Protecting built property against fire disasters: Multi ‐attribute decision making with respect to fire risk

The protection of buildings against fire disasters may require a comparison of alternative fire safety designs. The fire safety solutions can be compared by means of a general methodology known as multi‐attribute selection or multi‐criteria decision making. The alternative fire designs can be described by a number of attributes which characterise each of the alternatives. Fire risk expressed in the general form used for the quantitative risk assessment is applied to compose the set of attributes of a multi‐attribute selection problem. It is shown how to accomplish the multi‐attribute selection in the presence of epistemic uncertainties in the elements of fire risk estimate. Epistemic probability distributions assigned to elements of fire risk are specified and propagated though models of the multi‐attribute selection by means of Monte Carlo simulation. An example presented in the paper considers the choice among alternative systems of automatic fire sprinklers. Santruka Norint užtikrinti pastatu gaisrine sauga, gali prireikti lyginti alternatyvius projektinius saugos sprendimus. Tai atlikti galima pasitelkiant daugiakriterinio vertinimo metodologija. Alternatyvieji sprendimai gali būti aprašyti keletu charakteristiku (atributu) ir lyginami vienas su kitu. Straipsnyje atributu sarašas sudaromas naudojant gaisro rizikos išraiška, sudaroma kiekybinio rizikos vertinimo principais. Parodyta, kaip atlikti daugiakriterini vertinima, kai rizikos išraiškos elementai yra neapibrežti epistemine prasme. Episteminio neapibrežtumo skirstiniai priskiriami uždavinio atributams ir propaguojami matematiniais daugiakriterinio vertinimo modeliais pasitelkiant Monte Karlo modeliavima. Pateikiamas pavyzdys, nagrinejantis automatiniu sprinkleriu sistemos parinkima iš keliu alternatyviu variantu. First Published Online: 10 Feb 201

The risk to structures built near roads and rails used for moving hazardous materials

An assessment of parts of transportation infrastructure in terms of hazards to roadside territory is considered. It is suggested to assess individual segments of road and railway network by estimating risks posed by potential fires and explosions on road and rail. Boiling liquid expanding vapour explosion of tanker trucks and tank cars is identified as the most hazardous and likely high consequence accident in the land transport. It is proposed to express the risk to built roadside objects by means of an annual damage frequency. This frequency is considered to be a specific physical characteristic of the road or railway segment under analysis. It is shown that estimating the damage frequency requires assessing effects of a potential explosion on road or rail and developing a fragility function for the roadside object ana­lysed as a potential target. An example case study is presented. It considers a potential thermal damage to a reservoir (stationary tank) built in the vicinity of a highway. The damage can be caused by an explosion of a propane tanker truck. Results of the risk assessment are expressed in terms of probabilities of specific damage events

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

Pengaruh Metode Pengajaran Eksperimen Terhadap Motivasi Belajar Siswa Pada Mata Pelajaran Ilmu Pengetahuan Alam

Ilmu pengetahuan alam (IPA) menurut Muwarni (1999), adalah ilmu yang mempelajari aspek-aspek realitas alamiah yang dapat diamati secara fenomenologis, dibuktikan secara empiris, dan dapat dihitung atau diprediksikan sebab dan akibatnya. IPA merupakan basic dari ilmu pengetahuan empiris yang bermanfaat dalam kehidupan sehari-hari terutama dalam dunia kerja dimasa-masa mendatang, maka sangat penting bagi siswa untuk lebih memahami dan menguasai mata pelajaran IPA, terutama melalui model aplikasi atau eksperimen

Modelling uncertainties in assessing risks to structures caused by accidental explosions/Neapibrėžtumų modeliavimas vertinant avarinių sprogimų riziką pastatams

