Hello!
I was wondering if I could get some insight into a historic post on this Forum please.
In 2012, Jim Rogers the moderator posted: " I used the values for teak of 1950 Fb for Maximum allowable fiber stress in bending. And 1.5 million in Modulus of elasticity. And also, 245 for shear parallel to grain, which is also known as Maximum allowable horizontal shear" (Link at bottom)
I would be extremely grateful if someone knows the source of these very helpful values! So I can understand them better and read around the subject.
The only (less useful) values I've found were from D W Green's 1999 book Mechanical Properties of Wood, Ch. 4.
Thanks!
https://forestryforum.com/board/index.php?topic=62341.0#:~:text=When%20I%20sized%20your%20rafters,as%20Maximum%20allowable%20horizontal%20shear.
Back in those days, I did a design for that fellow FF member.
I consulted with my timber frame experienced structural engineer and he gave me the values as he determined them. Here is his values from my records.
Went through the quick and dirty ASTM approach to adjust from ultimate to design. Assumed "#1" for grade factors.
Table 2. Mechanical properties of teakOrigin | M.C. | | | Static bending | | Compression | Shear | | | | |
| MOR/Fb | MOE | | | | Fc | Fcperp | Fv | | | | | | |
| Phrae PL | 99.3* | | | | 84.0 | 10941 | | | | 36.1 | 7.1 | 12.7 | | | | | | | |
| | | | | | 12183 | 1.6E6 | | | | 5356 | 1030 | 1842 | | | | | | | |
| Phrae PL | 11.4 | | | | 104.0 | 11156 | | | | 53.5 | 9.2 | 16.9 | | | | | | | |
| | | | | | 15084 | 1.6E6 | | | | 7760 | 1334 | 2451 | | | | | | | |
| WH | Green | | | | 11600 | 1.4E6 | | | | 5960 | 930 | 1290 | | | | | | | |
| WH | 12% | | | | 14600 | 1.5E6 | | | | 8410 | 1000 | 1890 | | | | | | | |
| Avg | Green | | | | 11892 | 1.5E6 | | | | 5658 | 980 | 1566 | | | | | | | |
| | | | | | | | | | | | | | | | | | | | |
| Design | psi | | | | 1950 | 1.5E6 | | | | 1400 | 700 | 245 | | | | | | | |
Thanks very much Jim! Super helpful
Hi Jim,
I'm struggling to find information on the ASTM method for converting ultimate to design values. Please may you link or briefly explain how you make the conversions for FC and why you left MOE the same?
I understand that for MOR and FV, you've found a design value 6X less than ultimate which is what Chappell states.
Many thanks
Quote from: fabpilkington on October 07, 2024, 10:03:23 AMHi Jim,
Please may you link or briefly explain how you make the conversions for FC and why you left MOE the same?
Fab:
I didn't do it my engineer did.
I'm doing some research through another engineer who did a presentation showing how to determine strength values.
I'll let you know when I know.
Jim Rogers
Here is a link to a video showing the presentation of how to determine the values of the type of wood you want to use.
https://youtu.be/G0p-pMGUYqQ?si=1hIlP9FLVCgC7_Fn
Jim Rogers
Thanks Jim for that video. Do you know where I could find ASTM D245 (Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber) without the $75 fee?
Quote from: Fred Pilkington on October 09, 2024, 06:55:12 AMThanks Jim for that video. Do you know where I could find ASTM D245 (Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber) without the $75 fee?
No I don't.
Sorry can't help you with that.
Jim Rogers
https://www.astm.org/d0245-22.html
No problem's Jim, thanks for all your help!
@beenthere - *without* ;) :)
Write to them and ask if you can get a free copy.
What is your purpose for using the standard?
You may find a Library that has a copy that you can access.