1985 Ed.]
Building (Construction) Regulations
[CAP. 123
B 95
[Subsidiary]
effective column length to least lateral dimension shown in Table XXX. When, in a column having helical reinforcement, the permissible load is based on the core area, the least lateral dimension shall be taken as the diameter of the core.
(2) (a) Bending moments in internal columns supporting an approximately symmetrical arrangement of beams and loading shall not be required to be calculated except in the case of flat slab construction.
(b) Bending moments in external columns and in internal columns supporting an arrangement of beams and loading not approximately symmetrical shall be calculated and provided for. The expression given in Table XXXVI shall be used for estimating moments.
TABLE XXXVI
Moments in columns
Moments for frames of 1 bayMoments for frames of 2 or more bays External and similarly loaded column Moment at foot of upper columnM =K1
K1 + K2 + 0.5 KhM =
Ku
K1 + K1 + Kf Moment at head of lower columnM =
KL
K + K1 + 0.5 KM =
KL
K + K1 + K12 Internal column Moment at foot of upper columnM = ...M = ... Moment at head of lower columnM =
KL
K1 + K12 + K2 + Kh2
Note:
(1) MEV is the bending moment at the end of the beam framing into the column, assuming fixity at both ends of the beam;
MEN is the maximum difference between the moments at the ends of the 2 beams framing into opposite sides of the column, each calculated on the assumption that the ends of the beams are fixed and assuming one of the beams unloaded;
Kh is the stiffness of the beam;
Kh1 is the stiffness of the beam on 1 side of the column;
Kh2 is the stiffness of the beam on the other side of the column;
K1 is the stiffness of the lower column;
Ku is the stiffness of the upper column.
(2) The stiffness of a member shall be obtained by dividing the moment of inertia of a cross-section by the length of the member, provided that the member is of constant cross-section throughout its length.
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