Non-parametric structural reliability analysis using random fields and robustness evaluation (original) (raw)
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Comparative study of computational methods of structural reliability assessment
Safety is an essential requirement of a structural system. Reliability is an additional tool of growing importance in engineering, as it allows us to quantify uncertainties in the design. Thus, reliability assists us in making more suitable decisions regarding the safety of a structure. The present work compares and analyzes structural reliability methods applied to various examples of limit state functions. These methods are essential tools for this analysis because they identify and quantify uncertainties in random variables, allowing the evaluation of the probability of failure of the structure. Structural reliability methods were programmed and simulated in the Python language. The performance of these methods was analyzed through examples of linear, nonlinear, implicit, and explicit limit state functions. The results indicate that the simulation of Monte de Carlo brute force (MCBF) and importance sampling (MCAI) proved to be quite efficient for the examples studied in this work, with values equal to or very close to the reference values from the literature. The First Order and Second Moment Method (FOSM) presented limitations in some examples when the basic random variables do not have a normal distribution and the limit state function is nonlinear. The first-order reliability method (FORM) employs a failure surface linearization, which does not work well for highly nonlinear problems. The second-order reliability method (SORM) has improved the FORM results by including additional information about the curvature of the limit state function.
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Author of the monograph, Juraj Králik, has been working at the Department of Structural Mechanics as assistant since September 1, 1976 and as associate professor since January 18, 1988. During the years 2000 - 2006 he was the head of Department. He holds lectures in two study programs: Engineering Structures and Transport Structures; and Civil Engineering and Architecture. He teaches the following subjects: Mechanics of Structures and Materials, Seismic Enginering and Computer Design, Risk Engineering, Safety and Reliability of Buildings. His regular students and doctoral students have won several prizes in the student research competitions at the Faculty. He has been implementing advanced computer programs and methods in teaching and research at the Department, being himself an author of more than 100 programs of the static and dynamic applications. He is guarantor of using the licensed software systems ANSYS and MathCAD at the Department and Faculty, too. As the co-guarantor, he has established the doctoral study program “Applied Mechanics”. During the years 2000-2006, in cooperation with the Slovak Chamber of the Civil Engineers he was the supervisor of seven volumes of the postgraduate study course „Aeroelasticity and Seismicity“, and the chairman of seven volumes of the International Conference „New Trends in the Statics and Dynamics of Buildings“. His results were presented in more than 300 papers in conference proceedings and journals, 10 papers are indexed in prestigious database „Web of Science“. Three papers were published in the currented international journals „Mathematics and Computers in Simulation” (1999), „Control and Cybernetics” (2006) and “Engineering Structures” (2009). 17 research and grant projects were managed by him. His works were cited in more than 200 papers in scientific and special publications. As the reputable scientific personality he was the member of the scientific committees of several international conferences abroad. In the year 1989 he was appointed an expert of the safety and reliability of nuclear power plants in Slovakia. He cooperated at the analysis of the seismic resistance of the nuclear power plant buildings and their safety under impact of explosion, missile and container drop. More than 100 expertises were realized by him in the field of the safety and reliability of the NPP buildings in Slovakia. Some of his research and expert works were awarded by significant institutions. The most significant is the honorable award of the Czech Engineering Academy for the paper „Probability Analysis of Reinforced Concrete Structure Failure of Nuclear Power Plants Due to Loss of Coolant Accident “ published in the journal „ENGINEERING MECHANICS“ in 2006.
A method for the reliability analysis of structural systems of medium complexity is proposed. The aim is to reduce the necessary computing effort for an accurate evaluation of the failure probabilities of the structure and its elements. This is achieved through domain decomposition (partitioning) of the probabilistic space and subsequent biased sampling in the areas close to the fail-safe surface. The results from the proposed algorithm are compared with those obtained from Monte Carlo simulation and the performance of the method is examined. In particular, the reliability of "optimal" deterministic designs based on the provisions of Eurocodes is investigated. Moreover, the robustness and computing efficiency of the method is examined for a non-linear limit state function and a 31-bar truss. Two parametric studies are performed with respect to the parameters of the method and the effects of indeterminacy on the reliability index of the structure are outlined.
Uncertainty Modeling: Fundamental Concepts and Models
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International Journal of Innovation and Applied Studies, 2017
We know that with the reliability structure, modeling is based on a deterministic physical system: the latter extract degradation mechanisms. Thus, mechanisms taken into account are crack propagations and are defects from thermal or vibratory fatigue, corrosion or erosion etc... The structure is submitted to some loadings in its environment; this, defines a finite number of modes of degradation. We can envision envisage two possible outcomes: failure or success. Therefore, we could consider the failure probability deterministic or probabilistic. According to the probabilistic approach, the risk will be evaluated without probability of failure. It is understood that this evaluation represents the entire problem of this work. In our study, we are going to be examining the development of two methods of structural reliability, which are the first order and second order: That is why we are going to use FORM and SORM method alongside with the Monte Carlo simulation, which are so effective...
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