Pole Barn in High Seismic

[WesternJeb]

Hello! I am designing a 60'x40' wooden pole barn with a 16' eave in a high seismic region (SDC D). Seismic loads are controlling my design and the loads are too much for cantilever timber columns alone. We have decided to use "timber braced frames", has anyone had this experience before? We are planning to have the bolts at the connections to be slender in order to increase ductility and have type III / IV connection failure. Since we are introducing some form of ductility into the system, R=1.5 for Cantilever Timber Frames seems overly conservative. My primary question is what R-value seems reasonable here, since there isn't formal guidance in ASCE 7? Thank you!

 

[driftLimiter]

In principle sounds like a good idea to me. But without extensive research its nearly impossible to assign an R-value to a system like this. In my area there are special exceptions for pole barns, so perhaps you could write/draw up some proposed ideas and review it with the building official.

You could look at the ratio of the wood failure limit state to the bolt bending limit state and perhaps gauge what level of additional capacity you have before the wood splits. Assuming that your bolt can be ductile up to this load it seems like a rational approach.

 

[WesternJeb]

Thanks for the reply. Our code officials are usually pretty lenient with this sort of thing, which is both slightly concerning but beneficial in situations like this. That is why I am trying to get a second opinion on an R-value to propose. My plan was either 2 or 2 1/2.

That sounds like a great idea, and would also give myself good a basis for connection sizing to attain ductility. Thanks!