2 Aldermanbury Square
Location: City of London, London
Client: Keltbray / Lendlease / Great Portland Estates
Location: City of London, London
Client: Keltbray / Lendlease / Great Portland Estates
CapabilitiesCapabilities
- Buildings
- Substructure
- Hydraulic Jacking
- Demolition
- Structural Engineering
- Geotechnics
- Construction Method Engineering
- Temporary Works
- 3D Modelling
- Social Value and Sustainability
- Wentworth Labs
- Buildings
- Substructure
- Hydraulic Jacking
- Demolition
- Structural Engineering
- Geotechnics
- Construction Method Engineering
- Temporary Works
- 3D Modelling
- Social Value and Sustainability
- Wentworth Labs
SummarySummary
2AS is an office led redevelopment carried out by Keltbray and Lendlease for the developer GPE. It aims to deliver a net zero carbon building and is a showcase for the reclamation and re-use of structural steel.
The 2AS project centres around the demolition and reconstruction of an aging commercial tower occupying a confined urban site within central London. Following the demolition works, Keltbray constructed a new basement box and 12-storey core for the new 2AS with Wentworth developing the methodology and designing the temporary works.
The 2AS project centres around the demolition and reconstruction of an aging commercial tower occupying a confined urban site within central London. Following the demolition works, Keltbray constructed a new basement box and 12-storey core for the new 2AS with Wentworth developing the methodology and designing the temporary works.
2AS is an office led redevelopment carried out by Keltbray and Lendlease for the developer GPE. It aims to deliver a net zero carbon building and is a showcase for the reclamation and re-use of structural steel.
The 2AS project centres around the demolition and reconstruction of an aging commercial tower occupying a confined urban site within central London. Following the demolition works, Keltbray constructed a new basement box and 12-storey core for the new 2AS with Wentworth developing the methodology and designing the temporary works.
The 2AS project centres around the demolition and reconstruction of an aging commercial tower occupying a confined urban site within central London. Following the demolition works, Keltbray constructed a new basement box and 12-storey core for the new 2AS with Wentworth developing the methodology and designing the temporary works.
Delivering valueDelivering value
Wentworth resident engineering team worked with the construction team to evolve the demolition and substructure methodologies and helping to plan, de-risk and design the required temporary works.
Wentworth worked alongside the permanent works engineer to minimise carbon emissions, maximise re-use of the existing materials, and salvage 1500 tonnes of the existing steel frame for reuse.
This project showcased engineering excellence through the meticulous dismantling and reuse of existing steel structures. All steel members were assessed, sized for reuse, and stored safely awaiting transport for processing. This logistical feat was expertly and safely executed.
We are immensely proud of the engineering expertise we brought to the project, and the synergistic collaboration with Wentworth, Arup and Keltbray, to enable the client’s challenging vision of delivering a building that goes beyond embodied carbon norms for a new build development by integrating principles of circular economy.
Wentworth worked alongside the permanent works engineer to minimise carbon emissions, maximise re-use of the existing materials, and salvage 1500 tonnes of the existing steel frame for reuse.
This project showcased engineering excellence through the meticulous dismantling and reuse of existing steel structures. All steel members were assessed, sized for reuse, and stored safely awaiting transport for processing. This logistical feat was expertly and safely executed.
We are immensely proud of the engineering expertise we brought to the project, and the synergistic collaboration with Wentworth, Arup and Keltbray, to enable the client’s challenging vision of delivering a building that goes beyond embodied carbon norms for a new build development by integrating principles of circular economy.
Wentworth resident engineering team worked with the construction team to evolve the demolition and substructure methodologies and helping to plan, de-risk and design the required temporary works.
Wentworth worked alongside the permanent works engineer to minimise carbon emissions, maximise re-use of the existing materials, and salvage 1500 tonnes of the existing steel frame for reuse.
This project showcased engineering excellence through the meticulous dismantling and reuse of existing steel structures. All steel members were assessed, sized for reuse, and stored safely awaiting transport for processing. This logistical feat was expertly and safely executed.
