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Southern Pine Bending Strength
2

Southern Pine Bending Strength

Southern Pine Bending Strength

(OP)
I'm starting to study for the SE exam in October. I don't do a lot of timber design work, so that's my first subject. I'm getting stuck on a simple step in a sample problem. (For anyone who wants to follow along, it's example 4.1 in PPI's 7th edition Timber Design guide.)

Given a select structural southern pine 4x16 beam. What is the value of Fb, prior to any adjustment factors? I read 2850 psi from NDS Table 4B, but the solved example gives 1900 psi. I'm using the 2005 NDS, as specified for the SE exam and in the PPI book.

I found an addendum to the NDS dated March 2013, which revises the value downward from 2850 to 2350 psi. Still no match, although the revised Fc happens to be 1900. (A red herring perhaps?)

RE: Southern Pine Bending Strength

Did you apply all the factors to it? Is it asking for Fb or F'b?

RE: Southern Pine Bending Strength

2
It appears that the 2,850 value that you are using is for a member 2-4" wide. This is a little confusing, but the width is actually the depth of the member as the title of the table is 2"-4" thick. Using the maximum width given of 12" produces the 1900 psi value given. Does this make sense?

RE: Southern Pine Bending Strength

I believe SYP is one of few species that has different values for different sizes. eg Fb_2x4 =/= Fb_6x12

RE: Southern Pine Bending Strength

(OP)
Thanks Crackerjack47, that's exactly where I made my mistake. For a 4x16 member, the thickness is 4" and the width is 16".

RE: Southern Pine Bending Strength

I think all species subject to size adjustment factors actually, aren't they? In any case, the values of SYP were considerably reduced within the past year or two. I first read of it on this site but have seen it confirmed in other sources. So be aware of that and make sure you're using the same values that the testing agency is using.

RE: Southern Pine Bending Strength

A great book that I would HIGHLY recommend for the exam (just having taken it myself) is Breyer's Design of Wood Structures. Very easy to follow and if you read it cover to cover will give you everything you need to know about wood design for the exam (minus experience of course).

If you have any other questions about the exam I'd love to help (without revealing exam material, don't even ask).

Maine EIT, Civil/Structural.

RE: Southern Pine Bending Strength

Not to hijack the thread or anything, but it would be great to start a forum for all things SE related. Then it is a one stop shop when looking for information, questions, etc. while studying. Does anyone agree and if so, who do I contact to get it going?

RE: Southern Pine Bending Strength

Crackerjack, that's a crackerjack of an idea! I hereby second it.

RE: Southern Pine Bending Strength

THIRDED! On engineerboards.com there's a great forum for the 16 hour SE but it's so infrequently used by people that I would have loved to have the expertise of many of the members of this forum while I was preparing for the exams.

Maine EIT, Civil/Structural.

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