Simulation‐based forecasting effects of an accidental explosion on the road. Part II: Case study

The paper contains a case study covering forecasting mechanical effects of an explosion which can be generated during a road accident. It illustrates a practical application of the simulation‐based procedure developed for such forecasting in the first part of the paper. The case study reveals the amount and character of the knowledge necessary to carry out this forecasting. Its final result is a probabilistic model describing likelihood of occurrence of accidental explosion as well as characteristics of the incident blast wave generated by this explosion. The accident simulation is based on the classical Bayesian approach to risk assessment. The case study described in the paper shows how to formulate the initial knowledge in line with this approach. Particular attention has been given to handling subjective information (expert opinions) within the problem under analysis. It is shown that this information is indispensable for dealing with the sparseness of hard experience data on most of the phenomena leading to an accidental explosion. The stochastic simulation demonstrated in the paper serves the purpose of propagating uncertainties related to these phenomena. The probabilistic action model describing the potential explosion takes account of these uncertainties. First Published Online: 27 Oct 201

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.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

Probabilistic framework for assessing risks to structures stemming from accidental explosions

In the paper, an attempt is made to formulate a probabilistic framework for an assessment of risk to structures resulting from accidental vapour cloud explosions (VCEs). This framework is based on the general methodology known in the quantitative risk analysis as the classical Bayesian approach to risk assessment. Attention is centred on the estimation of the annual probabilities of potential damages to structural systems exposed to dangers of VCEs. The paper sets up the mathematical problem of assessing risk to structures related to VCEs and, for the most part, contains discussion on the methodological tasks to be solved in this assessment. Frist Published Online: 30 Jul 201

A look at data situation in probabilistic risk analysis as applied to structural systems/Duomenų situacija tikimybinėje rizikos analizėje, taikant ją konstrukcinėms sistemoms

Straipsnyje aptariamas duomenų poreikis ir sukaupti duomenys, kurių reikia, norint integruoti tikimybinę rizikos analizę su tikimybiniu konstrukcinių sistemų (pastatų, statinių, tiesinių) skaišiavimu. Pagrindinis dėmesys skirtas duomenims apie avarijas įvairiuose pramoniniuose objektuose ir statybinių konstrukcijų avarijas. Pramoninių objektų konstrukcinės sistemos gali būti pažeistos dėl pavojingų gamtinių reiškinių ar žmogaus veiklos padarinių. Nuostoliai, sukelti šių veiksnių, gali būti vertinami kaip eksploatacinės išlaidos arba juos atlygina draudikas. Draudimo problema yra lengvai išsprendžiama, jeigu draudikai turi pakankamai duomenų apie anksčiau patirtų nuostolių dydį ir dažnį. Tačiau sunkios avarijos pramoniniuose pastatuose įvyksta retai ir duomenų apie patirtus nuostolius būna sukaupta mažai. Tokiu atveju riziką, t. y. nuostolius ir jų patyrimo dažnį galima prognozuoti tikimybinės rizikos analizės metodais. Matematiniams tikimybinės rizikos analizės metodams taikyti reikia turėti statistinių duomenų. Šie duomenys turi atspindėti pramoniniuose objektuose įrengtų techninių sistemų patikimumą ir parengtą. Kita svarbi duomenų rūšis yra informacija apie avarijas, įvykusias įvairiuose pramoniniuose objektuose. Šie duomenys yra būtini, įtraukiant į tikimybinę rizikos analizę galimus konstrukcinių sistemų atsakus. Avarijų ar stichinių nelaimių metu konstrukcinės sistemos būna veikiamos tokių apkrovų, kurios nenumatomos projektuojant šias sistemas. Avarijų duomenys kaupiami įvairiai. Didžiausi duomenų rinkiniai yra duomenų bankai. Straipsnyje trumpai apibūdinti žinomiausi duomenų bankai, sukurti Vakarų Europos šalyse ir dažnai aprėpiantys visame pasaulyje įvykstančias avarijas. Pavieniai bankai detaliai nenagrinėjami. Straipsnyje analizuotos sukauptų duomenų prieinamumo bei tinkamumo vertinant konstrukcinių sistemų patikimumą problemos. Kitas svarbus duomenų šaltinis yra informacija apie konstrukcijų avarijas. Straipsnyje trumpai aptariami specialiojoje literatūroje paskelbti duomenys apie statybinių konstrukcijų avarijas ir šie duomenys vertinami tikimybinės rizikos analizės aspektu. Nustatyta, kad bendro pobūdžio statybinių konstrukcijų avarijų apžvalgos yra mažai naudingos tikimybinei rizikos analizei. Tose apžvalgose daugiausia nagrinėjamos avarijų priežastys, o ne pasekmės, avarijų aplinkybės detaliai neaprašomos. Rizikos analizei naudingesnės yra specialiųjų konstrukcinių sistemų, pavyzdžiui, didelių užtvankų, avarijų apžvalgos. Jose pateikiama informacija yra daug detalesnė ir aprėpia ne tik konstrukcinio pobūdžio įvykius, bet ir, pavyzdžiui, nuostolius, patiriamus įvykus avarijoms. First Published Online: 26 Jul 201

