Project Brief
We provided civil and structural engineering services, including:
- Radiation-protected concrete ‘bunker’ rooms for a linear accelerator machine
- An extension/conversion to create new treatment areas
- Chiller plant compound
Initially appointed to review design proposals from others, our appointment was extended to include designing the foundations, suspended ground floor slab, steel frame, concrete construction, underground surface and foul water drainage, external works build-ups, and retaining walls. We also provided support for the contractor’s appointment.
Solution
Through an early collaborative value-engineering exercise, we proposed two innovative solutions to improve the original design proposals for the extension.
Prior to our involvement, the initial solution suggested cantilever reinforced concrete transfer beams to allow the original car park columns to be removed. Connecting very large cantilever beams to the new concrete ‘bunker’ would have been an expensive, time-consuming solution requiring temporary support for the car park slab. We designed-out these intrusive works, proposing a simpler alternative using prefabricated steel beams and columns. Our design saved costs and reduced the programme by around two weeks. Reducing the concrete also helped minimise the carbon outputs.
Secondly, we agreed with the contractor an innovative method to construct the 2 metre thick reinforced concrete bunker walls by harnessing the scientific behaviour of curing concrete. Instead of a traditional Portland cement mix, we recommended a grade containing more Ground Granulated Blast Furnace Slag, to reduce the peak temperature of the setting concrete and lower the risk of cracking. Collaborating with a concrete expert, we used their thermal modelling tools to provide the appropriate reinforcement. Planning the pour sequencing with the contractor, we significantly reduced the steel reinforcement quantities.
We attended weekly meetings to support progress of the tight programme, working closely with the architect and project manager to keep detailing simple and cost effective.
