Cantilever Sheet Pile Wall With Wind Load

[ChiEngr]

Hi Everyone,

I am working on a project in which we are to install a cantilever sheet pile wall as per the attached. The wall occurs next to a body of water. I have performed the design of the wall accounting for all lateral earth pressures and hydrostatic pressures. The one thing I am struggling with is the inclusion of wind loads on this structure. The wall continues above grade about 4' and a 7' tall chain-link fence is applied on top of this. I have designed a channel cap to span along the top of the wall so that the wind loads imposed by the fence posts load the wall relatively uniformly along the wall's length. In terms of analysis, are there any techniques which are commonly used for this condition? I am trying to not go beyond the pile depth shown, and am near capacity on my pile design. I just don't know if the wind load will control given the amount of soil being retained. I am assuming the traditional ASCE7 load combinations apply as per usual.

Any help or feed back would be greatly appreciated!

 

[PEinc]

If you haven't designed the wall yet, how do you know that the SSP tip is at EL. -43.5? Assume the exposed height of the wall is 21 feet. Draw your wind pressure on the back face of the 11' high fence. Assume the embedment is D, an unknown. Sum the moments about the tip of the SSP assuming the passive resistance will provide moment equilibrium. Solve for D. Multiply the calculated D by at least 120% and calculate the tip elevation. Take the derivative of the moment equation to get the shear equation. Set shear equation to zero and find point of zero shear. Plug the zero shear D value (not the 1.2D value) back into the moment equation to calculate the maximum moment in the sheet pile. Maximum moment occurs at the point of zero shear which will be below your grade in front of the wall. This design will be easier to do in allowable stress, not LRFD. Is your retained soil height 10 feet or 10.24 feet?

http://www.PeirceEngineering.com

 

[Settingsun]

Not sure about ASCE 7, but often there's a combination factor that reduces the live load (surcharge) when combined with wind load.

 

[DaveAtkins]

The appropriate ASD load combinations from ASCE 7 would be:
H + L
H + 0.6W
H + 0.75L + 0.75(0.6W)
where
H = lateral earth pressure
L = lateral earth pressure due to surcharge
W = ultimate wind load

Most of the time, H + L governs. Wind is generally not a concern with sheet pile walls, because nothing is exposed to the wind above the upper grade (and as far as I know, nobody bothers to check suction on the wall itself). But you have an unsual case, where the fence is actually taller than the cut.


DaveAtkins