hi David,

I don't want to get too far away from TCB's queries and topic line of his "concepts" of a double wall system... I will cover some points of clarification then leave it be for TCB continued questions...




Actually it very much is in the "oblique bracing" category of systems. Agreed it is perhaps one of the best, oldest and most functional of these systems, however any time there is the formation of a "canted system" that does most of its work..."in compressive"...loading, then it is considered and "oblique system" from an engineering viewpoint, no matter how slight the angulation may be or the relative size of the bracing modality itself.


Even the the broad range of "Riegelbau" bracing systems are variable...they are "slanted" and do work in a compressive loading condition for most of their work in the architecture. They do this marvelously because of their larger size, and "sill to plate" formating. They still are in the "oblique system" as they are a...



And this does indeed...from an engineering perspective (having discussed this numerous time with my own PE I work with)... form a "triangulated system" of compressive resistance, which is the primary function of most of the working systems within the "oblique bracing" modalities...Again, this is one of the best because of the large "slanted" (aka bracing) format, its "buttressing effect" and "sill to plate orientation."

I would further add in support that, indeed the older styles (and larger) "oblique bracing" systems did have some limited work capacity in "tension" bearing capacity. This does not change the primary "work force" of these systems to do most of there function in a "compression resisting" format, as "let in" bracing..."strengthening"...in the tension format was not the primary function, nor has this been bore out in any of the historic research of merit that studies these vintage systems and the application to the architecture...

I more than agree that most contemporary or "standard oblique bracing" primarily "only works under compression" and offers virtually no "tension effect" within the frame...I would have to challenge that the "dovetail joints" of any of the let in systems "works well in either direction." Some yes...but this system is still primarily a compressive system not a tensioning one, though agreed it offers a limited capacity in that regard much more so than the shorter "stub tenon" methods of a standard brace system we find today...as these "stub tenon" oblique bracing systems historically in some region do not even have pegs at all..Some are simply "well fitted" and/or "wedged in place" after raising further facilitating "tightening" at a later date by more pressure added to the wedged mortise. The ones that do have pegs in their small tenons do little work beyond holding the brace itself during raising...Unlike the "dove tail" which does indeed do "more work" when well executed and better pegged/wedged...

I would offer that of all the systems found in Europe the longer "pass through" (or by) bracing of the Swiss and French systems do the "most work" of all the "oblique systems" of bracing we find in European designs. I would not disagree in either of these recommended modalities, though the are not the only "simple systems" that exist historically in timber architecture...

I would not go beyond this level of discussion detail further so as not to distract from TCB's post topic, and perhaps take this offline if there is a need to explore any details further about "bracing systems."

Regards,

j