CIVL439/W00D476 Establish Design Properties Size Effects UTS MPA) G1>03>01 Size Effects Significance of Size Effects Tension Parallel a Modulus of Rupture MOR Shearr Weibull Weakest Link Time Dependent Behaviour of 案 案 10 装 15CIVL439/WOOD476 15 Establish Design Properties 0.6 0.8 1.0 Probability 0.0 0.2 0.4 0 20 40 60 80 UTS (MPa) Cumulative P Size Effects P1 P1 P2 P2 P P3 3 σ1 > σ2 > σ3 Size Effects P1 P4 P5 P /2 5/2 P2/2 P2/2 P6 P /2 6 P /2 3/2 P3/2 1.55m 3m σ1 > σ2 > σ3; σ4 > σ5 > σ6 σ1 > σ4; σ2 > σ5; σ3 > σ6 Tension Parallel σt par ** Tension Perpendicular σt perp *** Modulus of Rupture MOR ** Significance of Size Effects Compression Parallel σc par * Compression Perpendicular σc perp * Shear τ ∗∗∗ CDF Weibull Weakest Link 1 N σ Tensile Strength C Assumptions: 1) the strength of each element is described by the same cumulative distribution function 2) the strengths of the elements are statistically independent t = 1 Time Dependent Behaviour of Wood t = 10 t = 100 Creep & creep Rupture