In wood trusses, which component is the primary weak point that can warp and fail under heat?

In wood trusses, which component is the primary weak point that can warp and fail under heat?

• A. Gusset plate
• B. Top Chord
• C. Web
• D. Nails

Answer: (A)

Joint integrity under fire is dominated by the connection that binds the truss together. The gusset plate is the critical connector that ties the top and bottom chords to the web members and transfers shear forces through the joint. When heat enters the scene, metal plates are the first element to respond: they can warp, buckle, or lose their grip on the nails and fasteners long before the wood itself losses all strength. Once the plate deforms, the joint can no longer transfer forces properly, allowing members to separate and the truss to fail. The wood members may burn or lose stiffness, but without a solid plate holding the joint, the collapse mechanism is set in motion. Nails and wood are important, but the gusset plate’s deformation under heat is what initiates the failure of the truss joint.

Joint integrity under fire is dominated by the connection that binds the truss together. The gusset plate is the critical connector that ties the top and bottom chords to the web members and transfers shear forces through the joint. When heat enters the scene, metal plates are the first element to respond: they can warp, buckle, or lose their grip on the nails and fasteners long before the wood itself losses all strength. Once the plate deforms, the joint can no longer transfer forces properly, allowing members to separate and the truss to fail. The wood members may burn or lose stiffness, but without a solid plate holding the joint, the collapse mechanism is set in motion. Nails and wood are important, but the gusset plate’s deformation under heat is what initiates the failure of the truss joint.