Egidijus Rytas Vaidogas

Sustainable development and major industrial accidents: The beneficial role of risk‐oriented structural engineering

Abstract Sustainable development can be restricted by major accidents which occur in hazardous industries. Almost every major accident may have negative influence on each of the three constituents of the sustainable development: social, environmental and economic part. A characteristic feature of the most of major accidents is severe damage to the structural systems built inside and outside of the industrial facility in which the accident happens. To avoid such accidents or at least to reduce their consequences, structural systems should be designed using a risk‐based approach. On the level of detailed structural design, a formal measure of risk should be introduced and applied to express the effectiveness of the structural solution in terms of accident mitigation and minimization of potential consequences. The structural design should involve the consideration of possible accident scenarios and positive or negative contribution of structures and structural failures to the escalation or de‐escalation of t...

Solving Civil Engineering Problems by Means of Fuzzy and Stochastic MCDM Methods: Current State and Future Research

The present review examines decision-making methods developed for dealing with uncertainties and applied to solve problems of civil engineering. Several methodological difficulties emerging from uncertainty quantification in decision-making are identified. The review is focused on formal methods of multiple criteria decision-making (MCDM). Handling of uncertainty by means of fuzzy logic and probabilistic modelling is analysed in light of MCDM. A sensitivity analysis of MCDM problems with uncertainties is discussed. An application of stochastic MCDM methods to a design of safety critical objects of civil engineering is considered. Prospects of using MCDM under uncertainty in developing areas of civil engineering are discussed in brief. These areas are design of sustainable and energy efficient buildings, building information modelling, and assurance of security and safety of built property. It is stated that before long the decision-making in civil engineering may face several methodological problems: the need to combine fuzzy and probabilistic representations of uncertainties in one decision-making matrix, the necessity to extend a global sensitivity analysis to all input elements of a MCDM problem with uncertainties, and an application of MCDM methods in the areas of civil engineering where decision-making under uncertainty is presently not common.

Assessment of structures subjected to accidental actions using crisp and uncertain fragility functions

Abstract An application of fragility functions to the assessment of potential damage due to an accidental action is analysed. The assessment is carried out as an estimation of the probability of a foreseeable damage event (damage probability). This probability is expressed as a mean value of a fragility function developed for the damage event under study. A Bayesian prior (posterior) distribution specified for this mean value is used as an estimate of the damage probability. The prior distribution is derived by transforming prior knowledge through the fragility function and “mapping” this knowledge on the scale of probability values. The technique of Bayesian bootstrap resampling is applied to update the prior distribution. The new information used for the updating consists of a relatively small number of experimental observations of the accidental action. To facilitate the updating, these observations are transformed into a fictitious statistical sample of fragility function values. The updating is first...

Reliability measures in multicriteria decision making as applied to engineering projects

This paper contains two examples of a combined application of MultiCriteria Decision Making (MCDM) and reliability analysis. The examples illustrate a theoretical discussion presented by the first two authors in the same issue of the journal. The first example is concerned with a comparative planning and arranging of building construction process. The second one has to do with comparison between alternative designs of a floor structure. Reliability of alternative construction plans and failure probabilities of alternative arrangements of the floor structure are taken as attributes used to MCDM. Various normalisation methods and decision-making criteria are applied to solving problems considered in the examples. It is demonstrated that reliability measures used to MCDM can create interdependence between attributes of the alternatives under comparison. Introducing reliability measures into decision making generates the need to replace traditionally deterministic attributes with characteristics of random quantities such as mean values. It is concluded that introducing reliability measures into MCDM problems requires an effort mainly at a formulation of these problems.

Introducing reliability measures into multi-criteria decision-making

This paper addresses comparing Alternative Designs (ADs) of an engineering project by taking into account fail-safe behaviour of these designs. The methodology of Multi-Criteria Decision-Making (MCDM) is suggested for the selection of the optimal design among available ones. The prime objective of this paper is introducing reliability and availability into the mathematical framework of MCDM. The discussion also covers applying basic elements of Reliability-Based Optimisation (RBO) and utility theory in solving problems of MCDM. The main message is that the mathematical framework of MCDM is sufficiently flexible to adopt probabilistic attributes (characteristics) of ADs. The paper considers intersections of MCDM with methods of reliability theory. Examples of a combined application of MCDM and reliability theory are presented by both the authors together with a third co-author in a paper given in the same issue of the journal.

