Timber Framers Guild Forums Tools Timber Engineering Could someone point me to some math?

Howdy do folks!
Since I'm wanting to reach a bit more towards design, I would appreciate a bit of direction towards some math. Specifically reference materials for calculating load bearing capacity. If this is reaching a bit far, where should I start? I've got a basic ballpark idea of what I'm doing, but I want to fill in some of the gaps that I've been taking on faith from my more experienced co-workers.

There are a few formulas in the back of Jack Sobon's "Build a Classic Timber Framed House". He walks you through engineering a beam or two. It isn't intended to replace actual engineering, just give you a feel for it. I took the Design workshop at The Heartwood School. That is a great course, and will cover the math you are looking for.

Steve Chappell's book has some good stuff, but really, unlessed you're trained and immersed in it, all of the engineering design considerations, bending stress, shear at various joints and points on a beam, load distribution, force analysis, it's often better to design and then hand off to the professional engineer with timberframe analysis experience. Once they do the analysis, they can advise changes, where additional support or sizing is needed, etc. That is how a couple professional framers that do design, do it. Even if you do some preliminary analysis, you ALWAYS want another engineer to check your work. A good engineer is a humble one.

Brad, I'm completely with you. Most of my interest in the math side of things is so that when I hand something off to an engineer there are less changes to be made.

Here in Europe we have the Eurocodes of which Eurocode 5 covers timber construction. Coupled with EN338 (from memory) which provides the resistance values you have all the details required in a dense, almost unreadable format. Basic texts on beam engineering are available online. Search for Euler–Bernoulli beam theory until you find a text that makes sense to you then try worked examples to double check that you've got the maths right. In essence it's not very complicated while you're working on horizontal beams with a support at each end and straightforward loading. Point loads and accounting for the difference between dead loads and live ones start to add complexity as do cantilevers (although the maths is still relatively straightforward). Beams that span multiple supports require a different approach. Basic dimensioning of floor supports like summer beams and joists should be more than feasible if you're just looking to reduce the to-and-fro with an engineer.

Thanks for the direction Jon, I'll see what I can find.

Hi Ghrrum,

To add to all the good advice thus submitted, I would suggest trying to find the closest PE that works with timber framers and/or the TFG and have a discussion.

For those of us that have been doing this a while, I can say that your desire to "front load" your own math is admirable and good practice. It demonstrates to a PE that you are really making an effort to design well. Also understand that "engineering" a living material like wood is as much an art as it is a science...and "the math" is based on charts that are in turn based on averages in a spectrum...None of this is "hard fact" but "good guess."

I would also suggest a lot of "field study" with as many Master Timberwrights as you are able to find, and also study dendrology, botanizing, traditional vernacular building modalities as they apply to timber frames in all disciplines...not just one, as well as take a timber grading class.

Good Luck,

j