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Re: ASD or LRFD for Wood Design

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Actually, LRFD (USD) design for masonry has not been "officially" included
in the ACI masonry code.  It was supposedly to be included in the '99 code
(at least according to a ACI seminar instructor that I had), but was not

When I ordered by '97 NDS specs for wood, I do recall some mention of LRFD
for wood.  So, the LRFD wood truck is around the corner, and getting up to
full steam to run right in to you!!  ;-)


At 12:40 PM 01/27/2000 -0800, you wrote:
>I saw the thread on ASD and LRFD design and assumed off the bat that they
>were referring to steel, concrete or masonry design. However, yesterday I
>discovered that there is a movement to use LRFD for the design of wood
>structures. At first I thought this ludicrous since wood has a higher factor
>of safety due to the variance in quality on the material. In a discussion, I
>was reminded of the proprietary wood products on the market where the
>materials have much tighter tolerances and much less inclination to
>So, a couple of questions come to mind:
>1. What types of projects will engineers be most inclined to design my LRFD
>2. Considering that framing represents around 17% of the project cost - will
>the benefits of LRFD yield significant savings and if so, in what size
>3. Will this create a more competitive market for proprietary wood products
>compared to the cost of sawn lumber. In other words if the same project can
>be designed by LRFD to maximize the materials - will we start seeing more
>residential structures designed by LRFD so as to use, what some consider,
>better materials at the same cost associated with ASD design for sawn
>As a small office engineer - I have not used LRFD methods. Of course, until
>lately I'd never used rigid analysis for wood structures. Looks like most of
>us wood engineers are getting a real education. Seriously, I would not mind
>the idea of using LRFD in order to use Proprietary wood products like
>Timberstrand which have not been well received because of the cost
>difference. This may make that material more attractive to the home market.
>Any comments or opinions?
>Dennis S. Wish, PE
>Structural Engineering Consultant
>(208) 361-5447 E-Fax