Nemetschek Engineering User Contest 2009 • Category 2: CAE Housing & Buildings 71 2 downstand beams with the breakout zone comprising a semi-precast concrete system. Due to the requirements of the utility providers the slab to the transformer room is placed at a depth of 1.1 m below the main slab requiring reinforced concrete beams to achieve acceptable deflection requirements. Superstructure The structural frame comprises an in situ reinforced concrete frame utilising a column grid of 7.6 m x 9.0 m. The structure comprises a 325 mm reinforced concrete flat slab spanning between columns varying in size depending on level and location but are generally 800 x 300 mm in bedroom floors and 600 mm diameter in public areas. Transfer structures are required primarily at first floor level to create an acceptable column layout on the lower floors, the transfer being achieved using in-situ reinforced concrete downstand beams spanning between reinforced concrete columns, all transfer beams being designed to resist blast loadings. The 8th floor above which the apartment structure commences utilises a 450 mm deep flat slab to transfer the loadings from the apartment levels above to the main frame. The floor slabs are designed to accommodate the following uniform imposed load set out below. Guestroom floors • Bedroom live load: 2.0 kN/m2 • Partitions: 1.5 kN/m2 • Corridor and staircase live load: 4.0 kN/m2 • Ceiling and services: 0.5 kN/m2 Public /Business/Administration area • Live load: 5.0 kN/m2 • Partitions: 1.0 kN/m2 • Ceiling and services: 0.5 kN/m2 Other areas in the building will be designed to accommodate the following live loads • Public toilets: 2.0 kN/m² • Kitchen and ancillary areas: 3.0 kN/m2 • Roof (maintenance access only): 1.0 kN/m² • Plant rooms: 7.5 kN/m² • Loading bay and car parking areas: 15.0 kN/m² The building has an entirely glass façade, the façade and unitised system being contractor designed with the structural frame having to be designed for deflection limits of the lesser of L/500 or 20 mm under imposed loads and creep deflections and L/250 under dead and imposed loads, the deflection limitations being of paramount importance on slab edges due to the glazed façade of the building attaining lateral support at each fl oor. Resistance to lateral loads is achieved by the diaphragm action of the reinforced concrete floors transferring the lateral loads to a series of concrete shear walls primarily around the lift cores, the shear walls generally 250-300 mm thick reinforced concrete elements constructed using conventional formwork technology. The structure is also designed for disproportionate collapse with key elements designed as protected members to provide additional robustness and damage resistance. The building is currently under construction and is due to be completed in Spring 2010. Swiss Centre, Leicester Square, London
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