81 Newgate Street
The old BT Headquarters has been reimagined from its 1980s’s guise, to become the new HSBC Headquarters, moving from Canary Wharf back to the City’s Square Mile. The building will be extended from an original area of 47,900 to 75,300 square metres, a substantial increase. 81NGS is located in prime position close to St Pauls Cathedral.
The challenge is to keep the existing concrete frame, enhance the structure with new core layouts and adding on new floor plates and levels to maximise the buildings potential. This cut and carve project has a lot of difficult new elements that need to be detailed to connect, enhance and support the existing building. The aim is also to reduce the carbon created by keeping the original frame, with the additional benefit of reducing the construction programme’s length. Three cores need to be removed and replaced with modifications to the fourth core, new slab areas are required to increase the floor plate areas, and more height was required for increase space and provide more impressive views of the surrounding London vistas.
Our first reinforcement solution was to provide reinforcement layouts for the new cores, with a reasonably unique detail of connections into the existing slab floors at each level. We then needed to provide patches of new concrete reinforced deck slabs where concrete columns were replaced with fewer steel columns to open up floor areas. We then required to detail new insitu core and lobby slabs at the upper levels, along with 13 levels of concrete topped metal deck slabs. The decks, were more complex than normal, as dealt with different heights of existing and new steel beams. The metal decks were substantial in size making up the majority of the floor plate increase. The result will be a modern, Carbon sensitive building in the heart of London.