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# '97 UBC Element Design

• To: seaint(--nospam--at)seaint.org
• Subject: '97 UBC Element Design
• From: Chris Palmateer <chrisp(--nospam--at)vlmk.com>
• Date: Tue, 8 Sep 1998 11:14:00 -0700

```I was hoping that someone could help shed some light on how to do element
design using the '97 UBC.  Specifically, I'm looking at designing tall
slender concrete and masonry walls.

Assuming zone 3 and soil type Sd for a solid grouted masonry wall, equation
(32-2) yields 0.48 Wp (ultimate load).  When substituting into the basic
load combinations listed in 1612.2.1 (strength design), equations (12-5) &
(12-6) contain the variable E, where E = (rho* Eh) + Ev.  Eh is defined as
"the earthquake load due to base shear, V, as set forth in Section 1630.2 or
the design lateral force, Fp, as set forth in Section 1632".  E is now equal
to 1.0(0.48 Wp) + 0.18 Wp = 0.66 Wp!

Is it the intent of the '97 UBC to design walls for out of plane loading of
2/3 G?  Is this calculated E (=0.66 Wp) then plugged into the load
combinations from 1612.2.1 (multiplied by 1.1 per exception #2) to design
the wall?

This appears to be a substantial increase in design forces from the '94 UBC
(0.66 Wp, ultimate vs. 0.225 Wp, working) unless I'm doing something wrong
(which I hope I am!).  As always, any comments are appreciated.

```