzioni in questo contesto non possono che essere oggetto di confronto tra tutte le figure professionali coinvolte nell’articolato processo che è la progettazione, la realizzazione e la gestione delle strutture antropiche. Il saggio propone una lettura multidisciplinare volta mettere in luce le criticità e le potenzialità degli aspetti progettuali (relativi all’ingegneria e all’architettura) che caratterizzano questo particolare ambito di lavoro, nell’ottica di sviluppare riflessioni declinabili anche in altri contesti in cui si richiede capacità di adattamento, attenzione agli aspetti ambientali e climatici, necessità di un approccio essenziale ed efficiente dell’abitare
Optimization methods for the evaluation of the parameters of a rockfall fractal fragmentation model
No full textIn rockfall events, the falling blocks impacting the slope can experience fragmentation due to their kinetic energy. This process produces new blocks, smaller than the initial ones, moving along independent trajectories. As a result, the in situ block size distribution (related to the slope face of the source area) and the rockfall block size distribution (related to the deposit) differ. The present paper proposes and compares two optimization procedures for choosing the parameters of an iterative fractal fragmentation model based aimed at describing the rockfall fragmentation process on the base of source and deposit block distributions. To discuss the effectiveness of each approach, the two distributions are considered free of uncertainties. The influence of the number of iterations and optimization approach are discussed in terms of easiness of interpretation of the results
Business intelligence for IT governance of a technology company
Full text linkManagers are required to make fast, reliable, and fact-based decisions to encompass the dynamicity of modern business environments. Data visualization and reporting are thus crucial activities to ensure a systematic organizational intelligence especially for technological companies operating in a fast-moving context. As such, this paper presents case-study research for the definition of a business intelligence model and related Key Performance Indicators (KPIs) to support risk-related decision making. The study firstly comprises a literature review on approaches for governance management, which confirm a disconnection between theory and practice. It then progresses to mapping the main business areas and suggesting exemplary KPIs to fill this gap. Finally, it documents the design and usage of a BI dashboard, as emerged via a validation with four managers. This early application shows the advantages of BI for both business operators and governance managers
NaTech risk in production plants in regions subjected to high seismicity, tornado or flooding hazard
Full text linkReliability analysis and partial safety factors approach for rockfall protection structures
No full textThe design of rockfall protection structures must consider several variables, such as the energy and the height of the impacting block. Nevertheless, the statistical distributions of these variables do not follow a predefined law. Reliability analyses aim at finding how the random nature of the parameters describing a structure affects its performance and safety. In the geotechnical framework, generally, the limit states approach is adopted, accounting for the design values of both effects of actions and resistances. The present paper proposes a solution to a time-variant reliability problem to define the design values of the parameters for net fences design, i.e. velocity, mass and trajectory height of the impacting block, accounting for the spreading of their distributions and rockfall occurrence process. The proposed approach is incorporated into the semi-probabilistic design framework and the equivalent partial safety factors of the main variables and the corresponding characteristic values are discussed. The results highlights that the values of the partial safety factors are affected by the ratios between two relevant values of the right-tail of the distributions of height and velocity, i.e. the 99th and the 95th percentiles, and by the parameters of the statistical distribution of the blocks found at the foot of the cliff
Decision making and project selection: an innovative MCDM methodology for a technology company
No full textIn the nowadays companies the attention to the decisional problems is growing, since they face with rapid changes in technology context. It is important for CEO and TOP management to take fast, fact-based and Data-Driven decisions in a such dynamic environment. Consequently, the project selection phase is recognized as crucial activity. It becomes particularly important to address the future investments, both from financial and economic point of view, and for other factors such as: The alignment with the Business needs, the technology context, other external agents and trends on the market. Moreover, a correct project selection can improve the respect of products/services time-to-market delivery with high-quality standards. The paper describes the design, development and test of a decision support system for projects ranking during the selection phase. The selection and prioritization of the projects in Portfolio is characterized by multitude of criteria and constrains. Therefore, the analysis through Multi-Criteria Decision Making (MCDM) has been carried out. The MCDM, the project selection models and Frameworks have been deeply investigated by applying PRISMA methodology in order to find an optimization to Project Portfolio problems for industrial application. Therefore, the model is designed, developed and tested using the ANP (Analytical Network Process) and Fuzzy-TOPSIS methods. The systematic literature review allowed to investigate the methodologies frequently used and applied in literature, in order to find the suitable one in this research field. This research describes an innovative methodology, easy-to-use to support the Managers in projects ranking with rapid and reliable response. The strategic objectives of the company have been analyzed and declined in Critical Success Factors. Further, a wide range of indicators have been chosen, weighted and selected. The ANP (Analytical Network Process) network has been designed and developed, with the support of Managers and Project Managers expertise in this field, in order to fine-tuning the system for the company use. After the selection of the indicators, though the Fuzzy-TOPSIS methodology the projects ranking has been performed and tested with 26 Projects carried on in FSTechnology, the tech-company within the Ferrovie dello Stato Italiane Group
Catenary mechanism in steel columns under extreme lateral loading: A basis for building progressive collapse analysis
Full text linkThe studies on progressive collapse have primarily focused on threat-independent methods, wherein a sudden column removal is suggested in codes. However, a real collapse scenario is necessarily threat-dependent. Focusing on blast- and impact-induced progressive collapses, the current study considers cases in which damage is concentrated in a single member, without resulting in complete column loss. It is demonstrated that the progressive collapse performance under specific threats can be better or worse compared to that of sudden column removal. Thus, dynamic column removal does not necessarily guarantee the most critical scenario, as the response in a damaged system can sometimes exceed expectations. A simple analytical model is proposed to describe in detail the observed phenomena and emphasizes the development of catenary forces in the columm under lateral extreme loading scenarios. The results provide a deeper insight into the progressive collapse performance of frame systems and the involved member-level resisting mechanisms
Archetypal Use of Artificial Intelligence for Bridge Structural Monitoring
Full text linkStructural monitoring is a research topic that is receiving more and more attention, especially in light of the fact that a large part our infrastructural heritage was built in the Sixties and is aging and approaching the end of its design working life. The detection of damage is usually performed through artificial intelligence techniques. In contrast, tools for the localization and the estimation of the extent of the damage are limited, mainly due to the complete datasets of damages needed for training the system. The proposed approach consists in numerically generating datasets of damaged structures on the basis of random variables representing the actions and the possible damages. Neural networks were trained to perform the main structural monitoring tasks: damage detection, localization, and estimation. The artificial intelligence tool interpreted the measurements on a real structure. To simulate real measurements more accurately, noise was added to the synthetic dataset. The results indicate that the accuracy of the measurement devices plays a relevant role in the quality of the monitoring
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