Behaviour of fire-damaged engineered timber beams

Recently in Canada, the national building code has been amended to include mid-rise engineered timber buildings. The code also contains an allowance for Alternative Solutions, in which taller and more complex engineered timber structures may be built with sufficient research and proof of performance. For sustainable material use in infrastructure, an environmentally conscious population is motivating the employment of new engineered timber constructions. The purpose of this study is to investigate the behaviour of timber members, specifically glulam, before and after fire damage to inform future testing of large-scale engineered timber building systems. The experiments provide valuable data with regards to the post-fire performance and resiliency of mass timber. A novel Digital Image Correlation (DIC) technique using high-resolution imagery for deformation measurement through pixel movement was used for the first time, to the knowledge of the authors, in pre- and post-fire coupon specimens. The DIC analysis proved to be accurate in introductory tests on timber coupons post-heating, with the maximum difference from the traditional instrumentation being within acceptable tolerances in a separate calibration test. The accuracy decreased in the charred coupon tests, where significant scatter in strain measurement was observed, indicating possible refinement of the technology being necessary. In both coupon sets, the unburned members were recorded to have strength 18% higher than their burned counterparts. This suggests that complex failure modes occurred within the charred specimens which caused a premature failure which is investigated herein. Overall, both burned specimens exhibited significant resiliency to a severe fire exposure