Determination of charring thickness of wood by residual strength analysis

This study was conducted to propose an accurate measurement method of charred thickness in structural glued laminated timber (glulam) exposed standardized fire temperature conditions for evaluation the resistance Japanese larch (Larix kaempferi) glulam. The compressive strength test piece collected from glulam two hours analyzed. results showed that there residual 14% boundary area between sound and part. Therefore, part should be calculated as approximately 4.5 mm less than what is measured visually. cell wall sound-, boundary-, charred-part high observed under a microscope. Higher resulted thinner tracheid wall, radial tissue broken down. transformation these microstructures progressed gradually until full carbonization wood occurred. Based on tests microscopic observation specimens temperature, current visual assessment safe terms aspect but not efficient utilization point view due exception load carrying member.