Buro Happold on team behind Birmingham’s innovative ‘Cube’

17/11/2010 Written by: Chris White

Practice plays key role on landmark building with striking façade

International multi disciplinary engineering consultancy Buro Happold provided a range of services – including structural, civil, geotechnical and facade engineering – on the recently completed Cube development in the heart of Birmingham.

The high quality, mixed use building comprises a five storey basement and 17 above ground floors to provide 40,000m2 of retail and office space and residential and hotel accommodation – as well as a roof top restaurant that provides spectacular views across the city.

The mix of uses is designed to foster a vibrant 24/7 community and, by linking the canal and city centre, through to Attwood Green in the south west of the Birmingham, the Cube promises to play a key role in the regeneration of the city’s Eastside area.

Construction next to existing buildings and canals provided a major challenge for the practice’s team of structural and geotechnical engineers who developed a strategy to monitor ground and building movements during the works.

The design of the main structure, involving post tensioned slabs supported on a regular grid of columns, was optimised by the practice’s team to optimise the planned hotel, residential and office lay outs and take full advantage of the site’s layout. The team also designed the regular floor plate to step back at residential levels to create open terraces for apartments.

The 50m cube building was designed with striking bronze aluminium cladding and features two dramatically different types of façade which required the practice’s team of specialist façade engineers to develop bespoke engineering specifications.

The outer envelope is entirely clad by a unitised curtain wall and has the appearance of a gigantic jigsaw of clear glass and bronze-tinted metallic panels. The comparatively solid façade was chosen for both architectural and functional reasons and to keep the summer solar gain and winter energy consumption within required criteria.

Colour anodising was selected for its durability and resistance to aggressive weathering and because its appearance changes dramatically throughout the day to provide a stunning finish that varies from a matt to a shimmering effect depending on the light level.

The team designed the internal façade, which faces the inner courtyard, to replicate the pattern effect of the outer envelope but in glass. This was achieved using glazed spandrel panels with white fritting and by focusing light down through the central atrium to create an intimate atmosphere at the canal level retail units.

Along the canal-facing side of the building the team designed the cladding to open up to enable views, air and sunlight through to the residential terraces. The team faced the challenge of developing a sculptural element which was solid enough to provide the visual integrity of the fourth side of the Cube while maintaining an open nature for the residents.

This was achieved through the use of a filigram screen to fill a 30m high and 50m wide triangular void in a random manner similar to the other three facades.

The team designed the high horizontal and vertical loads to be transferred back to the main frame using a two way ‘net’ formed in large 400mm square steel box sections and entirely encased in anodised aluminium cladding units.

Basement works involved the construction of a 900mm diameter contiguous bored pile wall around the excavation to support up to 19m of soil and rock. To control ground movements and maintain stability the wall was propped with a combination of pre-stressed anchors, struts and beams.

The basement is designed to house retail and parking areas and to maximise parking and reduce the impact on retail space a fully automated parking system was incorporated to accommodate up to 330 vehicles.