B 92
CAP. 123]
Building (Construction) Regulations
[1985 Ed.
[Subsidiary]
Floors and roofs of ribbed and hollow block construction.
(c) The bar shall extend at least 12 bar diameters beyond the point at which it is no longer required to resist stress.
(9) (a) Laps in bars in any member shall be staggered wherever practicable.
(b) The length of lap in bars in tension shall be not less than—
the bar diameter × the tensile stress in the bar
4 times the permissible average bond stress
30 bar diameters,
whichever is the greater.
(c) The length of lap in bars in compression shall be not less than—
the bar diameter × the compressive stress in the bar
5 times the permissible average bond stress
24 bar diameters,
whichever is the greater.
(10) (a) In the case of deformed bars, the bond stresses shall not exceed those permitted in regulation 116 by more than 25 per cent.
(b) For the purpose of this paragraph, a bar is deformed if its bond strength exceeds that of a plain round bar by 25 per cent or more.
(11) All bent up bars acting as shear reinforcements shall be fully anchored in both flanges of the beam, the anchorage length being measured from the end of the sloping portion of the bar.
142. (1) In this regulation, a floor or roof of ribbed and hollow block construction means a floor or roof which consists of a series of reinforced concrete ribs cast-in-situ—
(a) between blocks which remain part of the completed floor or roof; or
(b) on forms which may be removed after the concrete has set.
(2) Blocks and forms shall be of suitable material which will retain its shape and dimensions and is strong enough to support the concrete when placed.
(3) The tops of the ribs shall be connected by a topping of concrete, of the same quality as the concrete used for the ribs and cast-in-situ, over the blocks or forms.
(4) The blocks shall be neglected in determining the bending and shearing resistance of hollow block construction.