B 56
[Subsidiary]
Maximum deflexion.
Stresses due to
imposed load on pitched roof.
Combined bending and axial stresses.
CAP. 123] Building (Construction) Regulations
[1985 Ed.
91. The calculated deflexion of any joist or binder shall not exceed 1/360 of its length.
92. (1) The maximum permissible stresses specified in this Part may be increased by 25 per cent for members forming part of the roof construction of a pitched roof when the calculations are based on all loads including imposed load.
(2) No increase in the maximum permissible stresses specified in this Part shall be allowed when the calculations are based on all loads other than imposed load.
93. Members subject to combined bending and axial compression shall be so proportioned that the quantities
f/F + fb/Fb
shall not exceed-
(a) unity, for members with a ratio of effective length to least radius of gyration not exceeding 20; and
(b) 0.9, for members where that ratio exceeds 20,
where- f = axial compressive stress,
Joints and connexions.
Cleaning and protection against corrosion.
F = maximum permissible compressive stress in posts and struts,
fb = maximum compressive stress due to bending; and
Fb = maximum permissible compressive flexural stress in extreme fibres of beams.
94. (1) All framing, tenoning, spiking or nailing, bolting, strapping and other jointing shall be so designed as safely to transmit the load and stresses to which it will be subjected and the execution of all such jointing shall be to the satisfaction of the Building Authority.
(2) Where bolts are used, adequate plates or washers shall be used to preserve the grain of the timber from crushing.
PART XI
STRUCTURAL USE OF STEEL
95. (1) Structural steel shall be cleaned of loose scale and rust and, except where it is to be solidly encased with concrete, brickwork or other similar non-combustible material, shall be either-
(a) thoroughly coated with at least 2 coats of paint or boiled oil, 1 coat of which may be applied before erection; or
(b) provided with such other protection against corrosion as the Building Authority may approve.
(2) The coatings of paint or boiled oil, or other protection against corrosion, shall, in the case of all surfaces inaccessible after erection (except surfaces held in direct contact by riveting or intermittent welding) be applied before erection.