Temporary works design and brace removal at Heathrow Airport T2B Terminal.
Temporary works design and brace removal at Heathrow Airport T2B Terminal
Client: Heathrow Airport Limited
Principal Contractor: Balfour Beatty
Designer: Webb Yates Engineers
Works Commenced: July 2018
Works Completed: August 2018
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Terminal T2B is a new satellite terminal of the main Terminal 2 building, located to the east of the central Heathrow Airport site. For the final planned construction phase, Balfour Beatty requested Freyssinet’s assistance to design a system for the unloading and removal of a temporary bracing beam installed at VCC234 of T2B.
The 324mm diameter bracing was approximately 15m long and provided stability to the terminal. Once VCC 234 was complete and tied into place, the bracing could be removed to make way for the perimeter access road.
Freyssinet’s design solution for the safe unloading and removal of the brace took into account the requirements of the project, including the need to be adaptable, as depending on the weather/live loading conditions the brace could be in tension or compression. The design also allowed for the unloading operation to be halted at any moment and the building left in a safe state in the event of any emergency.
Freyssinet’s final design could accept up to ~100tonnes load in either tension or compression, and from a health and safety perspective, the method eliminated the need for hot works in the airside environment. The solution also satisfied further requirements including:
- Control – ability to release in small (1mm) increments
- Ability to monitor loads during release
- Ability to quickly stop works and mechanically lock system (potentially for weeks)
- Mechanical safety backup and ability to replace jacks in case of hydraulic issues
- Minimum impact/damage to existing/permanent infrastructure
Freyssinet was subsequently appointed to undertake specialist design, supply and installation of the bracing removal system for the temporary bracing installed at the terminal. The sequence of the works included:
- Temporary works design for the cutting of the CHS brace at Heathrow Airport Terminal 2B
- Installation of Exoleaf® jackets
- Installation of clamps
- Pre-stressing of Freyssibar M56 HTSR+ bars
- Installation of transfer structure
- Jacking and load removal
- Cutting of bracing beam
- Removal of clamp and brace
- Removal of main connection steelwork and jacket
Works took place airside at Heathrow Terminal 2B, secured by UK Border Control. Due to the complex working environment and strict security measures in place, operations and the logistical organisation of all materials, equipment and staff needed to be carefully managed. This included:
- The strategic delivery of materials to Heathrow distribution centre for inspection and inventory logging.
- Any plant and equipment could only be hired from ‘airside approved’ suppliers.
- Site personnel required temporary airside passes, which needed to be renewed each week.
- Site personnel were required to go through airport security each day and were escorted at all times.
Effective collaboration with all involved and diligent planning resulted in the safe removal of the brace and a technical project executed successfully.