4.2 - VSL

anchorage into sections of 46.3 and 37 m
length. This enabled a reduction in the free
strand length to be achieved with a
corresponding increase in the ultimate
strength. The ends of all the monostrands in
the longitudinal direction are fitted with VSL
stressing anchorages. The strands in the
transverse direction also utilize intermediate
anchorages in the horizontal areas of the
slabs. These anchorages are, however,
located at the construction joints and
therefore served as stressing anchorages
(Fig. 109). The remaining transverse strands
have a deadend anchorage at one end and
stressing anchorages at the other.
In the seven lower slabs, the quantity of posttensioning
steel is 3.7 kg/m 2
, and in the roof
slab it is 6.0 kg/m 2
. The quantities of ordinary
reinforcement required were 6.4 kg/m 2
and
12 kg/m 2
respectively (including 1 kg/m 2
fixing steel for the tendons in each case).
This low reinforcement content is explained
by the fact that no bottom reinforcement was
necessary in the internal spans.
9.12. Summary
Some important data for the slabs described
in Chapters 9.2. to 9.11. are summarized in
Table VIl. When a comparison is being made
between the values, it must be remembered
however that different standards were used
for different projects and the design methods
have progressively developed in the course
of time.
Table VI I - Main data of the structures described in Chapters 9.2. to 9.1 1.
F=Flab slab B=Slab with main beams w=Waffle slab
Figure 108: Extract from the construction programme
Figure 109: Construction joint with stressed intermediate anchorages
37