Working initially with concept sketches, the team elaborated a design for cradle manufactured from welded steel C-section boxes, resembling a small cage, whose dimensions would be 1m x 1.5m x 1.2m: the minimum space required to take the jack and the removed block and allow room around to work.
They then performed multiple calculations and design iterations to ensure the structure would be robust enough to take the force from the hydraulic removal and the concrete should it slip. An extra steel plate was added to the cradle floor to handle the loads as the block dropped onto the cradle. Further design iterations were needed to elaborate a lockable gate and lever arm mechanism for locking and removing the cradle onto the supporting formwork.
The formwork tower would need to be modular so it could be easily brought onto the site. This added a benefit to the process: each time the cradle was lifted off to transport the removed block to ground, a 1 m high modular section of the tower could be quickly removed, so the cradle could be replaced one meter lower and removal works could continue with minimal delay in a carefully planned incremental sequence of works.
The team finally sent concept sketches to their appointed temporary works designer, who did the final calculations and recommended welds, causing a further round of design iterations. The final design was then fabricated by blu-3’s appointed metalworks provider.
The site team was then able to achieve further production efficiencies through streamlining the on-site sequence and are confident they now have a repeatable process that can be deployed readily on future similar jobs.