Retaining Structure Subjected to Seismic 3

[PEStruc]

Should we add the seismic forces due to own weight of seismic structure (Eh and Ev) to the dynamic seismic earth pressure force when we check the stability, especially if the own weight is significant? The used method for determining the dynamic seismic earth pressure is Mononobe-Okabe. Any good reference talks about this.? Appreciate the help!

 

[HTURKAK]

Yes you are expected to add the seismic forces due to own weight for gravity walls and semi gravity walls. Moreover you shall consider the vertical EQ effects..

The picture depicts Force Diagram for the Cantilever Retaining Wall. ( taken from NCHRP REPORT 611 which is good reference )

 

[WARose]

I think a good reference for this is 'Principles of Soil Dynamics' (2nd ed, by: Das & Ramana). Bowles has a good section on it too.

And by the way, I'm not sure what code you are using, but ASCE 7-10 (for example) doesn't require this until you get to SDC D (or higher). So you may want to check and be sure this is necessary as per the code you are using.

 

[ATSE]

The M-O method does not work (gives unreasonable values or no solution at all) for high kh and sloped backfill.
Limit equilibrium is an alternate for medium-tall walls.

 

[dik]

Your reference document is excellent.

Dik

 

[PEStruc]

Just found that the vertical seismic component can be neglected and set as zero if alternative load combination is used per IBC 1605.3.2

 

[Lomarandil]

Many M-O methodologies allow the vertical seismic component to be reduced or neglected (due to out-of-phase behavior)

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just call me Lo.