Residential Engineering with RISA3D

[medeek]

I think it would be interesting to try and use RISA for some of my residential jobs. I currently using Woodworks Shearwall software to help me analyze the lateral loads and how they get distributed to the shear walls. I am wondering if this sort of thing is possible in RISA. I'm getting a handle on how the wall panel features works but my biggest problem seems to be with how to model the roof (typically sloped, gable or hip) and have the program distribute those forces into the shearwalls.

I'm very new to RISA so I'm wondering if I am trying to make the product do something it was never intended for, has anyone had any experience doing this sort of thing. I am also looking for tutorials on modeling residential wood structures specifically.

A confused student is a good student.
Nathaniel P. Wilkerson, PE

http://www.medeek.com

 

[JoshPlumSE]

When we made our big push into wood structures a few years ago (with some encouragement from the Wood Products Council), we focused mostly on commercial wood structures. So, residential wood wasn't a direct consideration. That being said, much of the features would be common between the two types of structures.

This includes the following:
1) Wood wall panels
2) Better treatment of engineered wood materials
a) Paralams / Versalams, et cetera
b) Wood I-Joists (in RISAFloor)
3) Better optimization lists for various wood materials.
4) Expansion to include Canadian codes.
5) Flexible diaphragms (when working between RISAFloor and RISA-3D)

But, where residential starts to become difficult is when the roofs and diaphragms geometry starts getting really complicated with openings and hips and gables and such. There isn't a great solution to that problem. If you distribute your lateral loads manually based on flexible diaphragm theory there isn't much of a problem because you enter then as you would any other loads. But, if you want the program to perform a semi-flexible diaphragm analysis then things get pretty complicated. It should be possible, but it's a lot more complicated than most people want to do.

 

[Guastavino]

Medeek,

With wood I don't think much beats the pencil and paper method, but RISA can help in the wall design and individual elements. I haven't used the wood design wall panels, but I have used the masonry ones. It's a big time saver on that, and I assume the same for wood. Also, RISA is really easy to use and their tech support is second to none. I can call a toll-free number, a human picks up, and then I talk to a professional engineer. Or I can email them and they get back to me usually the same day.

Josh, correct me if I'm wrong, but I've used RISA-3D to analyze a bunch of members in the same model that are all independent. I just give the Section set name my convenient tag such as "Beam 1". Then I give individual supports. RISA-3D doesn't seem to care that I have another beam 10' away that is connected in no way shape or form. That way you get a design check on everything by setting up one set of load combinations etc.

I don't work for RISA or get kickbacks, I'm just a satisfied customer. I will say though, like any engineering software, RISA isn't perfect. I've found at least two mistakes in their software. However, they admitted them, they were minor, they fixed them, and they were helpful in getting things resolved. Point is, make sure you double check your calculations until you get comfortable with them, but I think RISA is great for wood design.