Remember of some buckling lengths

a- Diagonal and vertical joined with lower compression chord:

Lout = 1.2 L if one of the 2 ends of the vertical and the diagonal is not

braced.

What braces a point?

(1) Purlin (2) Long. Bracing

(3) Tension in both members meeting at that point

Examples:

Calculate buckling lengths outside plan for lower chord, diagonals and

verticals for the given shapes.

1)

L1 = L2 = L3 = 3a L4 = L5 = 2a

D1 = D2 = 1.2L D3 = D4 = D5 = L (lower point

braced)

V1 = 1.2L V2 = V3 = V4 = V5 = L

2)

L1 = L2 =L3 = 3a L4 = L5 = 2a

D1 = D2 = 1.2L D3 = D4 = D5 = L (lower point

braced)

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V1 = V2 = 1.2L V3 = V4 = V5 = L

3)

LC1 = LC2 = 2a

L1 = L2 =L3 = L4 = 4a

DC1 = DC2 = 1.2L D1 = D2 = 1.2L D3 = D4 =

L

VC1 = L VC2 = 1.2L V1 = V2 =

1.2L V3 = V4 = L

4) L1 = L2 = 2a L3 = L4 = L5 = 3a

D1 = D3 = D4 = 1.2L

D2 = D5 = L V1 = V3 = V4 = 1.2L

V2 = V5 = L

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