We were recently approached by a Client whom we had worked with back in 2007 on a building in Christchurch. Unfortunately, the super-structure was one of the limited few of around 100 structures on our piles that had suffered in the series of earthquakes. The extent of the damage was such that it was not economically viable to repair.
However, the Engineer noted that the building had been designed to over strength loads and saw that there may be value in the on-going capacity of the existing screw piles as part of the planned new building.
Having completed a desk study around the proposed new building loads in accordance with the latest version of code requirements, combined with our archived pile manufacture and installation records and on site load testing, we felt that there was a possibility of re-using the piles.
Subsequently, a pragmatic approach by our in-house engineering team, in discussion with the structural Engineer, recommended that the piles below shear walls be removed for inspection. This was a unique opportunity to view piles that have been in the ground for over six years but more significantly subjected to substantial seismic events.
The results to date are encouraging:
- No deformation of helices
- All welds NDT tested - no defects
- Shaft – true with no permanent deformation
- No corrosion – even in upper pile above the water table
The future use of the remaining piles is still under investigation, with further destructive tests to the extracted piles. However, this unique opportunity has given us some validation that the many subtle aspects that we demand in the delivery of quality screw piles, results in surety to our Clients. The proof is in the pudding.