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Re: Retaining Wall Design

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        That is a possibility which I am considering. By my calculation it will take 5x5; but it should work well.  I think just painting the posts would be good enough.
        Thank you for the suggestion.
H. Daryl Richardson
----- Original Message -----
Sent: Sunday, August 22, 2010 5:50 PM
Subject: Re: Retaining Wall Design

Can you "drill out" the wood from concrete, grout in steel tubes (say, 4x4 filled with concrete) and veneer those with wood for appearance purposes?

Steve Gordin SE
Irvine CA

Daryl Richardson wrote:
Fellow engineers,
        I have been asked to design a replacement for a retaining wall that has failed due to rotting of the wood posts after some 31 years.  This sounds simple enough; just install new posts between the existing and replace the planking as required; however, as they say, the devil is in the details.
        The original wall is from 3 to 7 feet high (from grade) and located on the property line between two houses each of which are set back about 4 to 5 feet from the property line.  It was apparently build by a developer who had several such walls to build.  The building procedure appears to have been to excavate a trench about 4 feet wide, build the retaining wall like a fence , then fill the trench in with concrete forming a footing 4 feet wide by 1.5 feet thick mainly under the fill on the low side of the wall.  Alternatively, the posts could have been cast into the wet concrete during the pour; at this time I can not tell the difference.
        The original posts are  6" by 6" actual dimension (not nominal 6x6 timber).  The design works (marginally) for select structural D. fir for strength of posts (based on 1970 allowables) and overturning based on 1.5 safety factor and the dimensions stated based on dimensions observed; but it does not work for current code values.
        The contractor is prepared to build a cantilevered concrete wall utilizing the existing footing (for extra cost, of course).  He does not want to remove the existing footing; he believes this to be the most expensive and time consuming solution of all.
        Given that both owners are retired (hence cost is important), and only the middle half of the entire retaining wall needs replacing, is there a practical way to connect new 8x8 posts to the existing footing in order to recreate the wood wall?
        Thanks in advance.
H. Daryl Richardson