where ky — 0.5(1 + ^rel.y - 0.3) + A.^) kz — 0.5(1 + - 0.3) + A.^)

(EC5, equation (6.25)) (5.4a) (EC5, equation (6.26)) (5.4b)

(EC5, equation (6.27)) (5.5a) (EC5, equation (6.28)) (5.5b)

and pc has been derived from the analyses and applies to solid rectangular members compliant with the straightness limits given in Section 10 of EC5 (i.e. the deviation from straightness measured midway between supports should be less than or equal to member length/300 for timber members and less than or equal to member length/500 for LVL (and glulam) members) as well as the tolerance limits for member sizes. For these cases, equation (6.29) in EC5 states

— 0.1 for glued-laminated timber and LVL

From the above, the strength of the member at the design condition will be as follows,

Buckling strength about the y-y axis = kcy fc>o,d Buckling strength about the z-z axis = kc,z fc>0jd

where kc y and kc z are as defined in equation (5.4) and fc 0 d is the design compressive strength of the member parallel to the grain.

An alternative to evaluating kc>y and kc>z using equations (5.4)-(5.6) is to use tables set out in terms of the strength class of the timber and the slenderness ratio of the member. Slenderness ratio, X, has been used rather than relative slenderness ratio, A.rei,

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