Structural Safety Research Papers - Academia.edu (original) (raw)

AI concepts and technologies can assist engineers in safety management by providing new software components to the existing information systems, such as real-time interpretation systems linked to the data acquisition units, qualitative... more

AI concepts and technologies can assist engineers in safety management by providing new software components to the existing information systems, such as real-time interpretation systems linked to the data acquisition units, qualitative models, and reasoning agents supporting the off-line management of information and interpretation.
In this article, we describe four decision - support systems that use such concepts and technologies to better manage the safety of civil engineering structures. During the last six years, the software development unit of ISMES -an R &D company involved in structural and mechanical engineering, environmental and land -use engineering, and information and communication technologies -has focused on AI applications to structural safety. We have addressed two main problems: the safety management of dams and monuments and the seismic risk assessment of buildings.
This led to the development of the four systems: Mistral, Damsafe, Kaleidos, and Igor.
We exploit AI tools for designing intelligent modules of our support systems, including causal networks of processes, qualitative modeling, model -based reasoning, and hierarchical object-oriented representations.
The systems also employ AI techniques such as rule -based systems, pattern matching, and neural networks, in conjunction with conventional techniques, to implement these representation and reasoning schemes.

Secondary elements such as barriers, sidewalks, and diaphragms may increase the load carrying capacity of girder bridges. This in turn affects reliability. The objective of this study is to evaluate the potential benefit of secondary... more

Secondary elements such as barriers, sidewalks, and diaphragms may increase the load carrying capacity of girder bridges. This in turn affects reliability. The objective of this study is to evaluate the potential benefit of secondary elements on the system reliability of girder bridges, if these elements are designed with the structural system to participate resisting vehicular live loads. Simple span,

This paper proposes a methodology to apply Bayesian networks to structural system reliability reassessment, with the incorporation of two important features of large structures: (1) multiple failure sequences, and (2) correlations between... more

This paper proposes a methodology to apply Bayesian networks to structural system reliability reassessment, with the incorporation of two important features of large structures: (1) multiple failure sequences, and (2) correlations between component-level limit states. The proposed method is validated by analytical comparison with the traditional reliability analysis methods for series and parallel systems. The Bayesian network approach is combined with the branch-and-bound method to improve its efficiency and to facilitate its application to large structures. A framed structure with multiple potential locations of plastic hinges and multiple failure sequences is analyzed to illustrate the proposed method.

The paper presents the nonlinear analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The response from the nonlinear analysis was considered taken the deterministic calculation procedures. The... more

The paper presents the nonlinear analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The response from the nonlinear analysis was considered taken the deterministic calculation procedures. The dynamic load is defined in time on base of the airplane impact simulations considering the real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

The calibration methods are applied to define the optimal code format according to some target safety levels. The calibration procedure can be seen as a specific optimization process where the control variables are the partial factors of... more

The calibration methods are applied to define the optimal code format according to some target safety levels. The calibration procedure can be seen as a specific optimization process where the control variables are the partial factors of the code. Different methods are available in the literature, but the choice of an appropriate method is not usually an easy task. Each method can be shown to have a better performance for a particular kind of problems. The scope of this paper is to underline the advantages and disadvantages of the classical methods, to define their domain of validity and to propose new efficient methods. In our approach, the accuracy is balanced with time efficiency by the mean of iterative scheme using approximate methods. The presented ideas are clarified by four numerical examples of parabolic performance function, column buckling, stability of submarine shells and structural elements.

There is a need for efficient bridge evaluation procedures. A considerable number of existing bridges in the United States require repair and/or replacement. Accurate estimate of the current strength and the remaining life time is... more

There is a need for efficient bridge evaluation procedures. A considerable number of existing bridges in the United States require repair and/or replacement. Accurate estimate of the current strength and the remaining life time is essential for optimum distribution of the available limited resources. The major parameters which determine the structural performance are random variables. Statistical models of load and resistance can be derived from the test data, observations and analysis. For bridge members the reliability can be calculated using this available data, observations and analysis. considerable discrepancy between the reliability level of individual members and the overall bridge reliability. Due to load sharing and redundancies, the actual load-carrying capacity often exceeds the theoretical value. System reliability methods allow us to reveal an actual safety reserve in the structure. This paper summarizes the practical bridge reliability models. Using a special sampling technique, the reliability is evaluated for typical girder bridges.

