Civil Engineering Reference
In-Depth Information
it is not necessary to check the transverse bending as a Vierendaal girder, and it is also
unnecessary to provide corner bars trimming the voids. For decks with abnormally high
transverse bending, due for instance to an irregular pier arrangement, it is prudent to
check the Vierendaal action and to provide corner bars.
11.5.6 Casting the concrete
Concreting voided decks requires more care than for solid slabs, as there is the risk of
incomplete fi lling and compaction beneath the voids. Consequently it is a slower and
more labour-intensive operation. The normal method for decks with circular voids is
to work across the deck, fi lling one rib and observing the concrete fl owing out from
beneath the adjacent void.
11.5.7 The development of voided slabs
The development of voided slabs is similar to that of solid slabs. In decks where the
maximum stress on the bottom fi bre is less than the permissible limit, it is cost effective
to create side cantilevers and to remove material from the centre of wide slabs, creating
effectively a voided ribbed slab, Figure 11.15. Alternatively, the slab may be provided
with haunches at intermediate supports, allowing the slab to span further.
Figure 11.15
Voided ribbed slab
