Smoke Hazards of Tall Timber Buildings with New Products

Abstract

Timber buildings can now stand very tall using new products. As timber materials are expected to be easily ignitable, the fire hazard of timber is a concern. Charring of the timber surface would maintain structural stability, but would also be accompanied by smoke. Although treating timber products with fire retardants would delay the ignition time under low radiative heat flux, toxic combustion products and unburnt fuel would be emitted immediately upon burning. More smoke and higher toxic gas concentrations such as carbon monoxide would be given off upon burning some fire retardants under high flashover heat fluxes. Due to the fast upward movement of smoke under stack effect, spreading of toxic smoke in tall timber buildings would lead to a hazardous environment. Engineered timber consists of derivative timber products. New engineered timber products are manufactured with advanced technology and design, including cross-laminated-timber (CLT), laminated veneer lumber (LVL) and glue-laminated timber (Glulam). The fire behaviour of timber products has been studied for several decades. However, the smoke hazards of using new timber products in building construction should be monitored. The objective of this study is to inspire stakeholders in fire safety of timber buildings, inter alia smoke hazards, to use new timber products to build tall buildings.

Contemporary Fire Safety Engineering in Timber Structures: Challenges and Solutions

“…To date, the burning behavior of timber has been complex. The processes behind pyrolysis, ignition, and combustion are generally well understood [13], with good agreement in the fire science literature over a wide range of experimental conditions for crucial parameters such as critical heat flux for ignition (12 kW/m 2 ± 2 kW/m 2 ) and heat of combustion (17.5 MJ/kg ± 2.5 MJ/kg). These parameters are vital for evaluating the risks of using timber as a construction material [26].…”

“…Conversely, softwoods, such as spruce and pine, are easily ignited due to their porous, cellular structure, and they burn faster while releasing relatively more heat [39,50]. The fire behavior of timber structures is, among other factors, dependent on the fire behavior of timber, and many related studies have been reported [13]. Understanding these disparities aids in grasping the behavior of wood under fire conditions, thereby providing a scientific foundation for fire safety design.…”

“…Scholars have carried out a series of experimental studies and mechanistic research on the combustion characteristics of timber, as shown in Table 2. As shown in Table 2, Bartlett et al conducted a comprehensive review of timber fire dynamics [8,13,26]. The preliminary work's calculations for modeling heat and mass transfer in timber during fire were based on the model developed by Fredlund [53].…”

“…This challenge was evident in several fires in China, including the 2014 devastation of Yunnan's Shangri-La ancient town, the destruction in Guizhou's Jiujie Miao Village, and the 2023 Tongren ancient timber structures fire. These incidents emphasize the critical need for enhanced fire prevention and safety measures in timber construction practices [13,14]. Figure 1 illustrates the intense conflagration that ravaged Notre Dame de Paris Cathedral, a landmark of Gothic architecture [11].…”

“…As skyscraping timber structures represent a more sustainable future for urban development, their fire safety issues demand rigorous academic investigation and innovative, research-based solutions. A comprehensive review of literature specifically addressing the fire-related risks in timber structures is notably absent [8,13,[26][27][28]. This review is committed to systematically exploring the latest advancements in fire safety for timber structures, with the aim of addressing current challenges and forecasting future research trends.…”