Il presente contributo è basato sull’idea che la ricostruzione di una crisi strutturale (semplice rottura o collasso vero e proprio) sia basata su una chiara, corretta, e profonda conoscenza e comprensione delle basi di progetto che... more

Il presente contributo è basato sull’idea che la ricostruzione di una crisi strutturale (semplice rottura o collasso vero e proprio) sia basata su una chiara, corretta, e profonda conoscenza e
comprensione delle basi di progetto che portano alla concezione di una costruzione e del processo di analisi che ne verifica la sicurezza e le prestazioni.
Partendo da questa idea, l’articolo cerca di presentare in modo sintetico, ma ordinato, nell’introduzione l’orizzonte temporale e la traiettoria di vita che una costruzione può esperire, evidenziando nel successivo paragrafo il carattere sistemico di una struttura, ovvero enfatizzando la organizzazione gerarchica degli elementi strutturali che la formano: da questa ultima descrizione, si possono coerentemente valutare i livelli di crisi che si possono manifestare, giudicarne la gravità e indagarne i motivi.
Successivamente, una riflessione necessaria riguarda la natura delle azioni che possono cimentare una costruzione, con le loro origini e caratteristiche in termini di intensità, probabilità
di accadimento e gravità di conseguenze. Questo è un aspetto delicato, che dà il giusto rilievo agli accadimenti e agli approcci di analisi e di indagine necessari: questo punto è analogo all’idea che in una costruzione non tutti gli elementi hanno le stesse caratteristiche e la stessa importanza. Queste considerazioni generali non appaiono adeguatamente rimarcate dal quadro normativo corrente, spesso più attivo nelle descrizioni di dettaglio.
Nel quarto paragrafo, si esamina la complessità di un problema strutturale (adattando uno schema noto in letteratura dai lavori di Perrow) e i differenti tipi di situazioni di progetto: evolutivo o innovativo. Questa distinzione è importante al fine di rendersi conto delle conoscenze
(competenze) che si devono avere nell’affrontare il progetto: competenze che se mancanti o deficitarie possono essere origine di crisi strutturali.
Esaminati seppur brevemente questi punti (orizzonte temporale e prestazionale di una struttura, sua organizzazione sistemica, natura delle azioni che possono cimentarla, possibili ragioni della complessità del problema strutturale associato), nel quinto paragrafo, si riporta il modello generale della genesi e dello sviluppo di un fallimento strutturale secondo Reason.
L’ultimo paragrafo fornisce, infine, indicazioni sulla ricostruzione dell’evento e la risalita alle responsabilità dal punto di vista ingegneristico.

Nowadays, there are many new methods for slope stability analysis; including probabilistic methods assessing geotechnical uncertainties to develop safety factors. In this paper, a reliability index analysis for the Sungun copper mine... more

Nowadays, there are many new methods for slope stability analysis; including probabilistic methods assessing geotechnical uncertainties to develop safety factors. In this paper, a reliability index analysis for the Sungun copper mine slope stability is evaluated based on three methods of uncertainties consisting Taylor series method, Rosenblueth point estimate method and Monte-Carlo simulation method. Sungun copper mine will be one of the Iran’s biggest mines with final pit’s height of 700 meters. For this study two of its main slopes were assessed, one dipping to the NE (030) and the other to the SE (140). Probability density function of cohesion and angle of friction for the slopes were developed using limit equilibrium methods. These shear strengths were then used to determine the probability density function of safety factor and reliability index using the probabilistic methods. Results of the probabilistic analysis indicate that with ascending values of the uncertainties the reliability index decreases. Furthermore, it was determined that with the Monte Carlo simulation the seed number used has little effect on the reliability index of the safety factor especially with seed numbers in excess of 1200. Variations in the overall reliability index of safety factor were observed between the two slopes and this difference is explained by the differences in complexities of the geology within the cross-section.

