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RE: 1997 UBC Masonry Wall Design

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Bruce -

> Bill -
> Three comments.
> 1.  Is it OK to average the loads for the wall design, or do
> you have to use
> a triangular loading for the wall?

Heck, I dunno. I didn't write this bleeping code!!

FWIW, the distribution is trapezoidal, not triangular. There is a force at
the base.

I did use the average to design the wall section, but I used actuals to
determine the connection at the top.

BTW, this makes sub diaphragm design a lot of fun, particularly when I
include 0.545g of the mass of the roof times the depth of the sub diaphragm.

I'm having to put in collectors at 16 feet on center!!

>  This could effect your
> top connection
> design by quite a bit.

But, we don't want to underdesign in case there is an "expert" witness out
there somewhere, do we?

> 2.  In many areas of Southern California, the Na factor will
> be 1.3, causing
> your seismic factor to jump to .442Wp, which is significantly
> more than the
> 0.3 required by the old code.

Yeah, Na is 1.3 on my project. I excluded this for comparison purposes.

> 3.  What are your getting for a coefficient for your parapet
> design as
> opposed to the old Code?

It is large.

It varies from 1.362 at the roof level to 1.456 at the top of the parapet,
including Na=1.3.

!.5g! This parapet ain't going anywhere!!

I think it's about time to retire.


Bill Allen, S.E.
Laguna Niguel, CA