Should dock steel pipe piles be filled with concrete?

[Jc67roch]

I am designing a dock system for a marina in fresh water (Canandaigua Lake, upstate New York). I am finding that driven, 8 inch diameter steel piles are sufficient for the loadings. However, one contractor is recommending to fill them with concrete to 1) reduce corrosion - from the water inside, 2) add weight to prevent ice on the lake from jacking them upward, under rising water level or waves. Has anyone else run into this? Is this necessary? It is a substance change order to add the concrete. Seems many marina and residential docks around the lake survive winters with solid wood piles(lighter weight, and rougher texture for grabbing).

 

[phamENG]

I've done several piers and a couple marinas. I'm too far south for ice jacking so I've never designed for it. The tension loads from ice jacking should have been included in your analysis, though. Do the pipe piles have sufficient tension capacity to resist it? If so, the added weight isn't needed. Corrosion requires oxygen. Weld a plate on the top after driving to seal it - corrosion will happen, but will stop pretty quickly. I always add at least 1/8" wall thickness above what is needed - often .25" since most of my work is in salt and brackish water.

The only times I've added concrete were for loading (needed the added capacity but I designed it as a composite member), or for impact. Did a large commercial waterfront designed for ocean going vessels and there was a concern that a smaller one might pull up and hit an exposed pile - so we filled it with concrete to prevent a localized pile failure due to an otherwise unanticipated load.

 

[msquared48]

I would. The concrete fill will prevent bucking of the pipe sidewalls from vessel impact.

Mike McCann, PE, SE (WA, HI)