Minimizing the expected total cost of a structure, including maintenance and construction is a difficult problem because of the presence in the objective function of the yearly failure rates, which have to be calculated by an optimization... more

Minimizing the expected total cost of a structure, including maintenance and construction is a difficult problem because of the presence in the objective function of the yearly failure rates, which have to be calculated by an optimization problem per each failure mode. In this paper, a new method for the design of structures that minimizes the total expected costs of the structure during its lifetime based on Benders’ decomposition is presented. In addition, some tools for sensitivity analysis are introduced, which make it possible to determine how the cost and yearly failure rates of the optimal solution are affected by small changes in the input data values. The proposed method is illustrated by its application to the design of a composite breakwater under breaking and non-breaking wave conditions.

L’Ordine degli Ingegneri della Provincia di Cagliari in collaborazione con il Dipartimento di Ingegneria Civile, Ambientale ed Architettura dell’Università degli studi di Cagliari. presenta il seminario di approfondimento: “Effetti... more

L’Ordine degli Ingegneri della Provincia di Cagliari
in collaborazione con il
Dipartimento di Ingegneria Civile, Ambientale ed
Architettura dell’Università degli studi di Cagliari.
presenta il seminario di approfondimento:
“Effetti dell’incendio sulle strutture:
indagini ed interventi di consolidamento”
Mercoledì 23 marzo 2016 ore 15.00 - 19.30
Aula Magna Facoltà di Ingegneria
Via Marengo 2 – Cagliari
Dott. Ing. Fausto Mistretta, Università degli Studi di Cagliari
Dott. Ing. Massimo Deplano, Min. Interno, Dip. VV.F. Comando Prov. Cagliari
Prof. Ing. Franco Bontempi, Università di Roma La Sapienza
Dott. Ing. Flavio Stochino, Università degli Studi di Sassari
Dott. Ing. Paola Meloni, Università degli Studi di Cagliari
Dott. Ing. Giuseppina Vacca, Università degli Studi di Cagliari

Abstract In this paper the solution of the problem of a single-degree-of-freedom (sdof) oscillator with a unilateral barrier under the action of a Gaussian non-stationary white noise is considered. The joint probability density function... more

Abstract In this paper the solution of the problem of a single-degree-of-freedom (sdof) oscillator with a unilateral barrier under the action of a Gaussian non-stationary white noise is considered. The joint probability density function of displacement and velocity is sought by trying approximate solutions to the Fokker-Planck-Kolmogorov equation. The solution is forced to fit a bivariate Gaussian distribution and the results are compared with an extended numerical analysis of the free and forced oscillations of a sample sdof system. Finally, the procedure is fully discussed and lines for further research are set forth.

Extreme loads can have devastating effects on civilian structures since these buildings are not designed to have to withstand extreme events. Typical buildings and other critical infrastructure are particularly prone to external man-made... more

Extreme loads can have devastating effects on civilian structures since these buildings are not designed to have to withstand extreme events. Typical buildings and other critical infrastructure are particularly prone to external man-made attacks. This study focuses on probabilistic analyses, and investigates the probability of failure of a precast concrete wall subjected to blast loads. The wall under investigation is a non-load bearing precast concrete panel used as exterior cladding for buildings. From the blast design point of view, these walls must protect people and equipment from external detonations. The aim of the paper is to compute both the fragility curves of typical precast concrete cladding subjected to blast loads, and the failure probability of the cladding, considering a detonation of a vehicle borne improvised explosive device (VBIED). To this aim non-linear dynamic analyses are carried out by the widely adopted equivalent non-linear SDOF method for the precast concrete panel. The fragility curves and the failure probability of the precast concrete cladding wall are computed using Monte Carlo simulations.

