The inherent nature of structural timber components to be charred slowly and at a predictable rate makes solid wood systems capable of maintaining significant structural capacity for extended periods of time when exposed to fire. Solid systems such as cross-laminated wood (CLT), glulam (GLT), nail-laminated timber (NLT) and dowel laminated timber (DLT) have proven that they can provide excellent fire resistance, often comparable to that of typical non-combustible heavy structures.
To facilitate greater acceptance of solid wood systems in international building codes, many topics still need to be studied. This session will cover the most recent topics related to fire safety for medium- and high-rise buildings.
Moderator : Christian Dagenais
Performance based design for multi-story timber structures in fire – Statistics and a Design Example
Speaker: Daniel Brandon, RISE, Sweden
Rapid development of technologies, changes in regulations and an increased focus on sustainability, among other things, have led to an increased use of timber as a structural material for complex and tall buildings. However, due to the combustibility of wood, the fire safety of such structures is routinely debated. This presentation provides an objective perspective by briefly discussing available statistics on fire damage in modern multi-storey timber buildings. Furthermore, some fires in multi-storey buildings with timber structures generating a great deal of damage were identified from a U.S. database and analyzed. Based on this analysis, design recommendations for tall timber buildings were developed and tested using a full-scale experimental case study. The experiment was conducted on a two-storey CLT building, which was designed using a performance-based approach. The performance criteria that the structure was designed against were:
– preventing fire from spreading to neighbouring compartments;
– avoiding sustained, fully developed fires and, instead, ensuring that a fire would decay for a significant period once the combustible content of the compartment, such as furniture, burns out.
Despite the presence of a significant amount of exposed CLT in the ignited compartment, the use of untreated timber and combustible PUR insulation in the facade, the fire did not spread to the upper floor of the structure. The fire decayed towards the end of the test, but did not extinguish by itself during the 2+ hour test. Although it can be stated that the criteria of the performance-based design approach were met, the performance of the structure would have improved if high-fire performance adhesives were used. The North American ANSI/APA PRG 320 (2018) requires the use of such adhesives in CLT. Work regarding European standardization for such adhesives is ongoing.
Future facade testing in Europe
Speaker: David Lange, University of Queensland, Australia
As the external envelope of a building, the facade is a key element for a fire safety strategy of a building. If a suitable system is properly implemented, it prevents the external spread of fire vertically and horizontally throughout a building, a key element when designing a high-rise building for fire resistance. Even prior to the Grenfell Tower fire in London in June 2017 which demonstrated the importance of this, representatives of some of Europe’s testing laboratories were already engaged in a project sponsored by the European Commission to develop a proposal for a harmonized testing and classification standard for facades in Europe. At the same time, jurisdictions in Australia were dealing with the fallout from facade fires in that country. This led to fundamental research on the performance of facade materials, as well as the introduction of new regulations in various states in Australia and motivated a drive for significantly higher fire safety standards.
This presentation provides a summary of the proposed testing standard for Europe. Given the introspection and scrutiny that fire engineering has been undergoing since 2017, the presentation goes on to discuss the need for better performance-related data in fire safety engineering as a supplement to the results of pass/fail, or classification based, fire testing.
Fire Fighting and Wood Structures
Speaker: Jan Smolka, Czech Fire Protection Association – Majaczech, Czech Republic
The modern production of engineered wooden materials such as glued-laminated timber and cross-laminated timber provides new opportunities in building of larger and higher structures as well as new methods of building light-weight structures with traditional materials. These advantages also require increased attention to potential risks in case of fire. New types of buildings with sophisticated structures allow hidden fire to spread in attics and void spaces. Flammable building material can participate in burning and lose its strength during a fire or firefighting attacks. These aspects should be considered during the construction of new buildings, especially with the presence of people. Understanding these aspects and sharing experience between fire engineers and firefighters can increase awareness of potential risks and determine adequate protection and dimensions for fire resistance and protection.
Christian Dagenais works as a senior scientist at FPInnovations where his main research topics are fire performance of wood structures, performance-based fire design, fire modelling, and fire safety engineering. He has been involved in various performance-based fire designs for wood construction of buildings that are otherwise required to be of non-combustible construction. He is the author of various technical publications and test reports related to the performance of wood components and buildings during fire. Dr. Dagenais actively participates in Codes & Standards technical committees, such as those related to fire testing, fire safety engineering and engineering design in wood for the ULC, ASTM and CSA standards. He is currently the Chair of the ISO TC 92 Canadian Mirror Committee on Fire Safety, and Head of the Canadian delegation at its SC4 Subcommittee, responsible for developing international standards on fire safety engineering. He participates in many overseas standards activities related to Building and Fire Codes, namely with the U.S., Australia, China and Japan. Lastly, he is a visiting professor at Université Laval where he teaches a full course on fire safety in buildings and supervises graduate students. Dr. Dagenais is a member of OIQ, CSCE and SFPE.
Daniel Brandon works as a researcher at Research Institutes of Sweden – Fire Research. He has a Ph.D. degree from the University of Bath in the UK, where he studied the behaviour of timber connections in fire and ambient conditions. He is currently leading national and international research projects on fire safety in timber buildings. He is also a Swedish delegate on the Eurocode CEN SC5 committee, dealing with the revision of the European standardization for Structural Fire Design of timber structures. Recently, Dr. Brandon received the Foundation Medal for outstanding research from the NFPA, the Howard Medal (a best-paper-award) from the Institution of Civil Engineers, and the L.J. Markwardt Award from the Forest Products Society.
Jan Smolka has an international and interdisciplinary background in fire safety. He is a formal firefighter with bachelor’s and master’s degrees and is currently continuing a doctorate in fire science in order to understand all aspects of fire prevention, resiliency and repression. Within the area of fire safety and risk management, he is experienced in firefighting, fire dynamics, designing fire safety plans, building protection, creating guidelines and training on the national and international levels. He was also an active member of COST Action FP1404, for which he led a task group focused on fighting fires in bio-based buildings.
He is currently a researcher at VSB-Technical University of Ostrava and Occupational Safety Research Institute under the Czech Ministry of Environment. To improve prevention and awareness of safety in Europe and the Czech Republic, Mr. Smolka runs the Czech Fire Protection Association – Majaczech as a member of CFPA-Europe where he leads projects such as fire hazard and risk assessments for industry. In a free time, he trains firefighters and promotes fire safety to the general public.