Explosive damage to industrial buildings: Assessment by resampling limited experimental data on blast loading

Abstract Assessment of damage to industrial buildings due to accidental explosions in air is considered. It is suggested to formulate the result of the damage assessment in the form of risk. The expression of risk embraces probabilities of foreseeable damage events (damage probabilities) and outcomes (consequences) of suffering these events. The situation is examined when blast loading imposed by an accidental explosion is predicted by a series of experiments. They yield a small‐size sample of blast loading characteristics. It is suggested to idealise the formation of explosive damage to industrial buildings by means of event trees diagrams. A quantitative analysis of these diagrams can be carried out by developing fragility functions for their branching points. Each branching point is used to represent a structural failure contributing to the final explosive damage. The fragility functions are applied to expressing the conditional probabilities of explosive damage. With these probabilities, a technique o...

Decision Making Methods and Applications in Civil Engineering

1Department of Construction Technology and Management, Faculty of Civil Engineering, Vilnius Gediminas Technical University, Saulėtekio Alėja 11, LT-10223 Vilnius, Lithuania 2Department of Structural Mechanics, Faculty of Civil Engineering, Brno University of Technology, Veveři Street 95, 602 00 Brno, Czech Republic 3Department of Structural Engineering, Faculty of Engineering, Cairo University, Giza 12613, Egypt 4Department of Labour Safety and Fire Protection, Faculty of Civil Engineering, Vilnius Gediminas Technical University, Saulėtekio Alėja 11, LT-10223 Vilnius, Lithuania

Simulation-based predicting the position of road tank explosions. Part I: data and models

Road tankers used for the transportation of flammable liquids and liquefied gases can be involved in accidents which escalate into fires and the so-called boiling liquid expanding vapour explosions. The damaging effects of these phenomena on roadside property depend on the position and orientation of exploding tanks in relation to vulnerable roadside objects. This study presents a simulation-based approach to the prediction of the position of road tank explosions. The position is expressed by longitudinal and transverse rest position of an exploding tank as well as departure angle of the tank. As a part of this study, data on transverse rest position and departure angle was collected and used to fit probability distributions which express uncertainties in these circumstantial characteristics of road tank accidents. It was found that data on the longitudinal rest position is difficult to obtain and modelling this accident characteristic will have to rely on a subjective specification of probability distributions. Such distributions can be chosen by applying approaches used in the field of quantitative risk assessment. Probability distributions, partly subjective and partly based on hard data, are applied to simulate values of potential explosion coordinates. The simulation results have the premise to be applied to forecasting mechanical and thermal effects of explosions on road and assessing damage from them. A case study used to evaluate the performance of the models proposed in this study is presented in the second part of the paper.

Actions imposed on structures during man‐made accidents: Prediction via simulation‐based uncertainty propagation

Abstract Prediction of mechanical, thermal, and chemical actions induced during man‐made accidents (accidental actions) is of crucial importance to assessing potential damage to structures exposed to these actions. A logical result of such a prediction may be expressed in the form of probabilistic models describing likelihood of occurrence and characteristics of accidental actions. For many types of accidental actions the models are to be selected under the conditions of incomplete knowledge about and/or scarce statistical information on intensities and likelihood of imposition of the actions. This paper proposes a simulation‐based procedure intended for a selection of the probabilistic models under these conditions. The proposed procedure is formulated in the context of the classical Bayesian approach to risk assessment. The main idea of it is that statistical samples necessary for fitting the probabilistic action models can be acquired from a stochastic simulation of accident sequences leading to an imp...

Pressure vessel explosions inside buildings: Assessing damage using stochastic accident simulation : Structures subjected to extreme natural and man-made hazards

A methodological framework of assessing damage to buildings caused by accidental pressure vessel explosions is presented. It is proposed to assess the damage using a stochastic simulation of actions imposed by these explosions. The stochastic simulation is used as a tool, which allows the considerable uncertainties related to explosion accidents to be dealt with efficiently. A methodology developed in the field of quantitative risk assessment and known as the predictive, epistemic approach to risk analysis is proposed to deal with these uncertainties and to deal with the scarcity of data related to specific situations of structural exposure to a potential pressure vessel explosion. It is also proposed to provide the final result of the simulation-based damage assessment. This will be shown as a set of pairs of foreseeable damage events and subjective probabilities of their occurrence. These probabilities are measures of uncertainty related to the damage events. The uncertainty is considered to be purely epistemic, that is, resulting from the lack of knowledge only.