B 110
CAP. 123] Building (Construction) Regulations
[1985 Ed.
[Subsidiary]
(b) based on the resistance to crushing of the concrete in compression,
My = 7Pcbd12
where ds is the depth of slab forming the flange and the factor 7 has the values given in Table XLII.
TABLE XVII
Values of 7 for computing resistance moment based on the resistance to crushing of the concrete in compression
Values of 7 for ds/d1 1 2 3 4 5 6 7 hb/b 2 or less 0.25 0.25 0.25 0.25 0.25 0.25 3 0.25 0.22 0.20 0.185 0.175 0.125 4 0.25 0.20 0.17 0.15 0.14 0.062 6 0.25 0.195 0.165 0.14 0.125 0.042 8 0.25 0.19 0.16 0.135 0.12 0.031 10 0.25 0.185 0.145 0.12 0.10 0Formulae for short columns subject to both direct load and bending in load factor method.
Note: hb is the width of the rib.
(2) Where it is necessary for the resistance moment to exceed
My = 7Pcbd12, compressive reinforcement should be provided so that:
My = 7Pcbd12 + AscPsc(d1 — d2) M.
and the area of tensile reinforcement should be such that the stress in this steel does not exceed the permissible stress.
(3) For intermediate values of hb/b, and d1/ds the value of 7 can be calculated from the following formula:
...
(Formula is missing due to OCR damage)
165. (1) For columns of rectangular section with symmetrical reinforcement, the section should be assumed to be controlled by compression when the load exceeds Pb given by the following equation:
Pb = Pccbd1 X
Asc (Pst + Psc)
where-Pcc
d1
Asc
is the permissible stress for the concrete in direct compression;
is the breadth of the column;
is the effective depth to the tensile reinforcement; is the area of the compressive reinforcement: which for the conditions of bending to which the above equation applies is equal to of the total area of reinforcement in the column;
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