Siūloma procedūra avarinių sprogimų mechaninių poveikių neapibrėžtumams kiekybiškai įvertinti. Nagrinėjamas pavojingasis reiškinys yra dėl avarinių dujų nuotėkių susidarančių degių ir sprogių debesų detonacija ir jos sukeliama sprogimo banga. Sprogimų poveikių intensyvumai yra apibūdinami tikimybinei rizikos analizei įprastomis pavojaus funkcijomis (angl. hazard functions). Galutinis siūlomosios procedūros taikymo rezultatas yra pavojaus funkcijų parinkimas statistinių imčių, sukurtų stochastinio modeliavimo būdu, pagrindu. Taikomas Monte Karlo metodas, o modeliuojami nepalankieji reiškiniai, kurių eskalacija baigiasi dujų ir oro misinio debesies detonacija. Siūlomos procedūros taikymo rezultatai leidžia įvertinti dinamines apkrovas, galinčias veikti tiriamą (vertinamą konstrukcinę sistemą įvykus aptariamo tipo sprogimui. Teoriu požiūriu siūloma procedūra remiasi tikimybinės rizikos analizės metodologija, kuri vadinama klasikiniu Bėjeso požiūriu (angl. classical Bayesian approach). Teigiama, kad sprendžiant nagrinėjamą problemą yra sunku išsiversti be Bėjeso požiūrio, nes pavojaus funkcijas tenka parinkti labai ribotos statistinės informacijos sąlygomis. Taikant procedūrą operuojama stochastiniais (angl. aleatory) ir pažintiniais (angl. epistemic) neapibrėžtumais. Skaiciuojant pagal procedūros algoritmą neapibrėžtumai, susiję su sprogimų pavojaus funkcijomis, yra išreiškiami per ,žemesnio" lygio neapibrėžtumus, apibūdinančius tuos reikškinius, kurių eskalacija gali baigtis sprogimu. Pastebėta, kad šiems neapibrėžtumams kokybiškai išreiksti turima daug daugiau statistinės informacijos, nei neapibrėžtumams, tiesiogiai susijusiems su mechaniniais sprogimo bangos poveikiais konkreciai konstrukcinei sistemai. Numatoma praktinio procedūros taikymo sritis yra pavojingųjų dujų ūkio objektų rizikos analizė. Procedūra leidžia įvertinti tų objektų pavojingumą vertinamai (projektuojamai) konstrukcinei sistemai. First Published Online: 30 Jul 201

Bayesian approach to forecasting damage to buildings from accidental explosions on railway

A procedure for estimating potential damage to buildings induced by accidental explosions on railway is developed. By the damage are meant failures of nearby structures due to actions generated by the accidental explosions. This damage is measured in terms of probabilities of potential failures caused by the explosions. The estimation of the damage probabilities is based on a stochastic simulation of railway accident involving an explosion. The proposed simulation-based procedure quantifies epistemic (state-of-knowledge) uncertainties in the damage probabilities. These uncertainties are expressed in terms of Bayesian prior and posterior distributions. A foundation of the procedure is a computer intensive method known as a Bayesian bootstrap. It is used for approximating the posterior distributions of damage probabilities. An 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 the accidental explosions

