Rebar Case Study - Commercial Project

SOLUTION PROVIDED BY PGT:

1. Understanding the technique of Top-Down construction:
The top-down method has been used for deep excavation projects where tieback installation was not feasible and soil movements had to be minimized. Construction sequencing plays a vital role, as we need to maintain the connection between elements according to the construction schedule. Regular discussions with the client on construction activities and future work help significantly.

02. Understanding the importance of propping:
Due to excavation, soil movement increases, and properly designed props are required to resist lateral forces, ensuring excavation continues without disruption. In other words, props are needed to support both the existing structure and the new structure at ground level, such as capping beams.

03. Temporary work - Corbels:
Corbels are required so that propping can connect with them. However, since the corbel is temporary work, the structural engineer is not responsible for designing it. This falls within the scope of the site team. Therefore, in the event of a clash between the corbel reinforcement and the capping beam, we worked out a suitable combination and proposed a conservative option in the form of an RFI to the client.

04. Tube tunnels under the south side of Crescent:
This is a significant challenge for the site team due to the close proximity of the tunnels, which also creates noise and vibration issues. These will be mitigated using an acoustic anti-vibration isolation system. However, detailing was affected due to frequent changes in requirements based on site conditions. We maintained logs to keep track of these changes.

05. Prefab requirements of the client:
As a fabricator and placer, the client preferred prefab work. We thoroughly studied the requirements of all prefab elements (through site visits and one-on-one discussions with the client) and trained the team accordingly.

06 Limited working hours for site activities & limited space for material storage:
As the site is in a prime location between major London landmarks, such as Lords Stadium, Buckingham Palace, Tower Bridge, Madame Tussauds, and Oxford Street, there are many restrictions on construction activities, including daytime working hours and noise levels. Day-to-day and effective coordination with the client’s schedule, along with proper planning of our activities, is the key to managing such conditions.