1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 54

B 54

[Subsidiary]

CAP. 123] Building (Construction) Regulations

[1985 Ed.

(2) The mean value of the modulus of elasticity shall only be used for rafters and floor and ceiling joists and, in all other cases, the minimum value of the modulus of elasticity shall be used.

(3) Where the direction of the load is inclined to the direction of the member, the permissible compressive stress for the inclined surface shall be determined by the formula:

Chi = Chi

Ch sin2θ + Chr cos2θ

where

Ch is the permissible compressive stress parallel to the grain,

Chi is the permissible compressive stress for the inclined surface.

Chr is the permissible compressive stress perpendicular to the grain, and

θ is the angle between the direction of the load and the direction of the grain.

(4) The shear strength at square cornered notches at the ends of a flexural member shall be calculated by using the effective depth (d) shown in the following figure:

T

Maximum permissible stresses for posts and struts.

Beam notched at end

and also a permissible shear stress equal to that specified in Table XVII multiplied by the reduction factor K where--

K = effective depth (de) / total depth (d)

(5) For the purpose of this regulation, adequate lateral restraint to a flexural member against winding or buckling shall be deemed to have been provided if the distance between the lateral restraints does not exceed 50 times the breadth of the member.

89. (1) Subject to regulation 92, the compressive stress in the direction of the grain of a post or strut shall not exceed the maximum permissible stress specified in Table XVIII for the ratio of effective length (l) to the least radius of gyration (k) (or the least lateral dimension (b) in respect of solid members of rectangular cross-section only) specified in that Table,