1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 61

1985 Ed.]

Building (Construction) Regulations

[CAP. 123

B 61

[Subsidiary]

Provided that in no case shall the maximum flexural stress in extreme fibres of the cased section exceed either-

(i) 14 times the maximum permissible stress on the uncased section of that beam or girder; or

(ii) that specified in Table XXIII.

whichever is the lesser stress.

TABLE XXIII

Maximum flexural stresses in extreme fibres of the cased section of a beam or girder

1

MPa

1.

Steel complying with the appropriate provisions of BS 4360: 1972-

(a) beams or girders other than plate/girders (b) plate girders

150

145

2.

High yield stress structural steel complying with the appropriate provisions of BS 4360: 1972--

(u) beams and girders, other than plate girders-

(i) material not more than 25 mm thick

310

(ii) material more than 25 mm thick

190

(b) plate girders-

(i) material not more than 25 mm thick

200

(ii) material more than 25 mm thick

185

L.N. 394/76.

98. (1) The permissible ratio of effective column or strut length (/) to least radius of gyration (k) shall not exceed the following values:

(a) for any member carrying loads resulting from dead

and imposed loads

Stresses in columns and

struts.

180

(b) for any member carrying loads resulting from wind forces only, provided the deformation of such mem- ber does not adversely affect the stress in any part of the structure carrying loads resulting from dead and imposed loads...

250

(c) for any member normally acting as a tie in a roof truss but subject to possible reversal of stress due to the action of wind suction

350

(2) Subject to the provisions of paragraph (3) and of regula- tions 99 and 100 the axial stress on column and struts of steel shall not exceed the maximum permissible axial stress specified in Table XXIV for the ratio Ik specified in that Table.