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Seismic Retrofit Questions

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I am in the middle of an investigation of an old school in my area.  The
main concerns are with seismic safety, although in the process I've found
other problems.  I'm not in the process of doing calculations for an actual
retrofit, but my findings will be used by the school officials to help
decide the future of the school.  At the moment I have two questions to pose
to the list.

In the oldest portion of the school (5 additions since the early 60's) there
are some load bearing masonry walls.  Checking the walls for load
combinations in UBC (sorry guys using WS design) I have found that the
reinforcing provided in the walls is adequate strength wise although
severely lacking in minimum reinforcing requirements for a zone 3 structure
if it were being designed today.  I am at a loss as to how to approach this
in the report.  Do these walls need an upgrade in capacity in some way, or
not.  I'm sure I will be pressed on this matter.

Another question was posted in a similar situation last June, although I
think I remember the metal decking wasn't required as a diaphragm.  In this
school (a newer addition) steel joists were used to support metal decking.
There is no direct connection from the diaphragm to supporting CMU walls
below.  I will be looking for supplying shear transfer from the deck to the
walls, hopefully without disturbing the roofing membrane which is fairly
new.  Back in June Stan Caldwell listed some molly bolts with a supplier in
Denver, although the bolts had no ICBO certification.  Does anyone have any
ideas for an attachment of this sort.  Angles installed below and attached
to the deck from below?  The school district is low on cash, Just built a
new high school, so cost is an issue.  Also, the community has become very
aware of the issues, and it would be nice to have the ICBO thing or
something substantial to be able to back up the method used.

Thanks, Joseph Grill, PE



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