1964_BUILDING_(CONSTRUCTION)_REGULATIONS — Page 59

1985 Ed.]

Building (Construction) Regulations

[CAP. 123

B 59

[Subsidiary]

I

2

Mild steel complying with the appropriate provisions

of BS

:

High yield stress

structural steel complying with the appropriate provisions of BS 4360: 1972

For material

not exceeding

35 mm in thickness or

diameter

4

For material exceeding 15 mm in thickness or diameter

Part of structure and kind of stress

4360: 1973

4.

For parts in bearing-

(a) bearing stress steel to steel on net area

of contact

185

260

230

(b) on shop rivets and turned bolts

185

260

230

(c) on field rivets

150

210

190

(d) on black bolts

120

5.

For welded connexions-

(a) tensile stress in butt welds

1x f

(b) compressive stress in butt welds

...

(c) shear stress in butt welds

(d) stress in fillet welds

1xf

Note: l is the length between effective lateral supports.

k

is the least radius of gyration of the beam or girder section.

d is the clear distances between flange angles (or flange plates where there are no flange angles) or web stiffeners, whichever is the lesser.

/ is the thickness of the web.

ft, fc and fs are the maximum permissible tensile, compressive and shear stresses, respectively; in the parent metal or in the weld metal, whichever is the lesser.

(3) Subject to paragraph (4), where a beam or girder is of symmetrical section, the maximum permissible stresses specified in item 2(b) of Table XX may be increased by the percentage specified in Table XXI for the ratio (k1/k2) of the greatest to the least radius of gyration of the section of that beam or girder.

1

TABLE XXI

Percentage increase for shape factor

k1/k2

5.0

4.5

4.0

3.5 or less

...

Percentage increase

5.0

15.0

30.0

50.0

Note: (1) k1 is the greatest radius of gyration of the beam or girder section.

(2) The percentage increase for intermediate values of the ratio k1/k2 shall

be obtained by linear interpolation between the 2 nearest values.

XX II