1985 Ed.]
Building Construction) Regulations
[CAP. 123
B 83
[Subsidiary]
TABLE XXXIII
Approximate values of bending moments in uniformly loaded beams and slabs continuous over 3 or more approximately equal spans
3
5
I
Near middle
At support. At middle of:
At other
of end span
next to end
interior
interior
support
spans
supports
Wil
Wal
и
Moment due to dead load
12
10
24
12
Moment due to superim-
posed load
H
W
10
9
12
Note:
W is the total dead load per span.
W is the total superimposed load per span.
Spans may be considered as approximately equal when the shortest span is not less than 85 per cent of the longest span.
(2) Notwithstanding the provisions of paragraph (1), where beams are framed into external columns they shall be designed to resist bending moments in combination with the columns in conformity with regulation 143.
137. (1) The design of solid slabs spanning in 2 directions at right angles shall be based on either of the methods given in paragraphs (2) and (3).
(2) In order to estimate the bending moments in a slab spanning in 2 directions at right angles, the slab shall be assumed to act as a perfectly elastic thin plate, Poisson's ratio being assumed equal to zero.
(3) Where, in the case of a simply supported slab, adequate provision is not made to resist torsion at the corners of the slab and to prevent the corners from lifting, the bending moments at mid-span shall be assumed to have the values given by the following equations:
Ms = xs Wly2; My = xy Wly2/lx
where Mx and My are the bending moments at mid-span
on strips of unit width and spans lx and ly
respectively;
Slabs spanning in 2 directions at right angles with uniformly
distributed loads.
W'
is the total load per unit area;
ly
is the length of the longer side;
lx
is the length of the shorter side; and
xs and xy are coefficients shown in Table XXXIV.
1985 Ed.]
Building Construction) Regulations
[CAP. 123
B 83
[Subsidiary]
TABLE XXXIII
Approximate values of bending moments in uniformix loaded beams and slabs continuous over 3 or more approximately equal spans
3
5
I
Near middle
At support. At middle of:
At other
of end span
next to end
interior
interior
support
spans
supports
Wil
Wal
и
Moment due to dead load
12
10
24
12
Moment due to superim-
posed load
H
W
10
9
12
Note:
W is the total dead load per span.
W is the total superimposed load per span.
Spans may be considered as approximately equal when the shortest span is not less than 85 per cent of the longest span.
(2) Notwithstanding the provisions of paragraph (1). where beams are framed into external columns they shall be designed to resist bending moments in combination with the columns in con- formity with regulation 143.
137. (1) The design of solid slabs spanning in 2 directions at right angles shall be based on either of the methods given in paragraphs (2) and (3).
(2) In order to estimate the bending moments in a slab spanning in 2 directions at right angles, the slab shall be assumed to act as a perfectly elastic thin plate, Poisson's ratio being assumed equal to zero.
(3) Where, in the case of a simply supported slab. adequate provision is not made to resist torsion at the corners of the slab and to prevent the corners from lifting, the bending moments at mid- span shall be assumed to have the values given by the following equations:
M
M
X
2,117,2 Zy W/ 2
where M, and M, are the bending moments at mid-span
on strips of unit width and spans, and
respectively:
Slabs spanning in 2 directions at right angles with uniformly
distributed loads.
H'
is the total load per unit area:
W
is the length of the longer side;
is the length of the shorter side; and
and x, are coefficients shown in Table XXXIV.
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