Actions imposed on structures during manâ€made accidents: Prediction via simulationâ€based uncertainty propagation

Prediction of mechanical, thermal, and chemical actions induced during manâ€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 simulationâ€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 imposition of accidental actions. Formally, the stochastic simulation of accidents serves the purpose of propagating uncertainties related to the physical phenomena capable of inducing accidental actions. These uncertainties are quantified in line with the classical Bayesian approach. The simulationâ€based procedure can be used for damage assessment and risk studies within the methodological framework provided by the aboveâ€mentioned approach. Apkrovos, veikianÄios konstrukcijas technogeninių avarijų metu: prognozavimas neapibrėžtumus modeliuojant stochastinio modeliavimo bÅ«du Santrauka Mechaniniai, terminiai ir cheminiai poveikiai, pasireiÅ¡kiantys sunkių technogeninių avarijų metu (avariniai poveikiai), gali sukelti didelius statybinių konstrukcijų pažeidimus ir griÅ«tis. Prognozuoti Å¡iuos poveikius yra svarbu norint tų pažeidimu ir griÅ«Äių ir iÅ¡vengti. LogiÅ¡kas tokio prognozavimo rezultatas yra tikimybiniai matematiniai modeliai, nusakantys avarinių poveikių pasireiÅ¡kimo tikÄ—tinumÄ… ir charakteristikas. Daugeliu atvejų tokius modelius reikia parinkti stokojant informacijos apie poveikius, sukelianÄius fizinius reiÅ¡kinius. SiÅ«loma stochastinio modeliavimo procedÅ«ra, kuri turÄ—tų palengvinti avarinio poveikio matematinio modelio parinkimÄ… ribotos informacijos sÄ…lygomis. Å i procedÅ«ra sukurta laikantis klasikinio BÄ—jeso požiÅ«rio į rizikos analizÄ™ principų. PagrindinÄ— straipsnio idÄ—ja yra ta, kad statistinÄ—s imtys, bÅ«tinos poveikių modeliams parinkti, gali bÅ«ti generuotos atliekant stochastinį avarijos modeliavimÄ…. SiÅ«loma stochastinio modeliavimo procedÅ«ra gali bÅ«ti taikoma vertinant potencialius konstrukcijų pažeidimus avariniais poveikiais ir atliekant rizikos analizÄ™, grindžiamÄ… klasikinio BÄ—jeso požiÅ«rio principais. ReikÅ¡miniai žodžiai: technogeninÄ— avarija, avarinÄ— apkrova, rizikos vertinimas, neapibrėžtumas, BÄ—jeso požiÅ«ris, stochastinis modeliavimas First Published Online: 14 Oct 201

