Critical design condition, Xn

Check also on the flange strength -= 0.68

X1 Xmax condition, i.e.-must be less than 1


(if the ratio is 1 the lattice column profile must be changed)

2. Timber strength properties

Table 1.3, strength class C22 (BS EN 338:2003(E), Table 1)

Characteristic compression strength /c.0.k = 20N/mm2 parallel to the grain, /c.0 k i.e. the ratio is less than 1; therefore OK

Characteristic bending strength, /m.0.k

Fifth-percentile modulus of elasticity parallel to the grain, £0.os fm.0.k = 22 N/mm2 Eq,q5 = 6.7kN/mm2

3. Partial safety factors

Table 2.8 (UKNA to BS EN 1990:2002, Table NA.A1.2(B)) for the ULS

Permanent actions, yg Variable actions, yq Table 2.6 (UKNA to EC5, Table NA.3) Material factor for solid timber, ym 4. Actions

Characteristic bending moment about the z-z axis, Mk

Characteristic permanent axial action,

Characteristic medium-duration variable axial action, Qk

Design compressive axial action for the critical load combination, Nd

(Table 2.8, equation (c) using the unfavourable condition)

Design moment on the column about the z-z axis, Md

5. Modification factors

Factor for short-duration loading and service class 1, kmod.short (Table 2.4 (EC5, Table 3.1))

System strength factor, ksys - not relevant

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