Travelling fires with exposed CLT surface. Planning of full-scale test

The use of engineered wood products, like glue laminated timber and cross laminated timber (CLT) has increased massively over the last years. The increased popularity is caused by the many advantages of building with wood, like the possibility of prefabrication, the low carbon footprint, the easy handling and mounting of wood, and its aesthetic look. With the increased popularity, CLT is now used in large compartment buildings, public buildings and office buildings. However, most experiments studying the fire performance of CLT buildings have been carried out on relatively small compartments with small window openings, resulting in ventilation controlled fires [1-3]. Most modern buildings have large open-plan spaces and large window openings to allow for natural light. A fire in this type of compartment is likely to become fuel controlled, and not ventilation controlled. It can also travel through the room. Fire dynamics of large open-plan spaces with large window openings is often characterized as travelling fires [4]. Travelling fires are recognized with a steady propagation and burnout of the fire through the room. Several full-scale travelling fires have been conducted over the last years, but only in compartments with non-combustible surroundings [5]. However, recently tests have also been carried out with a CLT ceiling. These tests have provided new knowledge about how an exposed CLT surface affects the fire dynamic and fire spread rate. In a 1/8-scale test, Nothard et al.[6] studied the effect of having the ceiling exposed, and reported a more rapid fire spread with an exposed ceiling. In the CodeRed#01 test [7], a fire test was conducted in a 380 m2 combustible compartment with a CLT-ceiling. Initially, the fire spread slowly along a wood crib. But, after the fire plume hit the ceiling, the fire spread rapidly across the exposed ceiling. The intense burning of the ceiling then caused radiation down to the woodcrib, and caused the fire to spread across the entire 174 m2 wood crib area within 5-6 minutes. The fire developed faster than what is considered an ultra-fast fire spread. In the X-ONE fire test [8], which was an almost identical test, but with no exposed ceiling, the fire spread across the room in about 25 minutes. Through the few tests performed with a combustible ceiling, it is evident that there is a need for more knowledge on how different exposed CLT surfaces affects the fire spread and fire safety in large compartments. How fast a fire spreads is highly relevant for several aspects within fire safety, like: Available time for people to evacuate safely, the size of the fire when the fire brigade enters the building, extinguishing tactics etc. In order to better understand how an exposed surface affects the fire spread in a large CLT compartment with large window openings, two full-scale tests will be carried out in Autumn 2022 in the FRIC-research centre.publishedVersio

Experimental Study of the Charring of I-Joists and Recession of Combustible Insulation in Light Timber Frame Assemblies with Comparison to Eurocode 5

Design models are commonly used in fire safety design of light timber frame assemblies. Parameters for use in the models are available for rectangular members with mineral wool, wood fibre or cellulose insulation and for assemblies with I-joists and mineral wool. For assemblies where I-joists and combustible insulations are combined, design parameters are missing. Five fire experiments with two Ijoist types and four combustible insulation products have been conducted. The aim was to study charring of I-joist flanges and recession rates of combustible insulations and in addition, to compare their behaviour to the new and existing models of Eurocode 5. Charring rates for the flanges were 0.40–0.76 mm/min and 0.54–1.72 mm/min for the protected and post-protected phase, respectively. Rates decreased with increasing flange size. Charring rates for flanges of solid wood and LVL were comparable. The results show that lateral charring of I-joist flanges can be significant in the protected phase. The tested insulation products showed a lower recession rate than values reported for glass wool insulation, with a more pronounced difference for wood fibre and cellulose insulations. The low recession rates compared to previously reported generic values can possibly be explained by better product-specific properties, negligible shrinking and slightly different test set-up. The insulation stayed well in place after gypsum board fall-off and best-practice for keeping the insulation in place is given. The results, completed with future loaded full-scale tests, can give basis for further development of design models for assemblies with I-joists and combustible insulations.publishedVersio

Large-scale fire experiments in a cross-laminated timber compartment with an adjacent corridor – Partly and fully protected with a water sprinkler system

Two fire experiments have been conducted to study sprinkler system extinguishing performance in a compartment (13 m2) with an adjacent corridor (12 m2), both with exposed cross-laminated timber (CLT). Four nozzles were installed in the corridor and two in the compartment. In Experiment 1, the sprinkler system was fully functional and successfully controlled a concealed fire. In Experiment 2, nozzles in the compartment were disconnected, while the corridor nozzles were operative, giving flashover after 5 min with large flames emerging into the corridor, rapidly worsening evacuation conditions. Despite four activated nozzles in the corridor, the temperatures remained high, and flames spread through the corridor along the CLT ceiling and the upper parts of the wall, an area that was not effectively protected by the nozzles. After flashover, the compartment temperatures remained stable at ∼1000 °C until experiment termination at 96 min. This continued fire in the compartment can be explained by water from the corridor sprinklers not reaching this area, extensive radiative feedback by the CLT surfaces and delamination of CLT elements of the 20 mm layers. The charring rate was ≥1.1 mm/min for large parts of the exposed CLT wall and ceiling in the compartment during the fire.publishedVersio

Fire spread in a large compartment with exposed cross-laminated timber and open ventilation conditions: #FRIC-01 – Exposed ceiling