Risk Oriented Design of Protective Highway Structures

The problem of risk-based design of protective highway structures is considered. It is stated that the accidents involving damage to components of road infrastructure are a natural subject of a quantitative risk analysis. The paper discusses how to apply a risk oriented approach to the design of protective components of road infrastructure. A simulation- based procedure developed for a design of a protective highway structure by means of a multi-attribute selection is suggested. Attention is focused on uncertainties related to both accidental actions, which must be sustained by the protective structure, and behaviour of the structure under these actions. The proposed procedure serves for a comparison of alternative designs of the protective structure. The comparison takes into account epistemic uncertainties in failure-to-protect probabilities related to the alternative designs. It is shown that the multi-attribute selection can be carried out as a simulation- based propagation of the epistemic uncertainties. A loop of such simulation must involve deterministic algorithm of the multi-attribute selection. Repeating this loop a number of times yields relative frequencies of selecting individual alternative designs as the best ones. The optimal alternative design can be chosen as a design with the largest frequency of selection

Accidental explosions on the railway: Simulationâ€based prediction of damage to nearby buildings

A procedure for estimating potential damage to buildings induced by accidental explosions on the railway is developed. By the damage failures of nearby structures due to actions generated by the accidental explosions are meant. This damage is measured in terms of probabilities of potential failures caused by explosions. The estimation of the damage probabilities is based on stochastic simulation of railway accidents involving an explosion. The proposed simulationâ€based procedure quantifies epistemic (stateâ€ofâ€knowledge) uncertainties in the damage probabilities. These uncertainties are expressed in terms of Bayesian prior and posterior distributions. The foundation of the procedure is a computer intensive method known as the Bayesian bootstrap. It is used for approximating the posterior distributions of damage probabilities. The application of the Bayesian bootstrap makes the proposed procedure highly automatic and convenient for assessing structures subjected to the hazard of the accidental actions. In addition, it can be used for specifying safe distances between the railway and nearby buildings. Structures of these buildings can be designed for tolerable probabilities of failures induced by accidental explosions. First Published Online: 27 Oct 201

Simulation-based forecasting effects of an accidental explosion on the road. Part I: Methodological framework

Forecasting mechanical actions induced by accidental explosions on the road is of crucial importance to assessing potential damage to structures and non-structural property exposed to them. A logical result of such forecasting may be expressed in the form of probabilistic models. They should quantify likelihood of occurrence and physical characteristics of accidental explosions. Generally the models are to be selected under the conditions of sparse statistical information on intensities and likelihood of explosive actions. The first part of the present paper proposes a simulation-based procedure intended for selection of the probabilistic models in the absence of direct statistical data on the explosive actions. The proposed procedure is formulated in the context of the classical Bayesian approach to risk assessment. The main idea of the procedure is that statistical samples necessary for fitting the probabilistic models can be acquired from a stochastic simulation of an accident involving an explosion on the road. The proposed simulation-based procedure can be used for damage assessment and risk studies within the methodological framework provided by the above-mentioned approach. A case study illustrating an application of the proposed procedure is given in the second part of the paper

A simulation approach to reliability assessment of plastic frames/Vienas plastinių rėmų patikimumo verti nimo stochastiniu modeliavimu būdas

Straipsnyje nagrinėjamas plastinių rėmų patikimumo vertinimas stochastinio modeliavimo metodu, kuris vadinamas radialiniu ėmimu. Patikimumo problema yra formuluojama apkrovų erdvėje. Naudojamas faktas, kad daugeliui praktinių problemų apkrovų erdvės dimensija yra gerokai mažesnė už bazinių kintamųjų erdvės dimensiją. Plastinės avarijos tikimybė vertinama naudojantis proporcingo apkrovos didinimo metodu. Atsisakoma apkrovų erdvės diskretizavimo pagal apkrovų proporcijas. Deterministiniu rėmų mechaniniu modeliu parinktas statinės formuluotės uždavinys, turintis tiesinio programavimo uždavinio formą. Plastinės avarijos vertinimui naudojama radialinio ėmimo ir tiesinio programavimo uždavinio kombinacija. Jungiamoji grandis tarp radialinio ėmimo ir mechaninio modelio yra apkrovos krypčių ir pasiskirstymo vektorius, kuris išreiškiamas kaip krypties kosinusų vektorius. Išspręsti dviejų rėmų pavyzdžiai. Gauti rezultatai lyginami su kitų autorių rezultatais. First Published Online: 26 Jul 201