Current research at the University of Canterbury is investigating the performance of a new type of timber floor system made of a timber-concrete composite. This newly proposed timber floor system uses double LVL members connected together with screwed connections to form one larger LVL member. Recent large scale fire tests showed that the joint between these two screwed LVL members opened up during fire exposure. This opening phenomenon causes concerns as the overall charring rate of the joint LVL members is subsequently increased. The main focus of this research, therefore, was to examine the charring rate for different cross sections of single and double LVL members, with different connection types for the double members. The single LVL member examined was 63mm width whereas the double LVL members examined were 90mm and 126mm width. Three connection types were investigated which were nails, screws and glue. Their corresponding charring rates and burning characteristics were examined both in the small furnace provided by the University of Canterbury and in the pilot furnace at the Building Research Association of New Zealand (BRANZ) in Wellington. The overall finding from the small furnace testing shows that the overall average side charring rate for a 30 minute fire exposure was 0.76mm/min; whereas the overall average side charring rate for a 60 minute fire exposure was 0.66mm/min. Moreover for a 30 minute fire exposure, the average bottom charring rates for nail, screw and glue connected double LVL members were 1.00mm/min, 0.83mm/min and 0.83mm/min, respectively. For a 60 minute fire exposure, the average bottom charring rates for screw and glue connected double LVL members were 0.97mm/min and 0.57mm/min, respectively. The nail connected double LVL members experienced the highest bottom charring rate as it suffered the largest bottom separation which allowed the heat to travel into the mid-span resulting in a higher bottom charring rate. Out of these three connection types, the glued connection was the best connection type. Experimental findings were compared with the simulated results generated by the SAFIR finite element program. Experimental findings were also used to modify the spreadsheet design tool which predicts the fire resistance rating of a timber-concrete composite floor under user defined load conditions and floor geometries.

A taxa na qual a madeira se converte em carvão é determinante para a avaliação da resistência ao fogo, pois o colapso de elementos estruturais de madeira e de seus derivados quando expostos ao fogo ocorre principalmente pela redução da área resistente da seção, devido à formação de carvão. A resistência ao fogo depende, portanto, das dimensões da seção transversal que é reduzida gradualmente ao ser exposta ao fogo. Vários países têm investido em pesquisas para a caracterização e determinação da taxa de carbonização com base em diferentes espécies. Nesse trabalho são apresentados dois modelos de taxa de carbonização para a madeira de Eucalyptus das espécies citriodora e grandis, de grande interesse para aplicação estrutural e plantadas no Brasil. Um para peças de madeira com pequena dimensão (17,2 cm x 17,2 cm x 6,0 cm) e outro para as vigas estruturais (0,16 cm x 0,26 cm x 2,00 m). A curva de aquecimento adotada foi a recomendada pela ASTM E-119. / The rate at which the wood converts in char is determinant to evaluate the wood fire endurance, because the failure of wooden structural elements and its composites exposed to fire occurs through reduction of cross section. The fire resistance depends on cross sections dimensions that are gradually reduced when exposed to fire. Several countries have invested in research to determine the wood charring used for building construction that result in the establishment of values to different species. This work presents two charring rate models for citriodora and grandis species of Eucalyptus, that presents structural interests in assemblies in Brazil. One model for small pieces (17,2 cm x 17,2 cm x 6,0 cm) and the other using structural beam ( 0,16 cm x 0,26 cm x 2,00 m). The standard temperature x time curve was ASTM E-119.

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... [to full text] / Daugelyje šalių mažo aukštingumo namų statybai gaminamoms įvairioms konstrukcijoms (stogų laikančiosioms konstrukcijoms, sienoms, sijoms, ir kt.) dažnai naudojama mediena. Kilus gaisrui tokiuose pastatuose, labiausiai iš visų degimo požymių yra pastebimas medžio detalių (konstrukcijos elementų) apanglėjimas. Gaisro tyrinėtojams ypač aktualu susieti šį požymį su tam tikrais svarbiais gaisro poveikiais, pvz., jo trukme ar temperatūra, kad būtų galima nustatyti tikslią gaisro kilimo vietą (židinį) bei kilimo būdą (priežastį). Gaisro dinamika apsunkina medienos degimo trukmės nustatymo tikslumą, nes medinėje konstrukcijoje vyksta daug papildomų fizikinių-cheminių procesų. Šie procesai daro didelę įtaką konstrukcijų atsparumui ugniai, o šios įtakos tyrimams reikalingos skirtingų mokslo šakų žinios. Autoritetingi specialistai mano, jog, tiriant gaisrus, apanglėjimo greitis yra nepakankamai įvertinamas ir skiriama jam per mažai dėmesio. Mūsų šalyje naudojamose Rusijos mokslininkų rekomendacijose pateikiami apibendrinti medienos apanglėjimo greičiai, aptariama anglies sluoksnio matavimo specifika, teoriniais bei instrumentiniais metodais apskaičiuojama degimo trukmė, tačiau neįvardijama svarbių veiksnių įtaka.

