Prediction of fire origin location to wood materials charring ; Gaisro kilimo vietos nustatymas pagal medinių konstrukcijų apanglėjimą

Jolanta Bak

Description

Donatas LIPINSKAS PREDICTION OF FIRE ORIGIN LOCATION TO WOOD MATERIALS CHARRING Summary of Doctoral Dissertation Technological Sciences, Civil Engineering (02T) 1341 Vilnius 2006 VILNIUS GEDIMINAS TECHNICAL UNIVERSITY Donatas LIPINSKAS PREDICTION OF FIRE ORIGIN LOCATION TO WOOD MATERIALS CHARRING Summary of Doctoral Dissertation Technological Sciences, Civil Engineering (02T) Vilnius 2006 Doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2002–2006 Scientific Supervisor Prof Dr Habil Romualdas MAČIULAITIS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T) The dissertation is being defended at the Council of Scientific Field of Civil Engineering at Vilnius Gediminas Technical University: Chairman Prof Dr Habil Audronis Kazimieras KVEDARAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T) Members: Assoc Prof Dr Petras ČYRAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T) Prof Dr Habil Edmundas Kazimieras ZAVADSKAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering – 02T) Prof Dr Habil Vladimiras GAVRIUŠINAS (Vilnius University, Physical Sciences, Physics – 02P) Prof Dr Habil Aivaras KAREIVA (Vilnius University, Physical Sciences, Chemistry – 03P) Opponents: Prof Dr

Sujets

• Wood

Informations

• Publié par: vilnius_gediminas_technical_university
• Publié le: 01 janvier 2007
• Nombre de lectures: 38

Extrait

 

        Donatas LIPINSKAS         PREDICTION OF FIRE ORIGIN LOCATION TO WOOD MATERIALS CHARRING         Summary of Doctoral Dissertation Technological Sciences, Civil Engineering (02T)      

 

  Vilnius 2006

1341    

 

VILNIUS GEDIMINAS TECHNICAL UNIVERSITY                   Donatas LIPINSKAS         PREDICTION OF FIRE ORIGIN LOCATION TO WOOD MATERIALS CHARRING           Summary of Doctoral Dissertation Technological Sciences, Civil Engineering (02T)        

 

  Vilnius 2006

 

Doctoral dissertation was prepared at Vilnius Gediminas Technical University in 20022006   Scientific Supervisor Prof Dr Habil Romualdas MA Č IULAITIS  (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering  02T)   The dissertation is being defended at the Council of Scientific Field of Civil Engineering at Vilnius Gediminas Technical University: Chairman Prof Dr Habil Audronis Kazimieras KVEDARAS  (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering  02T)   Members: Assoc Prof Dr Petras Č YRAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering  02T)   Prof Dr Habil Edmundas Kazimieras ZAVADSKAS  (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering  02T) Prof Dr Habil Vladimiras GAVRIUINAS (Vilnius University, Physical Sciences, Physics  02P) Prof Dr Habil Aivaras KAREIVA  (Vilnius University, Physical Sciences, Chemistry  03P) Opponents: Prof Dr Arvydas JUODIS  (Kaunas University of Technology, Technological Sciences, Civil Engineering  02T) Prof Dr Habil Gintaris KAKLAUSKAS (Vilnius Gediminas Technical University, Technological Sciences, Civil Engineering  02T)   The dissertation will be defended at the public meeting of the Council of Scientific Field of Civil Engineering in the Senate Hall of Vilnius Gediminas Technical University at 12 a. m. on 26 January 2007. Address: Saul ė tekio al. 11, 10223 Vilnius, Lithuania Tel.: [phone]; fax [phone]; e-mail: [e-mail]   The summary of the doctoral dissertation was   distributed on 22 December 2006 A copy of the doctoral dissertation is available for review at the Library of Vilnius Gediminas Technical University (Saul ė tekio al. 14, Vilnius, Lithuania)   © Donatas Lipinskas, 2006

 

 

  VILNIAUS GEDIMINO TECHNIKOS UNIVERSITETAS                   Donatas LIPINSKAS       GAISRO KILIMO VIETOS NUSTATYMAS PAGAL MEDINI Ų KONSTRUKCIJ Ų   APANGL Ė JIM Ą             Daktaro disertacijos santrauka Technologijos mokslai, statybos ininerija (02T)    

 

