Relationships between wood properties and fire performance of glulam columns made from six wood species commonly used in China

Abstract

Glued laminated timber stands as an increasingly favored engineered wood product in low-rise modern timber structures due to its commendable structural performance and carbon sequestration potential. Chinese standards presently fail to differentiate the effects of distinct wood species on the fire resistance of glulam. This study examined the charring rate and residual bearing capacity of glulam columns made from six commonly used wood species in China: poplar, Chinese fir, Douglas fir, hemlock, larch, and spruce. These materials exhibited densities ranging between 390 and 645 kg·m−³. ISO standard fire tests were conducted employing one- and two-adjacent-side fire exposures. Notably, the findings unveiled that high-density glulam columns demonstrated lower charring rates and slower rates of heat penetration. The two-adjacent-side fire configuration induced a corner effect, consequently amplifying the effective charring depth. The results showed a linear relationship between the ratio of diagonal to horizontal charring rate of the columns exposed to the two-adjacent-side fire and wood density. To enhance practical application, a formula was developed, employing the residual section method, to calculate the column's residual bearing capacity post two-adjacent-side fire exposure. This formula incorporates an adjustment depth to accommodate the corner effect, effectively mitigating the reduced wood strength within the pyrolysis zone.