We are immensely proud of the engineering expertise we brought to the project, and the synergistic collaboration with Wentworth, Arup and Keltbray, to enable the client’s challenging vision of delivering a building that goes beyond embodied carbon norms for a new build development by integrating principles of circular economy.
Wentworth worked alongside the permanent works engineer to minimise carbon emissions, maximise re-use of the existing materials, and salvage 1500 tonnes of the existing steel frame for reuse.
This project showcased engineering excellence through the meticulous dismantling and reuse of existing steel structures. All steel members were assessed, sized for reuse, and stored safely awaiting transport for processing. This logistical feat was expertly and safely executed.
We are immensely proud of the engineering expertise we brought to the project, and the synergistic collaboration with Wentworth, Arup and Keltbray, to enable the client’s challenging vision of delivering a building that goes beyond embodied carbon norms for a new build development by integrating principles of circular economy.
Key scopeKey scope
- Demolition engineering: Demolition sequencing and assessment of existing structures to allow safe de-construction sequence without overloading neighbouring assets.
- Retaining wall assessment: Verification and assessment of the existing retaining walls to validate their stability and suitability for a deeper excavation.
- Basement propping: Development of a sequence of prop installation and basement raft demolition that maintained retaining wall stability, cross site load balance and enabled access for large demolition plant to break out the existing basement raft.
- Demolition engineering: Demolition sequencing and assessment of existing structures to allow safe de-construction sequence without overloading neighbouring assets.
- Retaining wall assessment: Verification and assessment of the existing retaining walls to validate their stability and suitability for a deeper excavation.
- Basement propping: Development of a sequence of prop installation and basement raft demolition that maintained retaining wall stability, cross site load balance and enabled access for large demolition plant to break out the existing basement raft.
Key Challenges and SolutionsKey Challenges and Solutions
- Construction Method Engineering: Wentworth worked with Keltbray to plan and execute a method to allow for the steelwork to be removed at maximum length without damage. This involved detailed survey and assessment of the existing steel frame to accommodate the plant needed on the existing floor plates and to prescribe a detailed sequence of down taking.
- Geotechnical Design: Wentworth undertook detailed geotechnical design to assess the existing piled basement walls so that they could be reused to retain the 14m deep excavation for the new extended basement box. This was a significant challenge given the sensitivity to ground movement of existing heritage structures and nearby utilities and the resulting tight deflection criteria.
- Structural Design: The basement wall retention required multi-phased, jacked, steel propping - working in a carefully determined sequence - as the existing basement was demolished, the ground excavated, and the new RC box constructed around the propping. The 180T of steel CHS propping was designed based on an existing stock of reclaimed steel. By designing to accommodate re-use we saved over 300,000 kgCO2e.
- Temporary works design: beyond the key elements described above we designed some 40 temporary works schemes including back-propping, tower crane bases, core stability, cantilevering scaffold supports, and temporary logistics gantries.
- Construction Method Engineering: Wentworth worked with Keltbray to plan and execute a method to allow for the steelwork to be removed at maximum length without damage. This involved detailed survey and assessment of the existing steel frame to accommodate the plant needed on the existing floor plates and to prescribe a detailed sequence of down taking.
- Geotechnical Design: Wentworth undertook detailed geotechnical design to assess the existing piled basement walls so that they could be reused to retain the 14m deep excavation for the new extended basement box. This was a significant challenge given the sensitivity to ground movement of existing heritage structures and nearby utilities and the resulting tight deflection criteria.
- Structural Design: The basement wall retention required multi-phased, jacked, steel propping - working in a carefully determined sequence - as the existing basement was demolished, the ground excavated, and the new RC box constructed around the propping. The 180T of steel CHS propping was designed based on an existing stock of reclaimed steel. By designing to accommodate re-use we saved over 300,000 kgCO2e.
- Temporary works design: beyond the key elements described above we designed some 40 temporary works schemes including back-propping, tower crane bases, core stability, cantilevering scaffold supports, and temporary logistics gantries.