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)

368 Prestressed concrete simple beams
StepS
Ve = Yeo of Step 2 (since Yeo < Ver)
= 448 kN
0.8Heu = 0.8~50 = 5.66 N/mm 2 > 5 N/mm 2
Hence the upper limit on VI bvd is 5 N/mm 2 •
Actual Vlbvd (see Step 1: Case 2)
Step6
- (400)(10 3 ) - 2
- (200)(790) - 2.53 N/mm OK
V = 400 kN (Step 1: Case 2)
Ve = 448 kN
Hence Vis not less than 0.5Ve. Move to Step 7.
Step7
By inspection,
V > 0.5Ve but < (Ve + 0.4bvd)
From eqn (9.6-5),
Asv (0.4)(200)
s; = (0.87)(250)
= 0.37 mm
From Table 6.4-2,
Provide size 10 links at 300 mm centres (Asvlsv = 0.52)
For further reading on shear in prestressed concrete, the reader is referred
to References 1-3 and 8-13.
9. 7 The ultimate limit state: torsion (BS 8110)
The torsional resistance of a prestressed concrete member is significantly
higher than that of the corresponding reinforced concrete member [1-3].
However, BS 8110 is cautious; it recommends that the same procedure as
explained here in Section 6.11 for ordinary reinforced concrete members
should be used for the torsion design of prestressed members.
The effect of prestressing on the torsional behaviour of concrete
members, both under service condition and ultimate-load condition, is
explained on pp. 57-65 of Reference 2, which also includes comments on
design procedure.
9.8 Short-term and long-term deflections
In Chapter 5 it was pointed out that, in assessing the deflections of
reinforced concrete beams, an efficient and general method was to work