Urbanest’s latest London scheme will have some of the most sought after views in the capital for its students and residents. Located next to County Hall and Waterloo Station, 199 Westminster Bridge Road overlooks the River Thames affording views of the Houses of Parliament and Big Ben. Designed by architects AHMM, the hybrid scheme will deliver 1,092 rooms in a variety of formats. Student accommodation is spread over 16 levels from floor 3 to the uppermost level 18. Below level 3, the lower part of the scheme includes four floors of college (ground, mezzanine, first and second floors), flexible and affordable workspace for small local start-up businesses, as well as a double height basement containing plant rooms, music rooms, a gym and a 16m x 5m swimming pool.

Level 3 of the scheme is essentially a transfer deck and the most crucial element of the project design as this is the main interface between the reinforced concrete residential zone and the steel framed college below. From basement level up to the third floor structural steelwork with metal decking has been used as the framing material and Bourne Steel fabricated, supplied and erected 1,570 tonnes of steel for this part of the scheme.

Steel was chosen for the college as the design includes a number of long span areas, such as a large central atrium. Bourne Steel’s erection sequence has been split into two programs. Initially the company erected the bulk of the project’s steelwork from basement slab up to third floor transfer level during a 12-week period in early 2014. Currently Bourne is working on a return visit to site erecting a further 80t of hot rolled steel to form the project’s sloping roof. The basement contains the initial elements of steelwork to be erected. This area contains a plant mezzanine formed with 3.5m high steel columns supporting metal decking, while longer 7m columns in the basement support the reinforced concrete ground floor slab.

From ground floor upwards the scheme’s steelwork zone incorporates a central atrium around which the college’s mezzanine, first and second floor facilities are arranged. Most of the steel beams are designed as downstand beams acting compositely with the slab above. Shear studs welded to the top flange of the beams provide the required composite action. However, there are a few areas of the building where composite construction was not suitable. Around the building’s perimeter and the internal atrium, primary beams are required to cantilever out from the columns. These beams are designed as non-composite as the top flanges will be in tension under hogging action. To ensure the internal spans still behave as composite sections all the moment from the edge cantilevers (both internal and external) are taken by the columns with pinned connections between the column and internal primary beams.