ductility (also related to your confidence in material values). If stick
framing/plywood/nails is 6, I sure wouldn't be using 6 for adobe,
haybales, heavy timber, etc.)
Chuck Utzman,P.E.
Gordon Goodell wrote:
>
> For those of you who deal with heavy timber construction and
> traditional timber framing, what response modification & overstrength
> factors do you use?
>
> More globally, when you get into weird or new systems that aren't
> listed in ASCE 7 Table 12.2-1, how do you deal with it? In many cases
> you could pick a similar system and decide if the factors listed for
> that system are reasonable for yours, but when you're talking about
> ability to perform into the plastic range it's a lot about confidence,
> and a lot about having seen how these systems have survived real
> earthquakes. If you were designing the world's first stick-framed
> house, how could you quantify ductility and overstrength? You could do
> it for the materials in a lab, and then try to extrapolate those data
> to your framed system as a whole, but you're not just talking about
> wood...it's also steel, interactions between materials at connections,
> etc. Think about how hard it is to calculate the deflection of a wood
> diaphragm...the assumptions overwhelm the results long before you've
> got a number to hang your hat on.
>
> So what about straw bale houses? Adobe? Rammed earth? Earthships? What
> do we do, say "I have no data for or confidence in the system, so I'm
> going with R = 2"? For straw bale construction, I've seen engineers
> use values ranging from R = 2.5 to R = 6. It makes a big difference!
>
> Just wondering how any of you deal with this if & when it comes up.
>
> regards,
>
> Gordon Goodell
>
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