Soldier Beam & Wood Lagging Spreadsheet Check

[jdgengineer]

I was hoping I could get a second set of eyes on a spreadsheet I put together for a soldier pier design to make sure the answers it is coming up with jive with your typical approaches. See attached for PDF output form spreadsheet for both soldier pier design and wood lagging design. The answers seem to be in the ballpark of what I would expect (1.5-2 embedment depth to retained height) but before I start utilizing the spreadsheet I thought a second opinion would be good.

I've based the spreadsheet on the simplified approach of the USS Sheet Pile Design Manual and Caltrans Trenching & Shoring Manual. I'll probably try and retool eventually to the more involved conventional approach, but the answers seem to line up with with a conventional spreadsheet I reviewed against so maybe it's not worth it. A couple of questions:

1) Do you know what the limitations on the simplified approach are? For instance, we often have neglected depths, creep forces, etc. to deal with. Is increasing the embedment by 1.2 still appropriate for these cases?

2) Do you normally consider the lagging to brace the beam? The trenching & shoring manual does, but I'm not sure how comfortable I am with the approach. Although, with the beefy section sizes that are generally picked it doesn't seem to matter a whole lot. I am considering Lb to be the retained height of the wall when not braced by lagging. Does this seem reasonable?

 

[jdgengineer]

I found a slight error in calculating one of the moment arms. See attached for revised.

 

[DaveAtkins]

I did a quick analysis using the "embedded post" method in the IBC, and came up with values similar to yours, with the following comments:

* Your spreadsheet has a value of 2 multiplied times the diameter of the concrete pier--I assume this is because Brohm's method considers using the actual diameter of the pier is too conservative.
* Your spreadsheet uses a value of 0.6 multiplied times the lateral soil pressure on the lagging--I am not familiar with the background for this, but don't disagree that some arching action will occur.

DaveAtkins

 

[jdgengineer]

Thanks Dave. I appreciate the feedback. For your reference, see attached for a couple of pages from the Caltrans Trenching & Shoring Manual which reviews the logic behind the effective width of pier for passive as well as the reasoning for reduction in lagging pressures.

 

[neznajko]

jdgengineer,

Depending how sensitive you are to settlements you may need to check the deflection of the wall.