Este artículo expone la necesidad de adelantar la revisión de los factores parciales, así como de los valores de velocidad de diseño para lascargas de vientoprovistos por la NSR-10. Empleando métodos de confiabilidad y la información... more

Este artículo expone la necesidad de adelantar la revisión de los factores parciales, así como de los valores de velocidad de diseño para lascargas de vientoprovistos por la NSR-10. Empleando métodos de confiabilidad y la información disponible sobre la velocidad del viento en Colombia se demuestra que los diseños que se obtienen al emplear los factores parciales y el mapa de amenaza eólica prescritos porla NSR-10 carecen de uniformidad en su nivel de seguridad (índice de confiabilidad). También se prueba que no es posible determinar un factor parcial para la carga de viento que al ser usado junto con el mapa eólico de la normativa actual garantice uniformidad en la seguridad de las estructuras. Además de esto, se exponen argumentos técnicos y socieconómicos a favor de una revisión conjunta de las velocidades y factores parciales que considere las características eólicas y la realidad colombiana y que conduzca al reajuste de estos valores.

ABSTRACT Predictive models are essential in dam safety assessment. Both deterministic and statistical models applied in the day-to-day practice have demonstrated to be useful, although they show relevant limitations at the same time. On... more

ABSTRACT Predictive models are essential in dam safety assessment. Both deterministic and statistical models applied in the day-to-day practice have demonstrated to be useful, although they show relevant limitations at the same time. On another note, powerful learning algorithms have been developed in the field of machine learning (ML), which have been applied to solve practical problems. The work aims at testing the prediction capability of some state-of-the-art algorithms to model dam behaviour, in terms of displacements and leakage. Models based on random forests (RF), boosted regression trees (BRT), neural networks (NN), support vector machines (SVM) and multivariate adaptive regression splines (MARS) are fitted to predict 14 target variables. Prediction accuracy is compared with the conventional statistical model, which shows poorer performance on average. BRT models stand out as the most accurate overall, followed by NN and RF. It was also verified that the model fit can be improved by removing the records of the first years of dam functioning from the training set.

This paper represents an ex post rethinking of the contribution of artificial intelligence techniques to safety management, based on a long work experience in applying artificial intelligence to several engineering fields, from dam safety... more

This paper represents an ex post rethinking of the contribution of artificial intelligence techniques to safety management, based on a long work experience in applying artificial intelligence to several engineering fields, from dam safety to environmental protection, from seismic monitoring to the protection of cultural heritage. The main issue is that developing models for assessing safety is a hard task, but integrating partial models may provide good results. Even if each single model is poor, a sort of epiphenomenal intelligence emerges from the behaviour of a system made of small partial models and users perceive it as a reliable assistant.
Keywords: artificial intelligence, safety management, epiphenomenal intelligence, monitoring, ethnography, anthropology, expert systems, decision support sustems, sicurezza strutturale, sistemi di supporto alle decisioni, sistemi eperti, intelligenza artificiale, dighe, frane

This paper provides a presentation of phimeca software for reliability analysis. The completion of this software has been achieved thanks to years of experience at the French Institute for Advanced Mechanics and phimeca engineering... more

This paper provides a presentation of phimeca software for reliability analysis. The completion of this software has been achieved thanks to years of experience at the French Institute for Advanced Mechanics and phimeca engineering company is developing the commercial version. First, inherent hypotheses of first/second order and conditional simulation methods are briefly stated and their implementation discussed. Algorithms combining the physical model under concern – defined through an explicit formula, a finite element code computation or a user-defined function – and a stochastic model of the input are then presented to the reader. A special attention is given to the graphical user interface GUI in this paper so as to comply with the objectives of this special issue of “Structural Reliability Software” and the use of the GUI is illustrated through a very basic example. To conclude, a significant industrial application is presented demonstrating the capabilities of the software in the context of a large finite element model and a non-linear material behaviour.

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result,... more

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today's structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk...

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result,... more

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today’s structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk analysis of the disproportionate collapse. As a result, implementing design for robustness is still very much a grey area and more so when it comes to defining means to quantify robustness. This paper revisits the most common robustness frameworks, highlighting their merits and limitations, and identifies one among them which is very promising as a way forward to solve the still open challenges.