Building Construction Handbook, Eighth Edition

Although generally non-load bearing, timber stud partitions may
carry some of the load from the floor and roof structure. In these
situations the vertical studs are considered struts.

Example ~ using the stud frame dimensions shown on the previous
page, with each stud (strut) supporting a 5 kN load.

2500

1250

Section Elevation

5kN(5000 N)

95x45

struts in

sw strength

class C18

Effective length

of struts as

shown on page

548. Position
     fixed at both
     ends, the
     effective length
     is the actual
     buckling length.
     tendency

1250

Slenderness ratio (SR) of section = Effective length...breadth
On the partition face = 1250...45 = 27.8
At right angles to the face = 2500...95 = 26.3
Timber of strength classification C18 (see pages 114 and 115) has the
following properties:
Modulus of elasticity = 6000 N/mm^2
Grade stress in compression parallel to the grain = 7.1 N/mm^2
Grade stress ratio = 6000...7.1 = 845

See table adapted from BS 5268-2 on page 161. By coordinating the
SR of 27.8 (greater value) with a grade stress ratio of 845, a
figure of 0.4 is obtained by interpolation.

Allowable applied stress is 7.1 N/mm^2 ¾0.4 = 2.84 N/mm^2
Applied stress = axial load...strut section area
= 5000 N...(95 mm¾45 mm) = 1.17 N/mm^2
1.17 N/mm^2 is well within the allowable stress of 2.84 N/mm^2
therefore 95 mm¾45 mm struts are adequate.

See pages 159 to 161 for an application to dead shoring. Struts in
trusses and lattice frames can also be designed using the same
principles.

Timber Stud/Strut Design