Sainsburys - As close as it gets
Case History for Sainsburys (Wombourne)
During this contract we had to erect a bi framed portal that was designed very slender sharing a spine beam in the valley.
Stresses imposed during erection would be far larger than any to be encountered when the building was complete. The stress on the spine beam meant both sides needed to be balanced during erection. Whilst the stress on the rafters would require the portal to remain on the hook to do this Two cranes would be used at precisely the same time to release the load, hence balancing the stresses.
You will note the left hand crane positioned to the right hand side of its bay, the right hand crane to the left hand of its bay enabling each crane to lift into each others bay. Hence could assist from the opposing bay to lift in restraining steelwork. And vica verca by positioning the steel trailer centrally both cranes could pick from it.
The frame was erected a week early