Why may glue-laminated beams in Modern Type IV facilities fail when exposed to fire?

Why may glue-laminated beams in Modern Type IV facilities fail when exposed to fire?

• A. Unburned fire fuel may melt the laminate coating
• B. Heat may affect the glue holding the laminates together
• C. Higher exterior pressure may cause the laminate beams to fail
• D. Oxygen-rich fuel gases may warp the studs the beams are attached to

Answer: (B)

Heat exposure weakens the glue that bonds the laminations in a glue-laminated beam. When the adhesive softens or degrades, the bond between the layers fails, causing delamination and a loss of the beam’s structural capacity even if the wood itself hasn’t fully burned. Glulam relies on a strong internal bond between laminations, and once that bond is compromised, the beam can fail under load. The other ideas—coating melting, external pressure, or warping due to oxygen-rich gases—are not the primary mechanisms behind glulam beam failure in fire.

Heat exposure weakens the glue that bonds the laminations in a glue-laminated beam. When the adhesive softens or degrades, the bond between the layers fails, causing delamination and a loss of the beam’s structural capacity even if the wood itself hasn’t fully burned. Glulam relies on a strong internal bond between laminations, and once that bond is compromised, the beam can fail under load. The other ideas—coating melting, external pressure, or warping due to oxygen-rich gases—are not the primary mechanisms behind glulam beam failure in fire.