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.