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Re: ACI 530 Masonry ASD

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William,

	We had similar problems when we began introducing strength methods of
design into Canadian codes some years ago so I can understand your
frustrations.

	I hope no one will take offense with this obvious (and probably
unnecessary) caution because no offense is intended.  Be sure you don't
use BOTH load reduction factors AND increased allowable stress for some
load combinations;  this would be doubling the intent of the new code.

				Best regards,

				H. Daryl Richardson

Sherman, William wrote:
> 
> ACI 530-99 has some rather confusing provisions within Chapter 2, Allowable
> Stress Design. An engineer in my office asked me why "strength reduction
> factors" are being applied under allowable stress design - based on Section
> 2.1.1.2.3.3. It took me a while to figure it out, but as far as I can tell,
> Section 2.1.1.2.3 seems to only apply to "strength design" even though it is
> in the "Allowable Stress Design" chapter.
> 
> Section 2.1.1.2.3 states that this section only applies for masonry "not
> designed in accordance with Section 1.1.3". Section 1.1.3 requires masonry
> to be designed per one of the given Chapters, including Chapter 2 for
> Allowable Stress Design. So if you are not designing in accordance with
> Chapter 2, this subsection of Chapter 2 applies - Huh?!
> 
> I assume that the intent is that if you are not using allowable stress
> design per this code, then you should use the ASCE load factors and given
> strength reduction factors. Unfortunately it does not explicitly say this,
> and it is very confusing talking about "strength design" requirements in a
> chapter on allowable stress design.
> 
> Has anyone else tried to apply this code to allowable stress design of
> masonry? Is my interpretation correct?
> 
> (Note: The next revision for this code is currently out for public review
> via the ACI website or www.masonrystandards.org, but this section has not
> been clarified in the proposed revisions. If someone can help me understand
> the intent, I will send in comments to clarify this document.)
> 
> William C. Sherman, PE
> Camp Dresser & McKee, Inc.
> Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
> 
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