What kind of seismic concrete hold-downs should I use for floor joists over concrete?

Question

Our existing floor joists and decking are over an 8" concrete foundation wall. The new work pictured below extends the existing 2x4 frames for more insulation space and we want to secure the new sill plate and original flooring to the concrete slab for Seismic Zone D (this will also become a shear wall, but thats another story).

• What kind of concrete anchor should be used to tie the old joists as well as the new framing to the concrete?
• If you suggest bolting all the way through from the top of the new sill plate into the concrete, what kind of drill and bit should be used and how deep into the concrete should it go?

Pictured from top to bottom:

1. New framing for additional insulation
2. New sill plate above old decking
3. 3/4" tongue-n-grove solid wood decking from 1951
4. A 2x10" floor joist
5. 2x8" (?) original sill plate laid horizontally (2" showing)
6. 4" of concrete above the garage floor
7. concrete garage floor

This diagram describes the wall:

Answer 1

The wall studs and sill plate should be fastened to the 2x12 joist using tie-down straps. The first picture shows the details (from woodworks.org; the second is the available strap from Simpson Strong-Tie. However, you need to consult with a structural engineer to determine the magnitude of forces the tie and the connection are to experience during an earthquake event.

ADD: For clarification:

Does the sketch below reflect your situation? Please make necessary corrections, which might/will help.

Answer 2

This video recommends using URFP "Universal Retrofit Foundation Plate" when there is not much concrete to tie into.

• https://youtu.be/rfKyrFembH4

Since the shear wall will tie together #1-#5 in the question (with possible additional steel bracing between floor and framing) it becomes one unit for the UFRP to act upon:

Here is an image from the video showing the use either fastening the sheathing to a 2nd mudsill layer and the UFRP below the sheathing edge (left) or through the sheathing into the mudsill (right):

This document suggests that additional bracing is unnecessary in a shear wall if the cripple wall is less than 3-ft; in the original question it is about 11.5":

Here is the UFRP: