Seismic Design of Retaining wall - Do you apply vertical seismic action?

[kellez]

Eurocode 8: Part 5 - 7.3.2.2(7) For non-gravity walls, the effects of vertical acceleration may be neglected for the retaining structure.

So for any other type of retaining wall other than gravity walls vertical acceleration should be neglected. What do you guys think of this? what other codes suggest?

 

[kellez]

anyone?

 

[MTNClimber]

The only thing that I can think of is that you could be worried about the wall plunging. I'm 99.9% of the time not concerned with that when it comes to SSP or soldier pile and lagging walls.

 

[Okiryu]

You can freely download this publication:

https://www.nap.edu/catalog/14189/s...alls-buried-structures-slopes-and-embankments

For seismic active pressures in retaining walls, this is shown in page 71:

The effect of vertical seismic loading
is traditionally neglected. The rationale for neglecting vertical
loading is generally attributed to the fact that the higher
frequency vertical accelerations will be out of phase with the
horizontal accelerations and will have positive and negative
contributions to wall pressures, which on average can reasonably
be neglected for design.

I also think that the vertical accelerations do not contribute significantly to the horizontal displacements of the wall so they can be neglected...

 

[jdonville]

I think that you can neglect vertical for most situations. If your wall is supported by piles, however, there might be enough reaction to do a check, especially if the piles are in weak soils.

 

[HTURKAK]

Eurocode 8: Part 5 - 7.3.2.2(7) For non-gravity walls, the effects of vertical acceleration may be neglected for the retaining structure.

So for any other type of retaining wall other than gravity walls vertical acceleration should be neglected.

No...not really..Eurocode 8: Part 5 - 7.3.2.2 item 7 states 'For non-gravity walls, the effects of vertical acceleration may be neglected for the retaining structure.'. That is, it covers the mass of non-gravity wall only! which is negligible....The effects of vertical acceleration for the active soil and resisting passive soil shall not be neglected.. Remember Mononabe -Okabe formula,

Ed =(1/2) γ* (1 ± kv) K⋅H**2 + Ews + Ewd

The item ± kv covers vertical acc.effect.

The picture below depicts the calculation model for gravity retaining wall.. It is clear that , the vertical acceleration affects active soil wedge and wall mass.

 

[Lomarandil]

Kellez, AASHTO also mentions omitting the vertical component using the out-of-phase logic.

----
just call me Lo.

 

[GeoEnvGuy]

Pseudo-static stability assessments use half the PGA or 2/3rds the PGA in the horizontal direction. I recall actually doing both a while ago in a stability program and the effect of using a positive or negative vertical component is much less than the horizontal component.

 

[kellez]

Yes i see what you mean, you only neglect the vertical effect on the retaining structure but not on the active wedge.

 

[r13]

Here is an Eurocode 8 based free program that calculates Mononobe-Okabe earth pressure coefficient for seismic design.

https://eurocodeapplied.com/design/en1998/mononobe-okabe

The problem is the lack of guidance on the design of cantilever retaining walls. Although the "out of phase" argument seems reasonable, but I think the inclusion of vertical acceleration is more prudent practice.