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1

Numerical simulation on consequences of generator fire accident on offshore platform – a case study

Cao Yang, Honghong Wang, Haodong Wang

Archives of Mining Sciences

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2023

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Vol. 68, no. 2

267--283

EN

The high temperature and thermal radiation caused by generator fire accidents on the offshore platform lead to the destruction of equipment and facilities and threaten the structural safety of the offshore platform. Based on the background of a crude oil generator fire accident on an offshore platform, KFX software was used to conduct a numerical simulation of the fire process and explore the spatial-temporal variation characteristics of smoke, temperature and heat radiation within the scope of the fire room. The influence ranges of 12.5 kW/m2, 25 kW/m2 and 35 kW/m2 were obtained according to the thermal radiation criterion. Researchers examined the temperature variation and heat flow at the room’s ceiling and floor near the primary steel support. The results show that: 1) The surface temperatures of partial steel supports exceed 550°C, and the heat flux of partial steel supports exceeds 37.5 kW/m2. 2) In the ignition position, the maximum temperature at the ceiling reaches 2299°C when t = 24 s, and the maximum temperature at the flooring reaches 701°C when t = 79 s. The heat radiation flux at the ceiling and flooring both exceeds 25 kW/m2. The maximum temperature of partial crude oil generators can reach 1299°C. 3) The heat radiation flux of partial generators can reach 105 kW/m2, and the heat radiation flux at the adjacent point of partial generators never exceeds 20 kW/m2. The above research results can provide a reference for checking the response time of flame detectors and the strength of the supporting structure.

2

FEM study of a steel corrugated web plate girder subjected to fire

Sokołowski D., Kamiński M.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 2

201--218

EN

The main aim of this work is a computational nonlinear analysis of a high strength steel corrugated-web plate girder with a very detailed and realistic mesh including vertical ribs, all the fillet welds and supporting areas. The analysis is carried out to verify mechanical structural response under transient fire temperature conditions accounting for an efficiency and accuracy of three various transient coupled thermo-elastic models. All the resulting stress distributions, deformation modes and their time variations, critical loads and eigenfrequencies as well as failure times are compared in all these models. Nonlinearities include material, geometrical and contact phenomena up to the temperature fluctuations together with temperature-dependent constitutive relations for high strength steel. They result partially from steady state and transient experimental tests or from the additional designing rules included in Eurocodes. A fire scenario includes an application of the normative fire gas temperature curve on the bottom flange of the entire girder for a period of 180 minutes. It is computed using sequentially coupled thermo-elastic Finite Element Method analyses. These account for heat conductivity, radiation and convection. The FEM model consists of a combination of 3D hexahedral and tetrahedral solid finite elements and uses temperature-dependent material and physical parameters, whose values are taken after the experiments presented in Eurocodes. Numerical results presented here demonstrate a fundamental role of the lower flange in carrying fire loads according to this scenario and show a contribution of the ribs and of the welds to the strength of the entire structure.

3

Probabilistic buckling analysis of the beam steel structures subjected to fire by the stochastic finite element metho

Świta P., Kamiński M.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 2

485--510

EN

The main purpose is to present the stochastic perturbation-based Finite Element Method analysis of the stability in the issues related to the influence of high temperature resulting from a fire directly connected with the reliability analysis of such structures. The thin-walled beam structures with constant cross-sectional thickness are uploaded with typical constant loads, variable loads and, additionally, a temperature increase and we look for the first critical value equivalent to the global stability loss. Such an analysis is carried out in the probabilistic context to determine as precisely as possible the safety margins according to the civil engineering Eurocode statements. To achieve this goal we employ the additional design-oriented Finite Element Method program and computer algebra system to get the analytical polynomial functions relating the critical pressure (or force) and several random design parameters; all the models are state-dependent as we consider an additional reduction of the strength parameters due to the temperature increase. The first four probabilistic moments of the critical forces are computed assuming that the input random parameters have all Gaussian probability functions truncated to the positive values only. Finally, the reliability index is calculated according to the First Order Reliability Method (FORM) by an application of the limit function as a difference in-between critical pressure and maximum compression stress determined in the given structures to verify their durability according to the demands of EU engineering designing codes related to the fire situation.

4

On the least squares stochastic finite element analysis of the steel skeletal towers exposed to fire

Kamiński M. M., Strąkowski M. T.

Archives of Civil and Mechanical Engineering

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2013

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Vol. 13, no. 2

242--253

EN

The main issue in this paper is an application of the generalized stochastic perturbation technique to thermal stresses and deformations analysis for the spatial steel tower structure exposed to a fire. This approach is based on the given order Taylor expansion of all random parameters and state functions around their mean values as well as on the Least Squares Technique to determine the analytical functions in-between design parameters and structural responses. A distribution of the temperature in the model is considered for a simplicity as the set of constant values for all structural members. The temperature equivalent to the fire exposure in the analyzed structure is taken as the input Gaussian random variable, where basic material parameters are considered as temperature-dependent and this is the basis to calculate up to the fourth probabilistic moments and characteristics of the stresses and deformations. This study is an example of a hybrid usage of the FEM engineering system ROBOT and the computer algebra system MAPLE in stochastic analysis, where thermal stresses and strains may be straightforwardly used in fire reliability analysis of the civil engineering structures with both temperature-independent and dependent material characteristics.

5

Propozycja optymalizacji zagrożenia pożarowego z użyciem automatów komórkowych

Czerniak J., Znaczko A.

Metody Informatyki Stosowanej

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2009

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nr 4 (21)

5-16

PL

Przedstawione eksperymenty pozwoliły potwierdzić w sposób symulacyjny, że niefrasobliwe lub bezprawne odcinanie dróg ewakuacji budynków grozi na każdym etapie eksploatacji poważnymi konsekwencjami. Osoby odpowiedzialne za inspekcje ppoż. i budowlane mogą sięgnąć tego typu narzędzi, aby uzasadnić swoje wydawałoby się zbyt restrykcyjne decyzje. Żeby uczynić symulację jeszcze bardziej rzeczywistą warto zastanowić się nad możliwością automatycznej zmiany w programie parametru prawdopodobieństwa podążania do wyjścia. Jest faktem powszechnie znanym, iż z analizy przyczyn i warunków katastrof wynika, że prawdopodobieństwo ocalenia maleje w takt upływającego czasu. Kolejne eksperymenty powinny, zatem ten fakt uwzględniać.

EN

This paper explains the rule of cellular automata operation as well as presents their structure and fields of application. It includes basic concepts as regards cellular automata and presents simulation of fire hazards inside buildings. The paper also indicates to practical applications of the cellular automata theory for building fire simulation using the programme Symulacja pożaru. Thanks of the tests carried out using appropriately configured programme, realistic results of simulated evacuation of people from the building have been achieved. Using such kind of predication in civil engineering should increase the fire safety of buildings. Simulations described in this paper seem to be very useful, particularly in case of building renovation or teinporary unavailability of escape routes. Using them, it is possible to visualise potential hazards and to avoid increased risk in case of fire. lnappropriate operation of buildings, including insouciant planning of renovations are among frequent reasons of tragic accidents cited by fire brigade information services. Thanks to the proposed solutions it is easier to envisage consequences of problematic decisions causing temporary or permanent unavailability of escape routes.