- Author
-
Majamaa, J.
- Title
- Calculation Models of Wooden Beams Exposed to Fire.
- Coporate
- VTT-Technical Research Center of Finland, Espoo
- Report
-
VTT Research Notes 1282; Project PAL7003,
September 1991,
54 p.
- Keywords
-
wooden structures
|
beams
|
timber
|
construction
|
fire safety
|
structural members
|
elastic properties
|
temperature
|
moisture
|
failure
|
shear stress
- Identifiers
- fire resistance; beams (supports); bending stress; stiffness
- Abstract
- This study describes a time-to-failure calculation model for wooden beams under a standard fire exposure. The model is based on the linear theory of elasticity by taking the effect of temperature and moisture on the strength and stiffnes of the wood into account. The time-to-failure criterion is a tensile failure in a finger joing (a glu-lam beam) or in a knot. The bending and shear stress distributions in the non-charred wooden cross section are calculated analytically by dividing the cross section into several layers with different material properties. The bending moment and shear capacity are then calculated by summing the capacities of the layers. Finally, the calculation is compared with test results. Beams are assumed to be of rectangular cross section and exposed to fire on three or four sides. Some earlier calculation methods are briefly reviewed.