The 150 Bishopsgate (One Bishopsgate Plaza) development is a 43-storey mixed use tower with 4 levels of basement comprising of public space, retail, high end hotel and residential apartments and is situated adjacent to the Heron tower.
The tower is 135m in height and is Europe’s first Pan Pacific hotel, which includes a subterranean double height ballroom (the only one in the square mile!) and an exclusive health club including a pool, gym, studio space and spa on level 4. The “Sky Residences” are located in the top 21 levels of the tower with the lower levels for hotel guests and public spaces.
Levels 1 through to 42 were designed as post-tensioned by Praeter Engineering, typically at 200mm thick with a localised 225mm thick area to the cantilevered corners. Praeter had various issues to contend with for such a thin slab such as heavy marble finished bathroom pods, 8-8.5m single spans, walking columns and 3 “corners” of the building required column free cantilevered areas to ensure un-restricted views.
Praeter and WSP developed the design of the floor plates to include a supporting hanger system to the 3 corners to provide the unrestricted views. The final design ensured that the slab could satisfy the ultimate design in the unlikely event of a hanger bar failure i.e. the cantilevered slab areas would not collapse.
In order to speed up the construction installation process all of the tendon anchorages were fixed to a re-useable metal edge shutter and all reinforcement was pre-fabricated prior to arriving on site. These innovate ways of working are things that we have adopted with our client Expanded Structures on previous projects we have completed. All columns were precast double height except the exposed triple height circular columns on display at the entrance to the building. The core was constructed using a jump form system to ensure that construction of the core did not affect the superstructure floor plate programme.
Praeter also carried out the bolt tensioning of the tower crane grillage that supported the tower crane throughout the construction process.