Wood Shear Wall Software or Spreadsheets 2

[medeek]

For residential design I typically run with segmented shearwalls that I manually calculate and check using the SDPWS-2008. However, I am wondering what if any specialized software or spreadsheets that others might use for looking at shearwalls (segmented, perforated, force transfer) or possibly recommend. What is common practice in this area?

 

[medeek]

Does anyone have a sample wood framed residence RISA 3D file that I can use to test out this software with?

A confused student is a good student.

 

[JoshPlumSE]

Our sales engineers probably have something they could show you if you contacted them directly. I'll try to dig something up later today and post a link, if I can.

 

[CBSE]

@ medeek:

Are you saying complicated because of lack of wall? or complicated because of many vertical irregularities?

Look in the simpson stron-wall catalogs. You can get away with some pretty slender walls using their systems. Just make sure you design the foundation to take it. They also have moment resisting frames that you can either use, or get ideas from.

 

[JoshPlumSE]

Okay, we (RISA Technologies) have got a few resources related to wood buildings:

This first one is a power point presentation that accompanied a webinar on the subject:

http://risa.com/documents/webinars/Wood Buildings in RISA.pdf

This 2nd one is a link you You Tube where you can see the actual webinar:

http://youtu.be/3HTtICAWQ5A

Note:
This webinar is very specifically geared towards commercial wood buildings, not residential. In fact, RISA's implementation is geared much more towards commercial structures. The concepts are basically the same as residential. But, the geometry of residential structures tend to be a lot more problematic. Roof modeling with multiple hips and gables and such is always trickier. Also, you have a lot more discontinuities with residential. Meaning that shear walls don't stack nicely, et cetera.

 

[medeek]

This particular plan has no walls in one direction for about half of the structure. A picture is worth a 1000 words here. I've got to draw it up anyhow. Once I get the floor plan outline at least put together I'll post a screenshot and let everyone weigh in.

The funny thing is the designer told me that even though this particular plan has never been engineered it has been built 5 or 6 times in town and he has never had a problem. Before our new building inspector was hired apparently just about anything and everything flew through their office.


A confused student is a good student.

 

[CBSE]

@ medeek:

An option to also considered is a "3" sided diaphragm if you have no wall on the one side. We use the methodology for hotels sometimes.

 

[medeek]

That is exactly what I'm thinking is going to have to work in this case however looking at the SDPWS-2008 Fig. 4A and section 4.2.5.1.1 the diaphragm length is in excess of 25'. I am probably missing something here though.

A confused student is a good student.

 

[medeek]

Three sided rigid diaphragm?

Note I've tentatively notated where I can get some shearwalls in. The walls are 9ft. high.

This one is going to be fun...

Larger Image

A confused student is a good student.

 

[JoshPlumSE]

Any chance of putting a moment frame in on the side where you can't have shear walls? Or, cantilever columns, or something?

I seem to recall this type of system failing in some apartment garages during the northridge earthquake. Something where the gravity only system on the open side deflected a good amount then P-Delta effects made it unstable and.... collapse.

 

[medeek]

It would be really nice to put a moment frame on the living room wall, that might be a possibility:

A confused student is a good student.

 

[CBSE]

Don't get too complicated, there are solutions:

1) Northwest (plan view) bedroom, use the closet wall as a shear wall. Easy to add in a drag truss.
2) For living room elevations, see attached Simpson product for "Raked Wall Applications" as well as typical shear wall applications.

This house isn't THAT bad

 

[JAE]

This house would typically fall under the IRC in the US.
Note that the northeast corner of the master bedroom violates the IRC in that there isn't a minimum width of wall at the corner. I don't have the IRC handy but typically you can't have a small segment of wall at corners without having specialty details to create adequate hold down at the corner against uplift. The fear is that the uplift load at the corner would overwhelm a single stud pack.

I think the IRC has a table that lists minimum widths at corners.

Of course - if a PE designs out the shear walls then the IRC goes out the window.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[slickdeals]

@Medeek,
Are you a licensed structural engineer?

http://design.medeek.com/admin/license.html

 

[medeek]

I am a licensed PE not an SE.

A confused student is a good student.

 

[medeek]

One of these days I would like to sit for the SE exam however as a practicing PE and running my own small business I have no SE who regularly reviews my work and therefore I do not have a sponsor for the work experience portion of the application.

A confused student is a good student.

 

[KootK]

If you can claim rigid diaphragm without violating any code limits in your jurisdiction, three sided might work. If you go that route, you might consider taking the east and west walls of the living room to make things wicked stiff in torsion and to help stabilize that bit of the living room that juts out north of the rest. Grab CBSE's closet wall for good measure although I don't see that as alleviating the three-sided-ness. If one of the north bedrooms could have it's windows swapped to the side walls, that would be great. I imagine that there's a view being maximized however. Moment frames may well be the way to go.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

I have no SE who regularly reviews my work and therefore I do not have a sponsor for the work experience portion of the application.

I'll do it if it's legit to do so. Frankly, I spend more time working through things with you than my supervisors ever did with me. And don't everybody freak out by my offer. If it's legit to do so.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[medeek]

How come I've never seen the SB shearwall before, I thought I had all of the literature. I'm really liking the chance to grab some shear with one of these on each side of the living room window wall. The ASD allowable shear for wind is pretty decent for a SWSB24x12 = 2965 lbs, but then the red flags come up when I look at the anchor tension at 21685 lbs, wow! My stemwall is going to snap right in two with that amount of uplift. I haven't run my wind loads yet so I don't know what the actual shear is going to be, but hopefully a lot less than the allowable.

I've just ordered a copy of Woodworks and I will put the whole structure into it and throw as many shearwalls in as I can and see what I get. I'm hoping to avoid steel moment frames otherwise my designer will probably fire me.

KootK, I really appreciate your offer and also all of the advice you continually give me with little or nothing in return. I have found Breyer's book and other texts to be very useful in my transition to the structural field however the input and feedback I have received in this forum from a number of individuals like yourself has far outstripped any book knowledge I have gained thus far. In a couple years after I've broadened my horizons into concrete and steel I might take you up on your offer if it still stands. I've been doing residential work for about 8 months now and I've yet to take the training wheels off even for wood, but I think I'm getting there.



A confused student is a good student.

 

[CBSE]

@ medeek:

If you place a shear wall in the bedroom like I suggested, then the uplift on the Simpson walls shouldn't be THAT bad. Test it and see what happens, should be a pretty quick calc.

The Simpson SB walls are relatively new and a fantastic alternative to the steel strong walls. I have had good success and contractors seem to like them a little more so far.

 

[KootK]

It hasn't been a one way exchange at all Medeek. Your adventures have gone along way towards helping me stay current in an area where I don't get much practice. Plus I rip details off of your website.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.