RISA3d Wood Design

[jayrod12]

Good Day Everyone,

I was hoping for some help from the board. Our office currently uses RISA3d for our structural design software for steel and concrete. I am now attempting to include wood design in our models.

Our issue is we are in Canada and therefore design to CSA O86 however RISA3d does not currently support it.

My question is, are there major differences between CSA O86 and the NDS 2012:ASD which RISA currently designs it's members to?

Has anyone else tackled this problem?

Thanks

Jared

 

[TheMoonlitKnight]

That's a tough question - I can't speak to their exact differences. I would think the most obvious difference is the variation of availability and properties of material, i.e. the wood database. I imagine design properties can be different because of the availability of certain woods in Canada. You can sidestep that by creating a custom database in RISA that corresponds to readily-available Canadian wood products.

As far the mechanics, I can't see them being particularly different as all structural design methodologies are based on the underlying physics (obvious, I know). I would bet money that differences arise in the minimums and maximums of properties, e.g. max slenderness allowed for columns, minimum edge/end distances for connections, etc.

The time-dependent stress factor may be different, as well as some of those other environmentally-related factors.

When I switch to an updated code, those are some of the first things I check for - anything that could have subjectivity due to the empirical nature of our practice.

Hope that helps a bit!

 

[jayrod12]

Yes that was more where I was headed.

I am fine with entering a custom wood database to account for differing availabilities and accepted strengths.

My question was more geared towards the actual design methodologies. For example the ks, kt, kh, kzb and kzc factors.

 

[JoshPlumSE]

I think O86 is LRFD based whereas the NDS is still based on allowable stress or service level loads (at least for the most part). Therefore, you can probably expect approximately a 50% increase in member capacity. Offset, of course, by a 40% to 60% increase in the applied loads.

 

[jayrod12]

Thanks Josh,

In discussion with the some of the guys in the office it seems as though that is probably the way to go at least for the time being until hopefully RISA adds the O86 code to the design.

In the end RISA will successfully compute the stresses and we can check those against the O86 design standards.

 

[charliealphabravo]

The O86 Wood Design Manual has a lot of design examples. You could run a few of them through Risa3D as part of a validation procedure.