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RE: seismic at retaining wall

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Sounds like a problem on my PE exam except there was a hurricane blowing on
the wall.

Braja M. Das "Principle of Foundation Engineering 2nd ed." chapter 5.11 and
5.12 has formulas for determining seismic active and passive pressure if the
soil internal angle of friction and seismic acceleration are known.

Surcharge should be included additional pressure that is multiplied by the
earth pressure coefficients.

Scott M Haan  P.E.
Plan Review Engineer
Building Safety Division, 
Development Services Department,
Municipality of Anchorage
phone: 907-343-8183   fax: 907-249-7399

> -----Original Message-----
> From:	Novak, Dan [SMTP:DNovak(--nospam--at)]
> Sent:	Tuesday, March 20, 2001 7:13 AM
> To:	'seaint(--nospam--at)'
> Subject:	RE: seismic at retaining wall
> I was watching for this also, however as you know there are several
> options.
> I know of one engineer that includes the seismic mass of everything, and
> the
> soil.  I generally will design for the seismic mass of the soil if
> recommended by the agency or in the geotechnical report.  I will always
> design for the wind or seismic load on any projection or fence.  As I
> understand Caltrans is currently establishing some criteria,  however the
> existing criteria identified in the standard plans requires no seismic
> design for retaining walls.  Any sound wall or fence on a bridge or
> retaining wall is designed for wind and seismic loads. 
> Dan Novak
> -----Original Message-----
> From: Mark Pemberton [mailto:Markp(--nospam--at)]
> Sent: Tuesday, March 20, 2001 7:56 AM
> To: 'seaint(--nospam--at)'
> Subject: FW: seismic at retaining wall
> I got no response from this so I'm resending.  I'm
> sure others have been faced with this...
> How would you analyze a retaining wall that extends
> to form a 10 foot high masonry fence for seismic forces?
> With a parking lot at the retained side, would the surcharge
> load need to be included?  What weight would you
> use for the seismic mass? (Fence portion or the wall
> in its entirety?)  It seems there are several ways
> to look at it and all yield somewhat different results.
> Mark Pemberton, P.E..