Loading Dock PEMB Foundation design

[JC2021]

I am doing a foundation design for PEMB with a loading dock. Building is 150' by 65' with the truck dock in the 65' end wall. Frost protection is 3' below FFE and the loading dock bottom will be 4' below FFE. I assume this means that I need to extend my foundation wall in the area of the loading dock an additional 4' down to protect it from frost heave in the area of the loading dock, but how is this typically done?

1. Do you just extend the foundation down in the area of the loading dock, or do you make that whole wall down to that depth?

1a. If just in the area of the loading dock, how far past the edges of the dock should I extend the deeper foundation wall and is there additional reinforcing required other than what is standard for the wall?

2. I thought about using XPS under the base of the loading dock so that I didn't have to go as deep, but suspect that it wouldn't hold up under the load of the semi. Has anyone had success with this?

Also, potentially of note, the PEMB designer set up the dock as an expandable end wall so that there are no load bearing columns in the wall with the truck dock, so I'm not worried about any building loads being transferred .

Thank you

 

[jayrod12]

You can get insulation with the load carrying capacity required for semi loading. Hockey arenas employ this regularly. Check out Hi-100, which is rigid insulation with a allowable compressive capacity of 100 psi.

 

[HTURKAK]

Building is 150' by 65' with the truck dock in the 65' end wall.

You did not mention the size and position of the loading dock . If the corner columns are not affected , i would prefer to extend the perimeter grade beam with continuous ftg just under the dock level . The end wall columns primarily wind resisting and no need to provide the footing similar to the main portal frame ftgs.

 

[JAE]

The key for me is to always ensure that any footing bearing surface is at least X distance away from "air" where X is the required frost depth.
So this would include diagonal or even horizontal distances from footing to air.