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Re: Wood design values for old structure

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ASTM D143, D245, D1990, 2555, and D4761 are the appliable standards.

ASTM D143 is one of two basic mechanical testing Standards for wood in North America when the goal is to develop estimates of properties for structural design. ASTM D143 tests small clear (knot- and defect-free) specimens then modifies the clearwood properties and their variability to estimate the 5th percentile of clearwood property then further account for the effects of knots, slope-of-grain, density, and grain orientation (flat-, quarter-, or bastard-sawn). With flat-sawn lumber the growth rings are parallel to widest face. With quarter-sawn lumber the growth rings are perpendicular to widest face. With bastard-sawn material there is NO control on growth ring orientation. Bastard sawn most accurately reflects actual production lumber. ASTM D245 instructs the user how to use D143 values to derive allowable design stress (ADS) values. ASTM D4761 is used when testing production-sized lumber and timber. ASTM D1990 instructs the user how to use D4761 values to derive ADS values. Both methods are used to derive allowable design stress values in North America. Most hardwoods use the D143/D245 methods, most softwoods use the D4761/D1990 method. The former was used from 1934-1990, while the latter is now the preferred way.

Consider a 3-point flexural test method.

see the proceedures listed at:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm ch6

http://www.fpl.fs.fed.us/documnts/pdf1997/green97a.pdf

http://www.wwpa.org/ TN4 and TN5



Bruce Holcomb <bholcomb(--nospam--at)brpae.com> wrote:

We are looking at a building built about 100 years ago in SW Missouri and are wondering what strength values we can use to analyze the wood framing.  There is a lot of Oak in this area, so the framing may be Oak (that was once somewhat common), but other likely species we might encounter would be Doug-Fir, Southern Pine, D-F-L and S-P-F.  Does anybody have any values for old wood we can use for analyzing the joists, beams, studs and columns in this old structure?

 

 

Bruce D. Holcomb, PE, SE

Structural Engineer & Vice President

Butler, Rosenbury & Partners

319 North Main, Suite 200

Springfield, MO 65806

417-865-6100

417-865-6102

 


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