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)

328 Reinforced concrete slabs and yield-line analysis
Table 8.8-1 Fire resistance requirements for slabs (BS 8110: Part2: Clause 4.3.1)
Fire
rating
(hours)
1
2
3
4
Minimum thickness
(mm)
Simply
supported Continuous
95 95
125 125
150 150
170 170
Concrete cover to
MAIN reinforcement (mm)
Simply
supported Continuous
20 20
35 25
45" 35
55" 45.
" See BS 8110: Part 2: Clause 4 for protection against spalling.
not differ by more than 15% of the longest span [ 1]. In these rules, I refers
to the effective span length and ¢ the bar size.
(a) Simply supported slabs: All the tension bars should extend to within
0.11 of the centres of the supports. At least 40% of these bars should
further extend for at least 12¢ (or its equivalent in hooks or bends)
beyond the centres of the supports.
(b) Cantilever slabs: All the tension bars at the support should extend a
distance of //2 or 45¢, whichever is greater. At least 50% of these
bars should extend to the end of the cantilever.
(c) Continuous slabs:
(1) All the tension bars at the support should extend 0.15/ or 45¢
from the face of the support, whichever is greater. At least 50%
of these bars should extend 0.3/ from the face of the support.
(2) All the tension bars at midspan should extend to within 0.2/ of
the centres of supports. At least 40% of these bars should
extend to the centres of supports.
(3) At a simply supported end, the detailing should be as given in
(a) for a simply supported slab.
8.9 Design and detailing-illustrative example
See Example 11.5-1.
8.10 Computer programs
(in collaboration with Dr H. H. A. Wong, University of Newcastle upon
Tyne)
The FORTRAN programs for this chapter are listed in Section 12.8. See
also Section 12.1 for 'Notes on the computer programs'.