If you would like to know more about the brand new state-of-the-art seismic retrofit guideline, there are around 30 educational videos and web pages that you will find interesting. Just type ICC 1300 in the search box in the upper right.

This video is an in-depth look at Detail 4, Sheet D1 found in the seismic retrofit guideline ICC 1300 Vulnerability Based Seismic Assessment and Retrofit of One and Two-Story Dwellings

It looks at a unique method used for foundation bolting in seismic retrofits.  The conclusion of this video is that this detail is an unnecessary part of ICC 1300 and only undermines its credibility.  It reveals that the committee members who wrote this guideline have never confronted this engineering challenge it tries to solve in a practical way.

If you look at the detail carefully you will see where it says “Embedded foundation sill where occurs (shown dashed)” the solution is to put a block on top of the sill, forego attaching the block to the sill, then put a block on top of that.    Working with concrete embedded sills is quite common in foundation bolting in seismic retrofits.  In older homes, wet-set sills where sills are intentionally pushed down into the wet concrete are the rule rather than the exception.   This way sills could be adjusted to make sure they were level.


Poor alternative to foundation boltng

This particular detail is being recommended because, in the mind of the engineer who drew this detail, the Type A Simpson URFP Connector cannot access the side of the sill because the sill is embedded in concrete.  Any contractor with minimal experience with tools knows this is not true

Foundation Bolting In Seismic Retrofits Made Difficult by Concrete

For decades contractors have been breaking out concrete like this with a hammer or air chisel.  Concrete and wood have poor adherence and breaking out the concrete is easy to do.  Recommending this expensive alternative will, unfortunately, undermine the credibility of Vulnerability Based Seismic Assessment and Retrofit of One and Two-Story Dwellingsin in the eyes of contractors.  Contractors will rightly assume anyone who recommends this way of doing this is out of touch with the practical reality of seismic retrofit work and the tools contractors work with every day.

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