A taxa na qual a madeira se converte em carvão é determinante para a avaliação da resistência ao fogo, pois o colapso de elementos estruturais de madeira e de seus derivados quando expostos ao fogo ocorre principalmente pela redução da área resistente da seção, devido à formação de carvão. A resistência ao fogo depende, portanto, das dimensões da seção transversal que é reduzida gradualmente ao ser exposta ao fogo. Vários países têm investido em pesquisas para a caracterização e determinação da taxa de carbonização com base em diferentes espécies. Nesse trabalho são apresentados dois modelos de taxa de carbonização para a madeira de Eucalyptus das espécies citriodora e grandis, de grande interesse para aplicação estrutural e plantadas no Brasil. Um para peças de madeira com pequena dimensão (17,2 cm x 17,2 cm x 6,0 cm) e outro para as vigas estruturais (0,16 cm x 0,26 cm x 2,00 m). A curva de aquecimento adotada foi a recomendada pela ASTM E-119. / The rate at which the wood converts in char is determinant to evaluate the wood fire endurance, because the failure of wooden structural elements and its composites exposed to fire occurs through reduction of cross section. The fire resistance depends on cross sections dimensions that are gradually reduced when exposed to fire. Several countries have invested in research to determine the wood charring used for building construction that result in the establishment of values to different species. This work presents two charring rate models for citriodora and grandis species of Eucalyptus, that presents structural interests in assemblies in Brazil. One model for small pieces (17,2 cm x 17,2 cm x 6,0 cm) and the other using structural beam ( 0,16 cm x 0,26 cm x 2,00 m). The standard temperature x time curve was ASTM E-119.

Daugelyje šalių mažo aukštingumo namų statybai gaminamoms įvairioms konstrukcijoms (stogų laikančiosioms konstrukcijoms, sienoms, sijoms, kolonoms ir kt.) dažnai naudojama mediena. Kilus gaisrui tokiuose pastatuose, labiausiai iš visų degimo požymių yra pastebimas medžio detalių (konstrukcijos elementų) apanglėjimas. Gaisro tyrinėtojams ypač aktualu susieti šį požymį su tam tikrais svarbiais gaisro poveikiais, pvz., jo trukme ar emperatūra, kad būtų galima nustatyti tikslią gaisro kilimo vietą (židinį) bei kilimo būdą (priežastį). Gaisro dinamika apsunkina medienos degimo trukmės nustatymo tikslumą, nes medinėje konstrukcijoje vyksta daug papildomų fizikinių-cheminių procesų. Šie procesai daro didelę įtaką konstrukcijų atsparumui ugniai, o šios įtakos tyrimams reikalingos skirtingų mokslo šakų žinios. Autoritetingi specialistai mano, jog, tiriant gaisrus, apanglėjimo greitis yra nepakankamai įvertinamas ir jam skiriama per mažai dėmesio. Lietuvoje naudojamose mokslininkų rekomendacijose [1-10] pateikiami apibendrinti medienos apanglėjimo greičiai, aptariama anglies sluoksnio matavimo specifika, teoriniais bei instrumentiniais metodais apskaičiuojama degimo trukmė, tačiau neįvardijama svarbių veiksnių įtaka. / 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... [to full text]

The current Swedish building code (Boverkets Byggregler, BBR) is very strict regarding fire-safety in high-rise timber structures because of the heightened risk of fast flame spread or structural failure in case of fire. Fire safety solutions, that are used in timber structures must therefore be optimal to contain flames from spreading in the event of fire. The current building code requires that load-bearing elements must withhold their load-bearing capacity for 60 minutes under fire. The purpose of this study was to research the effect that different fire-retardant surface treatments, have on fire protection of a load bearing, laminated timber element. Thereafter, a short analysis was made on the environmental impact of the fire-retardant surface-treatments in question and finally, a cost analysis and comparison were conducted with regard to different fire-safety solutions such as fire-resistant gypsum board and a combination of fire-resistant gypsum board and stone-wool. The methods used in this study are a combination of theoretical reviews and theoretical calculations. A theoretical review was conducted in order to collect the information needed to understand the behavior of timber under fire, the impact of fire-resistant surface treatments on fire protection, and the environmental impact of the actual surface treatments. Therefore, a series of theoretical calculations were made in accordance with European standards (Eurocodes) in order to present the impact in numbers. The calculations made were concerning a laminated timber beam with the dimensions of 145 x 450 x 6000 [mm] and took into account the remaining cross-section of the timber element under various timestamps during fire with regard to fire-stage, charring-rate, and fire coating. The results of this study indicate that the moment-capacity and shear-capacity of an untreated beam decrease constantly under fire and does not fulfill the requirements of the Swedish building code. Thereafter, in case that the same timber beam is fire-treated with a fire-retardant surface treatment. The moment-capacity is observed to increase in the first stage of fire, were the fire-protection of the surface-retardant treatment is still in action. Therefore, after fire-protection ceases, the moment-capacity of the timber beam is calculated to decrease in different rates with regard to fire-stage. The shear capacity of the treated beam is calculated to decrease under fire with a time-displacement of 30 & 60 minutes in comparison to the untreated element. The conclusions are that the studied surface treated timber beam and the actual fire treatments fulfill the requirements of the Swedish building code. Have insignificant environmental impact and are in comparison to other solutions cheaper.