B 106
[Subsidiary]
Increase in maximum permissible steel stresses.
CAP. 123] Building (Construction) Regulations [1985 Ed.
(3) Before adopting the higher stresses permitted for designed mixes the registered structural engineer responsible for the design shall give due consideration to the exactness of the method of design, deflexions, site conditions which may affect adversely the control or proper curing of the concrete, and such other factors as might influence his selection of the appropriate strength of concrete for the work.
(4) The requirements of regulation 116(2) shall apply to special and designed mixes, subject to the maximum permissible stresses specified in Table XXXIX.
158. (1) Subject to regulation 118, the upper limit for the maximum permissible stresses specified in Table XXIX may be increased to those specified in Table XLI.
L.N. 294/76.
TABLE XLI
Maximum permissible stresses in reinforcement in reinforced concrete
Kind of stress Mild steel complying with BS 4449:1969 Steel with minimum yield point / MPa Not exceeding 40 mm diameter Exceeding 40 mm diameter 140 125 Tension other than tension in shear reinforcement 0.55 for 210 whichever is the lesser. 0.55, or 155 whichever is the lesser. Tension in shear reinforcement 125 110 |0.55, or 155 whichever is the lesser. Compression in longitudinal reinforcement in axially loaded columns and in main reinforcement in beams and slabs where the compressive resistance of the concrete is not taken into account Compression in longitudinal reinforcement in columns other than axially loaded columns and in main reinforcement in beams and slabs where the compressive resistance of the concrete is taken into account The calculated compressive stress in the surrounding concrete multiplied by the modular ratio but not exceeding, as appropriate. 125 110 0.55 or 155 whichever is the lesser.