F. K. Kong MA, MSc, PhD, CEng, FICE, FIStructE, R. H. Evans CBE, DSc, D ès Sc, DTech, PhD, CEng, FICE, FIMechE, FIStructE (auth.)-Reinforced and Prestressed Concrete-Springer US (1987)

410 Practical design and detailing
tion procedure, on the assumption that the column and beam ends
remote from the junction under consideration are fixed and that the
beams possess half their actual stiffness, as shown in Fig. 11.4-1(h).
The loading arrangement should be such as to cause the maximum
moment in the column; thus, referring to Fig. 11.4-1(h), the longer
of the beams AB and BC would carry the load (1.4Gk + 1.6Qk) and
the shorter of the two beams would carry the load l.OGk.
An even greater simplification may be used in the continuous beam
analysis if:
(1) the characteristic imposed load Qk does not exceed the characteristic
dead load Gk;
(2) the load is fairly uniformly distributed over three or more spans;
(3) the variation in the spans does not exceed 15% of the largest.
If these conditions are met, BS 8110: Clause 3.4.3 states that the ultimate
bending moments and shear forces are to be obtained from Table 11.4-1.
It is convenient here to explain the loading arrangement for slabs. BS
8110: Clause 3.5.2.3 states that slabs may be designed for a single loading
case of maximum design ultimate load (1.4Gk + 1.6Qk) on all spans
provided that the following conditions are met:
(1) In a one-way slab, the area of each bay exceeds 30m 2 . In this context,
a bay means a strip across the full width of a structure bounded
on the two other sides by lines of supports. Thus, referring to the
typical floor plan in Fig. 11.5-1, each bay is 5.5 by 16m= 88m 2 •
(2) The ratio Qk/Gk :5 1.25, where Qk is the characteristic imposed load
and Gk the characteristic dead load.
(3) Qk does not exceed 5 kN/m 2 , excluding partitions.
(4) The variation in the spans does not exceed 15% of the longest. (BS
8110: Clause 3.5.2.4 uses the phrase 'approximately equal span'; the
specific reference to 15% has been taken from the I.Struct.E. Manual
[20]).
If these conditions are met, BS 8110: Clause 3.5.2.4 states that the
moments and shear forces in continuous one-way slabs may be obtained
from Table 11.4-2.
Table 11.4-1 Beams-Ultimate bending moments and shear forces
(BS 8110: Clause 3.4.3)
At Near At first At middle At
outer middle of interior of interior interior
support end span support span supports
Momenta 0 0.09Fl" -O.llFI 0.07F/ -0.08Fl
Shear 0.45F 0.60F 0.55F
• No further mom~;nt redistribution is allowed if the moment values of this table are used.
b F is the design load (1.4Gk + 1.6Qk) and I is the effective span of the beam.