1985 Ed.]
Building (Construction) Regulations
[CAP. 123
B 55
[Subsidiary]
(2) In a post or strut the ratio of effective length (l) to— (a) least radius of gyration (k), shall not exceed 200; or (b) least lateral dimension (h), shall not exceed 58.
(3) No post or strut shall be so notched as to reduce its dimensions below those found necessary by calculation.
TABLE XVIII
Maximum permissible compressive stresses in posts and struts in MPa
Ratio of effective length to Class of timber Ratio of effective length to- Class of timber Least radius of gyration (k) Least lateral dimension (h) 2 5 6 7 8 0 7.0 5.5 10 6.7 5.4 20 6.5 5.2 80 23 4.8 3.9 30 6.3 5.0 90 26 4.2 3.4 40 6.0 4.8 100 29 3.6 2.9 50 5.7 4.5 120 35 2.8 2.2 60 5.3 4.3 140 40 2.1 1.7 70 5.0 4.0 160 46 1.6 1.3 180 52 1.4 1.1 200 58 1.1 0.9L.N. 294/76.
Note: The maximum permissible compressive stress for intermediate values of l/k or l/h shall be obtained by interpolation between the 2 nearest stresses for the class of timber used.
90. For the purpose of regulation 89 the effective length of a post or strut shall be that specified in Table XIX for the type of post or strut specified in that Table.
Effective length of posts and struts.
TABLE XIX
Effective length of posts and struts
Type of post or strut Effective length (L= length of post or strut between centres or restraining members) Properly restrained at both ends in position and direction 0.7 L Properly restrained at both ends in position and at 1 end in direction 0.85 L Properly restrained at both ends in position but not in direction L Properly restrained at 1 end in position and direction and at the other end partially restrained in direction but not in position 1.5 L Properly restrained at 1 end in position and direction but not restrained at the other end 2.0 LNote: The effective length of a post or strut of a type not specified in this Table shall be determined to the satisfaction of the Building Authority.
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