Client: Aviva Life & Pensions UK
The redevelopment of Hanover Square, London comprised of 48,500 m2 of office space and 15,000 m2 of retail space. The redevelopment connects two properties that were separated by an internal courtyard.
Located in the City of Westminster, 11-12 Hanover Square combines commercial office space as well as retail façade along one of London’s busiest shopping areas. Hanover Square was constructed on a plot previously occupied by four separate properties separated by an internal courtyard.
The new building is 15 m wide x 50 m long and eight storeys high, entirely occupying the space between Hanover Square and Oxford Street.
The basement, ground and first floor are split in half with the areas closest to Oxford street being dedicated to 1,400 m2 of retail space. The Hanover Square facing areas of the building were dedicated to a plant room, entrance lobby and offices. The second to the seventh floor is dedicated to commercial office space.
The new building was constructed using a structural steel frame and composite concrete floors. BHC began erecting steelwork predominately on the ground floor, supported by the retaining wall and on concrete piers that extend upwards from the basement slab. Due to excessive loads coming down on the steel frame, four of the main steel columns are found on the basement floor and fixed in concrete up to the ground floor slab for stability. However, concreting the columns had to be left until the complete frame was erected, meaning that basement works were staggered.
BHC erected the steelwork in a regular grid pattern with the main steel column positioned along the site’s perimeters. In turn, this has given support to 15 m long cellular beams which have given the building its column-free spaces.
The majority of steelwork was erected using the onsite tower crane with the exception of a couple of transfer girders which were required due to the change in the grid pattern to accommodate the roof-top garden. The transfer girders weighed approximately 20 tonnes and were 15 m long, requiring a tower crane and had to be installed in a specially arranged weekend lifting operation.
The entire steelworks for this project, as well as the transfer girders, were lifted into place over three sets of temporary props that were installed across the site in order to support the neighbouring buildings. Due to height, BHC had to lift the beams over the props and then into the site’s footprint using a 500-tonne capacity crane.