Make this one a group project?
I could see it as a sketchup plan published in 3d so the "reader" can walk through and see joinery details. The fea could be a "movie" of typical loading scenarios. I'd bet it could be interactice allowing the user to input other loadings.
I think as something like that evolves within a large group ideas might start popping up? Then follow the parts that seem to work as a template.

Ken –

My own biased interest in modeling historic framing schemes would be in typical English-tieing. ( if there can be said to be such a thing ) As you know here in New England we are surrounded by this typology, it was the dominate form for just over two hundred years. I can be in a half dozen examples within a ten minute ride. Though here in NNE common purlins, again are dominate, to a degree that could be described as universal, and from early on, the first period through to the late Federal, when English-tieing was finally abandoned, though CP’s survived this transition. I’ve long puzzled and have tried to research as to why CP’s are the dominate roof framing pattern here, having at one time assumed it to be like language and accent patterns on this side, tied to county of origin and migration patterns from your side. Yet as far as I’ve been able to determine it is not tied to any regional framing variation, or migration pattern from one. I do believe it is a successful and symbiotic combination, that redirecting thrust away from the plate makes for an excellent English-tieing frame, and would be interested in how they model in comparison to other historical English roof framing variations

I looked at a potential restoration yesterday, exceptionally fine pre-revolutionary example. ( now I’m really regretting forgetting my camera ) I have restored more than a few and build in this form more often than not.

If you would like to represent a colonial sampling in your project, I’d be happy to provide a survey and photographic / video documentation of an example or two from this corner of the former colonies.

Hi Will & Don,

I think that an idea might be emerging that is worth pursuing and a cross pond design comparison would be an interesting undertaking.

Re common purlin versus Common Rafter

I would surmise that this might have much to do with snow load and I also understand that (Northern) New England can be subject to hurricane force winds that can and does flatten forests.

All of the above and in particular the standard width of a frame might have some significant effect on the roof pitch.

A standard house frame in SE England is one pole wide (16' 6") and I would hazard a guess that a typical standard New England frame like a cape or the like would be much wider. With a steep roof pitch this would push up the ridge height exposing the frame to quite a bit more wind load.

We would need a frame cross section with timber sizes and species. Joint details are not really required at this stage.

Re 3D Models

Producing a Sketchup 3D model is fairly simple. Sketchup will import perfectly from heavyweight CAD programmes such as AutoCAD allowing non CAD users to view and manipulate a model with relative ease.

The demonstration of FEA that is interactive is a bit more problematic and I need to think about how this could be achieved when a recipient is not equipped with the same analysis programmes. I have prepared this kind of thing before for windmills i.e. how they perform in different wind speed and directions but this was done on the basis of preparing a whole series of outputs for a series of fixed inputs and then animating same in a screen show so that variable inputs / outputs could be demonstrated.

It would be nice to hear from the rest of the regular contributors and also some of the TFEC members who do not seem to regularly frequent these haunts.

A digi pic of the two contender buildings chosen to square up in this cross pond match would usefull.

How would we judge the winner ?

Regards

ken Hume

I wrote a reply quite a while ago when the server was getting switched, so it has been lost in the ether. I'm not sure what I wrote, but it was surely poetic and profound.

Ken and Jordan, thanks for the replies.

Ken, so your models do show the buildings surviving? Do you have to tweak the model much to make things work? I don't know how tweakable these particular models are. The models I used to work on were crazy tweakable. Actually in my modeling class we took a real world problem, split the class into two groups and each group produced a perfectly valid model, with two very different conclusions. Hence my initial question and skepticism. And thanks for the enticement on the graduate work, but my previous graduate work burnt me out on homework.

Jordan, as a matter of fact the modeling I used to do was with soil, or really the stuff under the soil. And while the properties of wood may vary by a factor of 2 or 3, the properties of sand may vary by 12 orders of magnitude (like 1 to 1 billion). In general, the geologists would just say this way too complicated, and the engineers would say just take the median and call it in an assumption. The compromise would be stochastic modeling, which could probably be applied to structural FE models pretty easily.

I also like the idea of our cross-cultural tying joint exchange, and would definately support you Ken in your work. What about contacting the Guild or your Fellowship to see if they would be interested in publishing a series of articles or book or something. The SU models would be great as well.

It would be great to hear from more engineers on this subject. It seems as though the Guild is slowly getting through studying and analyzing trusses, chuches, and bridges (the articles seen in the past few years in Timberframing). But I don't know whether those lowly capes and colonials and Dutch barns and so on have been looked at by engineers.

On an entirely separate note...Will, I haven't seen too many English barns in western Mass (although they are certainly around), but the ones that I've seen all have common rafters, and often principal purlins. Again, I'm not sure whether these are just later examples of English barns, or if it's a regional thing. I'll ask Jack. I did ask him whether he had ever seen a historic example of a principal rafter bearing on the end grain of a post (dropped plates I guess you'd call it, as most frames are today), and he said no. Those thing scare me.

Brad