Currently the tallest construction site in the UK, TwentyTwo Bishopsgate will become the second tallest in Western Europe, after The Shard. The building is being erected on the former site of a previous project. The main structural challenge faced was to reuse the existing foundations and basement, designed and built for a completely different scheme, and provide 30 per cent more built area than its predecessor.
Over the next 50 years, as space becomes more scarce, opportunities will be found in existing sites and buildings. Re-using and recycling their basements and foundations will be important to provide a more viable and sustainable solution. This presentation will include:
- Foundation strategy, re-using 100% of the previous building’s piles, minimising the need for new foundation elements being built.
- Additional piles and their interaction with the existing structure and the soil.
- New raft construction for a larger concrete core, and its interaction with the existing structure.
- Plastic analysis of the existing basement structure and the effect of the new construction methodology.
- Re-use and recycling of existing basement slabs and other concrete elements.
- Top-Down construction methodology of the concrete core, allowing 20 storeys of it being built before completing the foundation works.
- Other mega transfer structures required to divert the building loads towards the existing foundations.
Through mega transfer girders, inclined columns with high strength steel cable ties, partial demolition of the existing basement, and top-down construction of 20 levels of core, the solutions to the challenges faced at TwentyTwo Bishopsgate cut through complexity, delivering an efficient system for a sustainable and environmentally conscious building that re-uses 100% of the existing foundations.