Civil Engineering Reference
In-Depth Information
The pier segment plus at least one adjacent segment are generally placed by crane.
This provides a platform on which the fi rst set of shear legs may be placed. Once an
additional segment has been placed, the shear legs are moved forwards and the second
set may be lifted into position.
When it is not possible to lift in the pier segment by crane, the pier head falsework
may be designed to support the fi rst set of shear legs which places the pier segment
itself. The shear legs may be assembled on the falsework.
Generally, shear legs erect only one segment per day at each end of the double
cantilever with permanent prestress installed in each pair of segments. After each
pair of segments has been erected, the shear legs are moved forwards. However, they
may be designed to erect two segments from each position, when the deck should be
designed with permanent cables anchored every two segments, and a construction
rhythm of four segments per day adopted.
Figure 15.31
Byker Viaduct: erection using shear legs (Photo: J. Mowlem/North East Studios)
