Slide 7 of 13
- TRANSFERRING FORCES TO THE PARTIAL FOUNDATIONS
- Connections are required to transfer earthquake forces into the new foundations and cripple walls
- Unique aspect of a partial perimeter system:
- Connections are required to transfer earthquake forces into the new foundations and cripple walls that are located only at each corner of the building.
- Essentially, each of the four new “L” shaped foundations are isolated from each other and therefore must be connected to the entire length of floor that lies between them to collect all of the forces in the existing floor system.
- With a continuous foundation, this kind of discontinuity does not exist, so none of the special ties and straps shown in the foundation/cripple wall elevations of the partial perimeter system are prescribed in other prescriptive standards.
- Splice must be reinforced with new metal strap
- Along exterior perimeter of the floor, between the new corner foundations, where the ends of two pieces of an existing floor girder are spliced over a post, that splice must be reinforced with a new metal strap nailed or bolted to both pieces.
- Figure shows the new metal strap reinforcement
- Details in Appendix show both bolted and nailed connection.
- The girder is used to drag forces along the edge of the floor into the new cripple wall or foundation at each end of the wall line and the strap provides this load path connection.
- Similarly, where existing floor joists are parallel to the exterior wall, a strap is needed at any joist splice occurring between the two corner foundations.