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 problem of sprinkler reliability

Sprinkler systems allow a considerable reduction of fire risk in buildings. Unfortunately, sprinklers are not failsafe technical systems. Relatively high rates of sprinkler failures evoke the problem of reliability. A solution to this problem is considered from several viewpoints. The diversity of sprinklers' failure modes is the first challenge for estimating reliability (failure probability). It is found that the use of the available data for estimation is problematic. The second challenge is that the published data is insufficiently described to allow a verification of its relevance to the specific case of failure probability estimation. It is suggested to apply the published data with partial relevance to Bayesian inference about failure probabilities. The data is used for developing prior distributions of the unknown values of the probabilities. Bayesian inference is carried out on the basis of binomial distribution used to model the operation of sprinklers on demand basis. A problem of aging and a possible increase in failure probability in the course of sprinkler service is shortly discussed. Sprinklerių patikimumo problema Santrauka. Nagrinėta sprinklerių sistemų patikimumo vertinimo problema. Patikimumo matu laikoma sprinklerių atsako tikimybė. Rasta, kad šios tikimybės vertinimas yra sąlygiškai sudėtingas uždavinys. Sprinkleriai gali patirti atsaką labai įvairiais būdais. Be to, šis atsakas patiriamas retai. Tai lemia duomenų apie sprinklerių neįsijungimo gaisro metu negausumą, neleidžia vertinti atsako tikimybės, remiantis klasikiniu santykinio dažnio požiūriu. Patikimumo vertinimą komplikuoja tai, kad duomenys apie sprinklerių atsakus renkami gana nesistemingai, be teorinio pagrindo ir standartizavimo šalies, regiono ar pasaulio mastu. Duomenys paprastai fiksuojami pasyviai, kai sprinkleriai neįsijungia gaisro metu. Turimi empiriniai sprinklerių atsako dažniai gali būti naudojami kaip šiurkštūs tikimybių įverčiai. Juos galima taikyti Bajeso analizei, kai reikia formuoti apriorinį atsako tikimybės tankį. Šį tankį galima atnaujinti pasitelkiant negausius duomenis, surinktus konkrečioje šalyje, ir gautus stebint konkretaus tipo sprinklerius. Teorinis modelis kuriuo galima nusakyti sprinklerių atsakų tikėtinumą per pasirinktą gaisrų skaičių, yra binominis skirstinys. Sprinklerių atsako tikimybės vertinimą galima atlikti taikant standartinę binominio skirstinio parametro vertinimo procedūrą Bajeso statistikos metodais. Pagrindinė binominio skirstinio prielaida yra ta, kad sprinkleriai nesensta ir jų atsako tikimybė nesikeičia laikui bėgant. Galima spėsti, kad ši prielaida yra neteisinga. Deja, duomenų, kurie galėtų patvirtinti arba paneigti tą prielaidą, trūksta. Be tokių duomenų, nebus galima parinkti modelio, kuris nusako atsako tikimybės didėjimą sprinklerius eksploatuojant. Taigi sprinklerių senėjimas ir jų atsako tikimybės didėjimas tėra tik teorinė prielaida, kurią sunku įtraukti į sprinklerių patikimumo vertinimą. Reikšminiai žodžiai: sprinkleriai, gaisras, Bajeso požiūris, daugiakriterė atranka

Daugiatikslės analizės ir rizikos skaičiavimo derinimas vertinant pastatų gaisrinę saugą

The dissertation presents an approach to a building-related multi-attribute selection (multiple criteria decision making) which takes into account the fire safety of buildings. It is investigated how to incorporate fire risk measures into the standard scheme of such a decision making and found the way how to solve decision making problems in an unconventional situation when fire risk measures are expressed by random variables. The dissertation consists of introduction, three chapters, conclusions, lists of references and papers published by the author of the dissertation, as well as eight annexes. Chapter 1 presents a review and evaluation of the published work on the multi-attribute selection, building fire risk assessment and fire risk indexing. The review addresses also evaluation of fire safety by means of two approaches: fire risk indexing and fire risk assessment. Pros and cons of either approach are analysed. Chapter 2 proposes a formulation and solution of several problems of multi-attribute selection applied to making decisions which take into account the fire safety of buildings. Three selection problems are considered: selection of a cost-effective fire safety system, selection among several alternative buildings with regard to fire safety of each of them and choice between alternative fire protective measures with respect to fire risk. Decision matrices of these selection problems are formulated as deterministic ones and random ones. The former are used for a conventional multi-attribute selection and the latter are integrated in the process of a simulation-based uncertainty propagation which allows to solve the selection problem in an unconventional way. Chapter 3 describes a combined application of multi-attribute selection and fire safety assessment to making decisions concerning medical facilities. An increased fire risk level in medical occupancies is identified and illustrated by fire incident data. Three examples of the multi-attribute selection with respect to fire safety are presented. The first example considers a selection of a fire safety system for a hospital building. The second example deals with a multi-attribute selection of a building for a nursing home. In these two examples, fire safety is quantified by means of fire risk indices. The third example describes a multi-attribute selection among several alternative designs of a floor in a hospital building. Fire safety is expressed through the risk to lives of patients and hospital personnel. The attribute considering this risk is quantified as time to untenable conditions in rooms of the building under analysis. The main statements of the dissertation were published in six scientific articles: three articles – in the Thomson ISI Web of Science register, three articles – in other editions