  Vilnius 2006

 

 

Disertacija   rengta   20022006   metais   Vilniaus   Gedimino   technikos universitete.   Mokslinis vadovas prof. habil. dr. Romualdas MA Č IULAITIS  (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos ininerija  02T).   Disertacija ginama Vilniaus Gedimino technikos universiteto Statybos ininerijos mokslo krypties taryboje: Pirmininkas prof. habil. dr. Audronis Kazimieras KVEDARAS (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos ininerija  02T). Nariai: doc. dr. Petras Č YRAS  (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos ininerija  02T), prof. habil. dr. Edmundas Kazimieras ZAVADSKAS  (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos ininerija  02T), prof. habil. dr. Vladimiras GAVRIUINAS (Vilniaus universitetas, fiziniai mokslai, fizika  02P), prof. habil. dr. Aivaras KAREIVA  (Vilniaus universitetas, fiziniai mokslai, chemija  03P). Oponentai: prof. dr. Arvydas JUODIS  (Kauno technologijos universitetas, technologijos mokslai, statybos ininerija 02T),  prof. habil. dr. Gintaris KAKLAUSKAS (Vilniaus Gedimino technikos universitetas, technologijos mokslai, statybos ininerija  02T).   Disertacija bus ginama vieame Statybos ininerijos mokslo krypties tarybos pos ė dyje 2007 m. sausio 26 d. 12 val. Vilniaus Gedimino technikos universiteto senato pos ė di ų sal ė je. Adresas: Saul ė tekio al. 11, 10223 Vilnius, Lietuva. Tel.: [phone]; faksas [phone]; el. patas [e-mail]   Disertacijos santrauka isiuntin ė ta 2006 m. gruodio 22 d. Disertacij ą  galima peri ū r ė ti Vilniaus Gedimino technikos universiteto bibliotekoje (Saul ė tekio al. 14, Vilnius, Lietuva) VGTU leidyklos Technika 1341 mokslo literat ū ros knyga   © Donatas Lipinskas, 2006

 

 

1. General Characteristic of the Dissertation   Topicality of the problem . Most countries for constructing low-rise buildings apply mostly wood in manufacturing of various structures (bearing structures of roofs, walls, beams, columns and etc.). In cases of fire these buildings manifest mostly such evidences of burning which are called charring of wooden parts (structural elements). For investigators of fire it is relevant to find the connection of this feature with certain significant effects of fire, namely its duration or temperature, in order to be able to determine the exact location of the fire start (spot/source) as well as the cause of initiation (reason). The dynamics of fire aggravates the determining of accuracy of determining the duration of wood burning, because in wooden structures there are enacted many additional physical-chemical processes. These processes make a great influence on fire resistance of structures, on the influence of the knowledge on different fields. Well known professionals consider that the attention to charring rate under the analysis of fire is paid a too narrow one and played as inadequately considerable role. In our country there have been so far applied the remarks and recommendations of Russian scientists, regarding charring rates, there are presented generalized charring rates of wood, the particularity of coal layer measurements is discussed, the calculation of burning duration taking into account theoretical and instrumental methods , however without mentioning the influence of majority of factors, relevant for today.   Aim and tasks of the work . The task of the work is to exhibit the way the justified and precisely analyzed various cases of charring a well as appropriate detailed investigation of charring processes and measurements are possible to be applied for finding out the location of fire origin. It is useful to perfect the technique for determining the place of fire origin in order to achieve that task. It is intended for the new method to be able to allow more accurately to determine the influence of fire on wooden structures from the point of view of temperature and duration, as well as it could simplify the process of carrying out the main goal of research on fire, namely to detect the exact place of fire start and the reasons of fire outbreak. The following scientific and technical objectives have been defined to fulfill the target of the work: 1. Impartially apply the methods of tests carried (special chamber of single- sided heating of structures, SBI (Single Burning Item) equipment and etc.) and to carry out research on wood charring, to make efforts to evaluate wood density, humidity and density of heat flow.

