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)

344 Prestressed concrete simple beams
Consider midspan section
Mimax = 250 kNm Mimin = 0 Md = 34.5 kNm
(all from Example 9.2-2).
Therefore, from eqn (9.2-18),
Similarly,
> 250 X 10 6 + 34.5 X 10 6 19.0 X 10 6
es - 837 X 1<P - 120,000
19.0 X 10 6 X (-2.6)
+ 837 X 103
~ 124 mm
e 5 ~ 93 mm (from eqn 9.2-19)
e 5 ::::::; 257 mm (from eqn 9.2-20)
e 5 ::::::; 288 mm (from eqn 9.2-21)
Therefore, eqns (9.2-18) and (9.2-20) govern (at this section and at all
other sections).
Consider section at 3 m from support
Mimax = 150 kNm, Mimin = 0, Md = 29.1 kNm (and the reader should
verify these values).
From eqn (9.2-18): e 5
~ -2 mm
From eqn (9.2-20): e 5 ::::::; 251 mm
Consider section from 1 mfrom support
Mimax =50 kNm, Mimin = 0, Md = 12.4 kNm (again the reader should
verify these).
From eqn (9.2-18): e 5 ~ -142 mm
From eqn (9.2-20): e 5 ::::::; 231 mm
Consider support section
Mimax = Mimin = Md = 0
From eqn (9.2-18): es ~ -216 mm
From eqn (9.2-20): e 5 ::::::; 216 mm
The permissible tendon zone is as plotted in Fig. 9.2-4.
pper limit of tendon zone
Fig. 9.2-4 Permissible tendon zone