Timber piles in high seismic region
Timber piles in high seismic region
(OP)
Got a project in Washington State in a high seismic region with timber piles. Have read some areas that do not allow Timber Piles in California due to concerns with ductility. Also, have read articles recommending embedding piles a pile diameter into cap for ductility. Anyone doing timber pile projects in that region? A 2 to 3 inch pile embed may be too shallow for a maximum seismic event. Would you design the timber piles for the design seismic load using the R of the system or consider changing the R value for checking the lateral load on the piles? The passive pressure given by the geotechnical engineer is not helpful only 75 pdf/ft.






RE: Timber piles in high seismic region
The minimum embedment here that I have used for 40 years is 6" regardless of the diameter. It locks the pile into place from walking due to seismic action, and protects the end of the pile. I uesd the R value for a cantilever pole system.
I did a house on pile of varying lengths above ground several yuears ago in LaConner, Washington, that is still doing well. Just proportioned the lateral load to the pile based on the flexibility so the system was tuned to the response. Worked fine in the last event in 2001 here.
If you have to, consider using batter pile to take the lateral.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Timber piles in high seismic region
RE: Timber piles in high seismic region
For your application, with lateral values that low, I would definitely use batter pile.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Timber piles in high seismic region
RE: Timber piles in high seismic region