5

 

2. To decide on the influence of natural wood and wood with fire retardants on the amount of heat, required for evaporation of volatile products of wood and for time period (called inductive time), that lasts till the moment since which   the charring depth is performed at the speed more quicker and closer to the regular one. 3. To justify the mentioned parameters by SBI method of indices (total heat (THR (600)), fire increase rate (FIGRA) and increase of smoke amount (SMOGRA)) by average values. 4. To set the coefficient value of free oxygen inflow into the zone of burning by means of SBI testing facility. 5. To evaluate on the basis of the received new experimental data the reliability of the method for determining the previous fire outbreak location. 6. By means of mathematical statistics there has been derived new dependence of calculation reliance concerning wood charring rate and duration of burning and to check their accuracy. 7. To compare the old and new methods based on the particular realistic data of fire expertise, presenting the advantage of new method from the point of view of accuracy.   Scientific novelty . For the first time there have been used these parameters to detect the location of fire origin in a complex way by applying simple engineering methods: wood density and moisture, types of wood, density of heat flow, amount of heat required to fully evaporate volatile products from dry wood, for measures of safety protection (fire retardants) and etc.   Materials and methodology of research . For the research there were used several types of wood, coniferous (pines and firs) and leafy woods (oaks and ashes), protected and non-protected by fire retardants, fragments of structures. As measures of protection there were used the fire retardants Flamasep or BAK1. The samples of a determined size (300×300×500 mm) have been saturated for 10 hours in the solution of fire retardant; later have been dried naturally to the moisture degree required by the research not exceeding 15 % of mass. Density of the non proofed sort of wood has been considered: for fir trees  435 kg/m 3 , for pines  455 kg/m 3 , for ashes  680 kg/m 3 , for oaks  720 kg/m 3 . In order to determine charring rate differences for different sorts of wood protected and no-protected by fire retardants as well as their influence on the final result of forecasting there have been used:  Special single sided heating chamber, the width and height of the samples  300×300 mm, their thickness from 350 to 700 mm. The principle of the

6

 

experiment is to heat the sample from one side in accordance with the strictly prescribed temperature-time subjection.  LST EN 13823:2002 SBI method which imitates conditions of fire for huge structural elements in maximum approximating the conditions of samples to the real circumstances of fire. When testing by following SBI, the sample is thermally affected by 30,7 ± 2,0 kW power of burner which is located at the bottom of the corner. The sample consists of two vertical wings comprising the angle. The shorter angle has got the following dimensions: 495 ± 5 mm x 1500 ± 5 mm, the longer wing have got the following dimensions: 1000 ± 5 mm x 1500 ± 5 mm. The dimensions of the burning chamber are 3 m x 3 m, the total height of the installation is approximately 4,2 m. The electric resistance of coal samples has been measured in the Centre of research of Fire Brigades using the equipment possessed there in accordance with the predetermined sequence of measurements. The regressive analysis of the received data has been carried out by the help of software packet STATISTICA 6.0.   Practical value . Based on the research there has been compiled the reliance of calculating charring rates and legalized the method for determining the location of fire origin. Determining of Fire Origin Location in Buildings of Wooden Structures (GTC/GT 5). The new technique has been implemented at the Department of Fire Protection and Rescue at the Ministry of Interior at the Fire Research Centre of Examination Division.   Defended propositions      By using various facilities for testing there have been made experimental • tests on charring for fir, pine, ash and oak samples, in trying to determine the prevailing tendencies influencing the particularity of charring process: wood density and moisture, density of heat flow, amount of heat, required for evaporation of volatile products of wood. •   For proofed wooden samples there has been registered influence of fire retardants BAK1 and FLAMASEP on the indices of heat amount, required for evaporation of volatile products of wood, inductive time, fire increase rapidity, amount of smoke increase and total data. •   There has been determined the maximum coefficient of amendment k d for the results of tests under the circumstances of real standard fire using standard facilities, for evaluating free available oxygen inflow into the zone of burning and unlimited convection, in accordance with the results of SBI research method.

7

 

•  By the help of the experimental data there has been proved low correlation of the prediction method concerning old fire origin location and unsatisfactory reliability in comparison with high correlation of a new method the practical value of which and positive reliability are based on the data of real fire expertise.   The scope of the scientific work.  The scientific work consists of the general characteristic of the dissertation, 5 chapters, conclusions, list of literature, list of publications. The total scope of the dissertation  129 pages, 56 pictures, 14 tables and 5 addenda.   2. Special single sided structure chamber for heating and the results of the research available by SBI facilities   In using special facilities for heating chamber of single sided structure there have been investigated the samples of tiny dimensions (Fig 1). There has been determined that the charring depth under the conditions of standard fire and at the same time is not even for different sorts of wood. The charring rate for coniferous wood is 0,80,9 mm/min, leafy wood and proofed coniferous wood is 0,50,6 mm/min, and for proved leafy wood is 0,30,4 mm/min. As these data exhibit the charring rate of different sorts of wood, to use fire retardants for wood from the point of view of charring rate is effective. Differences of charring rates between the pine, fir, oak and ash are insignificant and get into the previously mentioned charring rate margins.  

