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 =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.
Page 95
Page 96
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 reinforce- ment, 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 XXXVF
Moments in columns
Moments for
Moments for frames of 1 bay
frames of 2 or more bays
External and
Moment at foot of upper column
M
K1
K¿+ K2+0.5 Kh
Ku
M
K;+ K1 + Kƒ
similarly
loaded
K
column
Moment at head of
KL
M
M
lower column
K+K1+0.5K
K+K1+K12
#
Internal
Moment at foot of
M
*'*
K
column
upper columa
K
Moment af head of lower column
M
EN
K; + K12+K2+ Kn2
Note:
(1) M
M
EV
is the bending moment at the end of the beam framing into the column, assuming fixity at both ends of the beam:
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;
Khi
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:
Ki
is the stiffness of the lower column:
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.
Page 95Page 96
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