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