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
- 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