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.
Page 55
Page 56
1985 Ed.]
Building (Construction) Regulations
[CAP. 123
B 55
[Subsidiary]
(2) In a post or strut the ratio of effective length (/) 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
2
5
6
7
8
Least
Least
Least
Least
radius of
lateral
radius of
lateral
B
gyration
dimension
gyration
dimension
(UK)
(UK)
(k)
(K)
28868820
0
7.0
5.5
80
23
4.8
3.9
10
3
6.7
5.4
90
26
4.2
3.4
6.6
5.3
100
29
3.6
2.9
30
9
6.5 5.2
120
35
2.8
2.2
40
11
6.3
5.0
140
40
2.1
1.7
50
14
6.0
4.8
160
46
1.6
1.3
17
5.7
4.5
180
52
1.4
L.1
70
20
5.3
4.3
200
58
1.1
0.9
L.N. 294/76.
Note: The maximum permissible compressive stress for intermediate values of ik or #b 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.
1
TABLE XIX
Effective length of posts and struts
2
Type of post or strut
Properly restrained at both ends in position
and direction
Properly restrained at both ends in position
and at I end in direction
Properly restrained at both ends in position
but not in direction
Properly restrained at I end in position and direction and at the other end partially restrained in direction but not in position Properly restrained at 1 end in position and direction but not restrained at the other end
Effective length (L= length of post or strut between centres or restraining members)
0.7 L
0.85 L
L
1.5 L
2.0 L
Note: 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.
Page 55Page 56
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