B 98
[Subsidiary]
Columns and column heads in flat slab construction. L.N. 294/76.
CAP. 123] Building (Construction) Regulations
[1985 Ed.
(b) at a distance from the drop of the thickness of the slab,
as shown in Diagrams 6, 7 and 8.
(2) The shearing stresses at the critical sections shall not exceed the permissible values specified in regulation 116.
150. (1) Columns supporting flat slabs shall not be less than 300 mm in diameter.
(2) When column heads are provided, the interior column heads and such parts of the exterior column heads as will lie within the building shall satisfy the following requirement-
(a) the angle of slope of the column head shall not exceed 45° from the vertical;
(b) the diameter (D) of the column head shall be measured at a distance 40 mm below the slab or drop; and
(c) the diameter (D) shall not exceed
as shown in Diagrams 7 and 8.
(3) For the purposes of paragraph (2), where column and column head are not circular in cross-section the term diameter (D) shall be deemed to mean the diameter of the largest circle which can be drawn within the actual section at a distance of 40 mm below the slab or drop.
(4) No part of any column head which lies outside the envelope described in paragraph (2) shall be considered for structural purposes.
DIAGRAM 6
Critical section for shearing stress in flat slabs without drop and column without column head
CRITICAL SECTION
FOR SHEAR