If you are looking for a strong connection when attaching a timber frame post to a concrete foundation, and one side of the post is hidden, this Simpson STHD Strap may be the the answer you are looking for. The strap gets embedded into the concrete and then is secured to the timbered post with 16d nails.
I have used this connection in several projects, including my home, and the biggest issue will be setting it in the concrete accurately. Your concrete sub-contractor maybe a little nervous at beginning, but with careful layout and measurements they can be installed in the right locations, and are quite easy to deal with.
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