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

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 smallâ€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 of frequentist (Fisherian) inference is applied to assessing the explosive damage. This technique is called statistical resampling (Efron's bootstrap) and applied as a practical, albeit not equivalent alternative to the Bayesian approaches. It is shown that statistical resampling is capable to yield confidence intervals of damage probabilities and can be applied almost automatically. It operates without using cumbersome methods of statistical inference developed in the classical statistics. The bootstrap confidence intervals do not contain any subjective information except the degree of confidence for which these intervals are computed. The degree of confidence must be chosen by the engineer. The bootstrap confidence intervals are applied to estimating damage probabilities on the basis of the smallâ€size sample of blast loading characteristics. An estimate of the risk of explosive damage is expressed as a set of bootstrap confidence intervals computed for damage probabilities and related outcomes of this damage. Sprogimų sukeliamų pramoninių pastatų pažaidų vertinimas atliekant kartotinį ribotų eksperimentinių duomenų apie sprogimų apkrovas Ä—mimÄ… Santrauka Pramoninių pastatų pažaidų, kurios gali bÅ«ti sukeltos avarinių (atsitiktinių) sprogimų, vertinimÄ… siÅ«loma formuluoti rizikos skaiÄiavimo uždavinio pavidalu. Å i rizika aprÄ—pia nuspÄ—jamų atsitiktinių pažaidų įvykių tikimybes (pažaidų tikimybes) ir padarinius, kurie gali bÅ«ti patirti, pasireiÅ¡kus Å¡iems įvykiams. NagrinÄ—jamas atvejis, kai pažaidas reikia prognozuoti atliekant nedidelį skaiÄių kartotinių eksperimentų ir gaunant santykinai mažą statistinÄ™ sprogimo apkrovų imtį. Pažaidas siÅ«loma vertinti idealizuojant jų kilimo procesÄ… naudojant įvykių medžio diagramas. Teigiama, kad skaiÄiuoti galima kiekvienam diagramos iÅ¡siÅ¡akojimui sudarant pažeidžiamumo funkcijas. Kiekvienas iÅ¡siÅ¡akojimas turi vaizduoti konkreÄiÄ… pažaidÄ…. Pažeidžiamumo funkcijos taikomos sÄ…lyginÄ—ms pažaidų tikimybÄ—ms iÅ¡reikÅ¡ti. Ä®vertinus Å¡ias tikimybes, besÄ…lygines pažaidų tikimybes siÅ«loma vertinti kartotinio statistinio Ä—mimo metodu. Jis laikomas vertinimo, pagrįsto BÄ—jeso statistinÄ—s teorijos metodais, alternatyva. Kartotinis statistinis Ä—mimas leidžia skaiÄiuoti besÄ…lyginiu pažaidų tikimybių pasikliautinuosius intervalus. Taikant šį metodÄ…, galima iÅ¡vengti sudÄ—tingų klasikinÄ—s matematines statistikos procedÅ«rų taikymo. SkaiÄiuojant pasikliautinuosius intervalus kartotinio statistinio Ä—mimo bÅ«du iÅ¡vengiama subjektyvios informacijos. Inžinieriui tereikia priimti subjektyvų sprendimÄ…, kokį pasikliautinumo lygmenį naudoti skaiÄiuojant pasikliautinuosius intervalus. Parodyta, kad Å¡iuos intervalus galima skaiÄiuoti net kai statistinÄ— sprogimo apkrovų imtis yra maža. Sprogimų sukeliamÄ… rizikÄ… siÅ«loma iÅ¡reikÅ¡ti pasikliautinaisiais pažaidų tikimybių intervalais. ReikÅ¡miniai žodžiai: plokÅ¡tÄ—, apdaras, sprogimas, pažaida, impulsinÄ— apkrova, kartotinis statistinis Ä—mimas, stochastinis modeliavimas, pažeidžiamumo funkcija. First Published Online: 14 Oct 201

Trench Fires Resulting from Accidental Releases from Tanker Trucks: Assessing the Thermal Effect on Roadside Territory

The risk posed by spill and subsequent fire during road transportation of flammable liquid is considered in the paper. Attention is paid to a pool fire than can occur in roadside terrain. Circumstances and road situations increasing the likelihood of a spill and fire accident are analysed. The problem under study is an assessment of thermal radiation induced by a roadside pool fire. This study applied a pool fire model known as a trench fire to a roadside situation. The trench fire is considered to be a likely type of a pool fire due to presence of roadside ditches and other oblong low areas along the road. The estimation of the thermal radiation from trench fires is carried out in the deterministic way due to actual lack of systematic uncertainty modelling related to pool fires. Deterministic models developed for estimating the radiation of pool and trench fires are presented and illustrated by a transportation case study. The case study reveals that the thermal radiation emitted by a trench fire can endanger objects positioned in the intermediate vicinity to the road. Further spread of fire into more distant locations is possible only through the domino effect. Incorporation of the thermal radiation models into a transportation risk assessment is discussed in brief. Findings of this study are viewed as knowledge that can be used for refining the estimation of risk posed by transportation of hazardous materials