A comparison of methods used for fire safety evaluation

The paper considers the problem of fire safety assurance by means of fire risk indexing and fire risk assessment. Attention is focused on the comparison of these two principal approaches and the possibilities of applying them in a combined set. The paper is aimed at defining, comparing and analyzing fire safety assessment by applying the aforementioned approaches. The practicability of both approaches is compared by means of an example considering fire safety of an existing office building. It is stated that fire risk indexing is more practicable than formal risk assessment despite all shortcomings of the former approach. It is highly probable that comprehensive decision-making concerning fire safety assurance will be based on fire risk indexing rather than on formal risk assessment. Article in English. Gaisrinės saugos vertinimo metodų palyginimas Santrauka. Gaisrinės rizikos indeksai ir formalus rizikos vertinimas yra du pagrindiniai metodai, taikomi vertinant gaisrinę saugą. Šiame straipsnyje yra trumpai apžvelgiami šie metodai, pateikiami jų privalumai bei trūkumai ir jie tarpusavyje palyginami. Pateikiamas pavyzdys, iliustruojantis gaisrinės saugos indeksų ir rizikos vertinimo pritaikymą biuro pastatui. Nustatyta, kad gaisrinės rizikos indeksai yra paprastai skaičiuojami ir lengvai pritaikomi praktikoje, tačiau jie turi esminių trūkumų. Jų taikymas yra greičiau susitarimo reikalas ir jie nėra pagrįsti griežta moksline metodologija. Be to, įvairiose šalyse taikomi įvairūs indeksai. Gaisro rizikos vertinimas grindžiamas kiekybine rizikos vertinimo metodologija. Toks vertinimas atliekamas taikant griežtas tikimybinio skaičiavimo taisykles ir išnaudojant statistinius duomenis bei ekspertų nuomones. Tačiau formalus rizikos vertinimas yra santykinai sudėtingas ir reikalauja aukštos matematinės kvalifikacijos. Tikėtina, kad priimant kompleksinius sprendimus, susijusius su pastato gaisrine sauga, jos užtikrinimas bus grindžiamas gaisro rizikos indeksais, o ne formaliu rizikos vertinimu. Reikšminiai žodžiai: gaisras, sauga, indeksas, vertinimas, rizika

Priešgaisrinės saugos praktinio mokymo tyrimas

Pati dažniausia ir pavojingiausia stichija, su kuria tenka susidurti žmonėms, – tai ugnis. Gaisras yra nekontroliuojamas degimo procesas, kurio metu plintanti ugnis, aukšta temperatūra ir dūmai sudaro pavojų pastate esantiems žmonėms ir palieka didelius socialinius ir ekonominius padarinius. Atsidūrus ekstremalioje situacijoje, ypač svarbios tampa automatinės (psichomotorinės) reakcijos. Tuo tikslu žmonės turi būti apmokyti, kokių veiksmų imtis, kilus gaisrui, kaip saugiai elgtis ir evakuotis iš pastatų. Net vienas žuvęs gaisre yra perdaug

Solving the problem of multiple-criteria building design decisions with respect to the fire safety of occupants: an approach based on probabilistic modelling

The design of buildings may include a comparison of alternative architectural and structural solutions. They can be developed at different levels of design process. The alternative design solutions are compared and ranked by applying methods of multiplecriteria decision-making (MCDM). Each design is characterised by a number of criteria used in a MCDM problem. The paper discusses how to choose MCDM criteria expressing fire safety related to alternative designs. Probability of a successful evacuation of occupants froma building fire and difference between evacuation time and time to untenable conditions are suggested as the most important criteria related to fire safety. These two criteria are treated as uncertain quantities expressed by probability distributions. Monte Carlo simulation of fire and evacuation processes is natural means for an estimation of these distributions. The presence of uncertain criteria requires applying stochastic MCDM methods for ranking alternative designs. An application of the safetyrelated criteria is illustrated by an example which analyses three alternative architectural floor plans prepared for a reconstruction of a medical building. A MCDM method based on stochastic simulation is used to solve the example problem

Multi-attribute decision-making in economics of fire protection

The economic decisions concerning fire safety of built property may involve alternative solutions (alternatives) of fire protection measures, comparison of buildings with different fire safety levels, choice among construction products with different properties of performance in fire. The need to choose among alternatives may be faced by various interested parties: fire safety regulators (authorities on national level), insurers, architects (building designers), manufacturers of fire protection measures, property owners and buyers. The problem of choice will often involve the need to consider simultaneously several characteristics (attributes) of alternatives, and those related to fire safety will be accompanied by economic and non-economic ones. Such a choice can be formalised as a problem of multiattribute selection (MAS), a filed known also as multicriteria decision making (MCDM). The present paper aims to formulate and solve several problems of multi-attribute selection by taking into account attributes related to fire safety. The problems are considered in an attempt to facilitate decision-making on three levels: the level of a property buyer/renter, the level of a property owner, and the level of an architect (building designer). It is shown that a different level of decision making requires to apply attributes of different nature. The well-developed field of fire safety offers a range of quantitative and qualitative indicators describing fire performance of building materials, construction and fire protection products as well as entire buildings. These indicators are introduced, with relative ease, into MAS problems