Exposing cross-laminated timber (CLT) structures in buildings is increasingly popular in modern buildings. However, large timber surfaces, window facades, and different geometries can change the fire dynamics in a compartment. The effect of those parameters, therefore, needs to be studied. Two large-scale CLT compartment fire experiments (95 m2) have consequently been performed. The experiments were designed to represent a modern office building with an open-plan space and large window openings. In this experiment, #FRIC-01, the ceiling was exposed. The wood crib fire developed slowly and travelled approximately 1.5 m before the ceiling ignited at 32.5 min. Thereafter the fire spread rapidly across the ceiling and wood crib before it shortly after retracted. Three such cycles of rapid spread followed by a retraction occurred within 13 min, whereby the wood crib fire grew larger for each cycle. After the flames extended through the compartment for the fourth time, the fire remained fully developed. After a short period of intense burning, the CLT self-extinguished while the wood crib fire was still burning. The compartment withstood full burnout, and no reignition occurred despite some delamination and using an adhesive that lacks a demonstrated resistance against glue-line integrity failure.publishedVersio

En vurdering av effekten til slokkesprayer på det norske markedet

Kravene som stilles til slokkesprayer (en type supplerende brannslokningsutstyr) er tydelige når det gjelder merking, men uklare med hensyn til slokkeeffekt. SP Fire Research har på oppdrag for Direktoratet for samfunnssikkerhet og beredskap (DSB), testet 11 slokkesprayer for å undersøke hvor god slokkeeffekten er, og hvor godt merket de er. Resultatene fra testene viser at de aller fleste slokkesprayene ikke tilfredsstiller krav til slokkeeffekt som oppstilles av den britiske standarden BS 6165:2002 og den kommende europeiske standarden prEN 16856:2015, som omfatter slike produkter.   De beste produktene viste imidlertid en relativt god slokkeeffekt, og kan være et godt supplement til annet brannslokningsutstyr for å slokke en brann i en tidlig fase.

En vurdering av effekten til slokkesprayer på det norske markedet

Kravene som stilles til slokkesprayer (en type supplerende brannslokningsutstyr) er tydelige når det gjelder merking, men uklare med hensyn til slokkeeffekt. SP Fire Research har på oppdrag for Direktoratet for samfunnssikkerhet og beredskap (DSB), testet 11 slokkesprayer for å undersøke hvor god slokkeeffekten er, og hvor godt merket de er. Resultatene fra testene viser at de aller fleste slokkesprayene ikke tilfredsstiller krav til slokkeeffekt som oppstilles av den britiske standarden BS 6165:2002 og den kommende europeiske standarden prEN 16856:2015, som omfatter slike produkter.   De beste produktene viste imidlertid en relativt god slokkeeffekt, og kan være et godt supplement til annet brannslokningsutstyr for å slokke en brann i en tidlig fase.

Brannsikkerhet og alternative energibærere : Gasskjøretøy i tunneler og parkeringskjellere

Denne litteraturstudien av brann- og eksplosjonsrisiko for gasskjøretøy i tunneler og parkeringskjellere er en videreføring av et tidligere prosjekt utført ved SP Fire Research, Brannsikkerhet og alternative energibærere: El- og gasskjøretøy i innelukkede rom. I forhold til det tidligere prosjektet, bidrar denne rapporten med referanser til nyere litteratur og fokuserer på kjøretøy med CNG (komprimert naturgass) og hydrogen. Konsekvenser ved en eksplosjon i gasskjøretøy, norsk regelverk og forslag til sannsynlighetsreduserende tiltak diskuteres. Hovedkilden til denne litteraturstudien er en svensk rapport fra 2016. Basert på denne studien foreslås det at videre arbeid i første omgang fokuserer på hvilken effekt en hydrogentank- og en hydrogenskyeksplosjon vil ha på typiske, norske parkeringskjellere

FRIC webinar: Large-scale compartment experiments with exposed Cross-Laminated Timber (CLT).

ID nummer: FRIC webinar D3.2-2023.04</p

FRIC webinar: Large-scale compartment experiments with exposed Cross-Laminated Timber (CLT).

ID nummer: FRIC webinar D3.2-2023.04</p

Fullskala branntest av elbil

Norge og Grenland Energy, gjennomført to fullskala branntester av elbiler av merke Tata Indica GLX. Batteriet i bilene var et 26 kWh Li-ion batteri med en katode bestående av nikkel, magnesium og kobolt (NMC-katode).  I test 1 ble en elbil sluppet i fritt fall fra en høyde på 20 meter, for å simulere en kraftig kollisjon. Umiddelbart etter sammenstøtet begynte det å ryke kraftig fra batteriet. Etter  ca. 7 minutter begynte bilen å brenne med synlige flammer. Bilen fikk deretter brenne fritt. Etter 2,5 timer ble temperaturen målt mellom 310 og 540 °C på ulike deler av batteripakken. Bilen var da fullstendig utbrent. Testen viser at en elbil som blir utsatt for en kraftig kollisjon kan begynne å brenne.   I test 2 var målet å antenne batteripakken ved å bruke en ekstern varmekilde, for deretter  å måle hvor mye slokkevann som krevdes for å slokke brannen. Batteriet ble oppvarmet av en propanbrenner fra undersiden av bilen. Etter ca. 10 minutter begynte bilen å brenne med synlige flammer. Det ble gjennomført to slokkeforsøk under brannen. Brannen reantente etter første slokkeforsøk, men ble fullstendig slokket i andre forsøk. Til tross for den eksterne oppvarmingen av batteriet, og at bilen var overtent i en lengre periode, begynte det ikke å brenne i batteripakken. Brannen kunne dermed  slokkes med samme innsatsmetode og tidsforbruk som en brann i en konvensjonell bensin-/dieselbil