Slides for Lecture section B

B1-1 Cumulative probability of failure for a reference volume

B1-2 EC5 size factor for solid timber in bending or tension (solid line), related to theory (dashed line).

B1-3 Design of a double tapered beam.

B2-l Principal axes and principal planes in wood. For a small rectangular block taken out from the outer part of the tree trunk the rectangular coordinate system L,R,T, (b), can be defined.

B2-2 Stress-strain curves for clear wood loaded parallel to the grain (solid line) and perpendicular to the grain (dashed line) at a constant strain rate.

Typical values for softwood: ft,0 = 80 to 100 N/mm2, fc,0 = 40 to 50 N/mm2, E0 = 11000 to 15000 N/mm2.

B2-3 Compression failure at fc,0. Buckling of fibres. (Hoffmeyer, 1990). LW latewood, EW earlywood, AR armual rings, CC compression creases.