A brief look at data on the reliability of sprinklers used in conventional buildings / Trumpa duomenų apie įprastiniuose pastatuose įrengtų sprinklerių patikimumą apžvalga

Failures of sprinklers to extinguish fires generate a basic need for the assessment and increase of reliability of these crucial safety systems. This in turn creates a demand for input data used for reliability assessment. Broadly speaking, data on sprinkler failures are available in large amounts and some countries have well-established systems of data collection and reporting. Data are accumulated in the sprinklered environments of conventional buildings and some industrial facilities. The compilation of data sets necessary for reliability assessment may face several problems: differences in definition and naming failure modes; differences in the failure of data reporting; the prevalence of a human factor among the causes of sprinkler failures in a conventional building; the influence of ageing, modifications and repairs on sprinkler reliability. The size of data sets can be limited by such factors as limited relevance of data collected in different sprinklered environments, differences in operation conditions and components, ageing of data collected in the past, the concealment of data and/or a high cost of data, poor documentation and explanation of data in available databases. Data on sprinkler component failure rates necessary for fault tree models can be extracted from generic databases. However, databases containing information on the failure rates of sprinkler-specific components do not seem to exist in literature or on the Internet. Scarce data on sprinkler failures can be utilised within the Bayesian format. The potentially critical issue of reliability dependence on sprinkler aging and other changes in time remains unsolved from the standpoint of both theoretical modelling and data collection. Santrauka Nereti sprinklerių atsakai, gesinant gaisrus, verčia vertinti šių kritinių saugos sistemų patikimumą. Dėl to reikia kaupti ir apdoroti duomenis, kurių reikia vertinant patikimumą. Duomenų apie sprinklerių atsakus yra daug. Kai kurios šalys turi gerai sudarytas sprinklerių patikimumo duomenų rinkimo ir skelbimo sistemas. Duomenys renkami apie sprinklerius, įrengtus tiek įprastiniuose pastatuose, tiek pramoniniuose objektuose. Tačiau duomenų patikimumui vertinti rinkimas susiduria ir su kai kuriais sunkumais. Nėra sutartinės sprinklerių atsakų apibrėžimo ir įvardijimo praktikos, ataskaitos apie atsakus dažnai labai skiriasi, patikimumo vertinimą sunkina ir tai, kad vyraujanti įprastinių pastatų sprinklerių atsakų priežastis yra žmonių klaidos. Patikimumo vertinimą apsunkina ir sprinklerių senėjimo reiškinys, sistemų modifikavimai ir remontai. Patikimumo duomenų kiekį riboja ir tai, kad duomenys, gauti skirtingose eksploatavimo aplinkose, tinka tik toms aplinkoms. Sprinklerių eksploatacija ir aplinkos sąlygos gali būti skirtingos. Duomenų kiekį riboja ir jų kaina, senėjimas bei slėpimas. Duomenys, kaupiami kai kuriose bazėse, būna nepakankamai paaiškinti ir netinkamai dokumentuoti. Kai sprinklerių sistemos patikimumas vertinamas taikant atsakų medžio analizę, įvesties duomenys gali būti gauti ir iš bendrųjų patikimumo duomenų bazių. Tačiau literatūroje ir internete negalima rasti duomenų bazės, kurioje būtų sukaupti duomenys būtent apie sprinklerių sistemų komponentų patikimumą. Kai patikimumo duomenų trūksta, jį galima vertinti taikant Bajeso metodus. Tiek teorinis modeliavimas, tiek duomenų rinkimas šiandien dar neleidžia atsižvelgti į fizinį sprinklerių senėjimą bei modifikacijas, kurios gali labai paveikti šių sistemų patikimumą. Reikšminiai žodžiai: sprinkleriai, gaisras, duomenų šaltinis, duomenų bazė, patikimumas, atsako dažnis, senėjimas, žmogaus klaid

Fire Risk Indexing and Fire Risk Analysis: A Comparison of Pros and Cons

The paper considers the problem of fire safety assurance by means of fire risk indexing and fire risk assessment. The attention in focused on the comparison of these two principal approaches and possibilities of their application in a combined set. The paper aims to define, compare and analyse fire safety assessment by applying the aforementioned approaches. The practicability of both approaches is compared by means of an example which considers fire safety of an existing office building. It is stated that it makes sense to combine the merits both fire risk indexing and assessment in order to apply them to a comprehensive decision-making concerning fire safety assurance. The paper also states that this can be done within the framework of a multi-attribute decision-making methodology