   a b Fig 1. Test of pine charring rate under standard fire: a  before test, b  after test   During testing there have been received data of charring rate similar to those of Eurocode 5 concerning coniferous (softwood) and leafy (hardwood) assumed charring rates. Here are presented the following values of charring rates: for coniferous wood, density of which is ≥ 290 kg/m 3  β n   = 0,8 mm/min, for leafy wood density of which is ≥  450 kg/m 3   β n   = 0,55 mm/min. So we have been proved that the facilities applied for the fragments of wooden structures in case of standard fire are proper and suitable and the results are

8

 

satisfactorily reliable. It is significant to mention that the efficiency of proofing coniferous woods is much higher than for leafy wood. After 10 min duration of standard fire the effect of pine charring rate amounts to 0,8 mm/min, in case it is proofed by the test of the same 10 min duration which exhibits the charring rate 0,3 mm/min, difference of 0,5 mm/min is high enough. In case of oak wood after 10 min charring rate is 0,3 mm/min, and proofed oak is 0,1 mm/min and the difference is 0,2 mm/min. That could be explained by the fact that the possibilities of soaking with fire retardant of different woods differ (after 10 hours of soaking of coniferous wood (pine and fir) the depth of proofing is 710 mm, for leafy wood (oak and ash), the density of which is much higher, the depth of proofing is 35 mm). The greatest charring rate differences between proofed and non-proofed wood is at the beginning of standard fire happening, then the peculiarities of fire retardants of protection are expressed the most vividly. The charring rate without taking into account the type of wood, increases gradually together with the rise of the temperature. Only later in 3035 min in case of standard fire, charring rate becomes nearly fixed. After the experiment of standard fire there has been determined the fact on the presence of the absence of significant difference between coniferous and leafy wood induction time   τ o   (min), that is there are time segments the duration of which lasts till the moment since which the charring into depth process starts at the rate similar to the uniform. However the wood with means of protection charring process due to the influence of protecting materials starts considerably later. Wood with protective materials (fire retardants) induction time τ oi   (min) is well described the equation presented below which submits the dependence of test data:     τ oi = 940,101· T,  (1)   where τ oi   is the induction time of proofed wood, i.e. segment of time, that lasts till the time since which the process of depth charring has already started at the rate close to the permanent; T  is temperature (K). Based on the results of heating chamber of single sided structure there have been carried out the calculation of values of fire duration by means of an old method, there have been determined that in case of coniferous the predicted duration of fire effect (56 min) practically coincides with real standard effect of fire duration is 60 min. Meanwhile for the leafy wood especially when it is protected by fire retardants the accuracy of prediction is reduced. Then after the effect of standard fire for 60 min the prediction of fire effect duration is equal 18 min. During 1 hour period there has been caused more than 40 min

9

 

difference. In order to determine more precise fire parameters (charring rate, fire duration, fire origin location), it is important to evaluate the influence of wood density, moisture, heat flow density and heat amount, necessary for discharge of volatile products. Further investigation on charring of wood using the facilities of SBI method (Fig 2), makes the corrections of the previously received values on charring rates and depth.  

    Fig 2. Single Burning Item Testing Facility General View   There have been determined that irrespective to what sort of wood is applied and if it is protested by fire retardants or not, the charring rate is more active by 20 %, because during 25 min the charring rate of pine boards is equal to 0,951,1 mm/min, and for proofed coniferous boards within 25 minutes charring rate is equal to 0,60,75 mm/min. By means of SBI method and heating facility of special single sided structure the obtained data on charring depth from the point of view of time are comparable and presented in Fig 3.   30     25 20   1 a 15   1 b   10   2 a   5   2 b 0   0 5 10 15 20 25 30   Simulated fire impact time τ , min   Fig 3. Charring depth dependence on time tested by different methods: 1  pine; 2  pine proofed by fire retardant  BAK 1  ; a  SBI method; b  heating facility of special single-sided structure

10