We all felt the January 24th of this year. The 7.1 magnitude quake rocked South Central AK and was felt as far north as Fairbanks and of course felt very strongly here in Homer. Thankfully, damage was minimal and no serious injuries were reported.
TMP AK always knew that our helical pier foundations were suitable for earthquake regions, but there had yet to be a real world test here in Alaska. That changed on the 24th. An unscientific survey of our completed work thus far has given us raving reviews. So far we have not heard of any issues of settling or other damage due to the over 20 seconds of shaking.
We have inspected some finished projects and have not seen any signs of settling, pile movement or drywall cracking. Several houses and cabins on the Kenai Peninsula are fully supported by our piles and seemed to pass the 7.1 magnitude test in January.
While it is known and widely accepted that helical piers preform better than traditional foundations in earthquakes; it is not quite known why. The University of Oklahoma’s Amy Cerato PhD, PE is trying to better understand the science and performance of helical piers in earthquakes. A recent news report report did a story on her study that was conducted in San Diego this winter.
You can read further on her about the study and testing on her blog . She opens her study’s abstract noting:
“After the series of earthquakes in 2011, the city of Christchurch was surveyed and it was found that all buildings/infrastructure constructed on helical piles sustained minimal structural damage, however, a large majority of the condemned buildings were constructed on other foundation types. The international community has qualitative proof that helical piles perform well in earthquake prone areas, but engineers have not quantified “why” those piles are superior foundation elements, and unfortunately, helical pile use in seismically active areas within the United States remains minimal. Therefore, this project seeks to find out “why” helical piles seem to behave so well in seismic regions by subjecting them to earthquake loads in the University of California – San Diego’s Large Shake Table.”
We are eager to see the results of her study and are grateful that these types of studies are being done, not just for retrofit work being done on buildings in CA but for all future structures built using helical pier technology.