The Dandara residential development is the second development on the Arena Central site and consists of twin towers, 21 and 25 storeys respectively, linked at each floor by bridges. Providing accommodation for 322 apartments and 7245 ft2 of commercial space.
The building has two levels of basement providing 500 space carparking. The building was built for a total cost of £40m.
BWB provided full Civil Structural and Geotechnical Services for this project from inception to completion, employed by the contractor developer partner Galliford Try.
The building is located on the Arena Central developments adjacent to the iconic Alpha Tower on the site of the former Britannia Carpark. Bounded by Holliday Street and Suffolk Street Queensway, the building is a prominent landmark dominating the skyline when viewed from Suffolk Street Queensway.
Due to the close proximity of the building to the network Rail tunnel, detailed negotiations were carried out by BWB culminating in a need for a full 3D finite element model being produced to prove that the tunnel lining and track bed were not affected by our development.
The rail tunnel takes two form. One is a traditional Victorian brick lined whilst the other was once an open cutting with brick retaining walls and more recently added precast concrete cover during the Alpha Tower and Crowne Plaza development.
As our building sits to one side of the tunnels uneven lateral stresses were expected to be created that could destabilise the tunnel linings particularly the Victorian brick bored tunnel.
During construction the tunnel linings and track bed were monitored to ensure that no excessive movements were experienced particularly in the Victorian tunnel where headroom is at a minimum.
The key structural challenge is the 9.8m cantilevered gable of the 25 storey tower nearest Suffolk Street Queensway.
This cantilever supports 21 storeys of living accommodation and roof. The cantilever was achieved by concrete slab heavily top reinforced requiring careful placing of concrete to ensure there are no voids.
The concrete mix was designed with high cement replacement and retarding admixtures to ensure that the risk of thermal shock leading to cracking was minimised whilst the shuttering remained in place for longer than normal to reduce the thermal gradient.