Wood Shearwall with Openings
Wood Shearwall with Openings
(OP)
My question is in regards to wood shearwalls with openings. For a typical shearwall I would use the Segmented Shearwall Method using only strips of wall the are not at the opening. I have attached an example calc. (first page).
That example is for a shorter rectangular shearwall. The problem I am running into is shearwalls on the other sides of our building the continue up to the pitched roof. If I use the segmented shearwall method, it would look like the second page attached. These are simplified examples of what we truly have and if I use the segmented shear wall method on a wall this high I start to get really high hold down values with our true loads. Also, our h/b aspect ratios start pushing the limit or beyond. It seems like there is a lot of wall above the opening that should be used.
The third attached sheet is how my boss has done it previously. It is not an actuall method I have found and I'm not completely sure it is legitimate. I guess it is a variation of the Segmented Wall Method. The first segment being down to the opening as shown attached and finding the Tension and Compression reaction of the extreme outside. Then these are added the the outsides of the individual walls below. As seen in the results, I'm not sure if the interior reaction are as high as they truly should be.
Does anyone have any suggestions. I could try to use the Force Transfer Around Openings method, but not looking for something that complex. Does anyone have a recommendation on how to handle a shearwall that looks like the second attached page? All the examples I have found are for shear walls that look like the first page and I can't find anything to support the calculations shown on the third page.
Also, has anyone tried modeling a wood shear wall as a plate with appropriate properties in a FEM program and then pulling the shears and reactions from that? Does anyone have any objections to doing it that way?
That example is for a shorter rectangular shearwall. The problem I am running into is shearwalls on the other sides of our building the continue up to the pitched roof. If I use the segmented shearwall method, it would look like the second page attached. These are simplified examples of what we truly have and if I use the segmented shear wall method on a wall this high I start to get really high hold down values with our true loads. Also, our h/b aspect ratios start pushing the limit or beyond. It seems like there is a lot of wall above the opening that should be used.
The third attached sheet is how my boss has done it previously. It is not an actuall method I have found and I'm not completely sure it is legitimate. I guess it is a variation of the Segmented Wall Method. The first segment being down to the opening as shown attached and finding the Tension and Compression reaction of the extreme outside. Then these are added the the outsides of the individual walls below. As seen in the results, I'm not sure if the interior reaction are as high as they truly should be.
Does anyone have any suggestions. I could try to use the Force Transfer Around Openings method, but not looking for something that complex. Does anyone have a recommendation on how to handle a shearwall that looks like the second attached page? All the examples I have found are for shear walls that look like the first page and I can't find anything to support the calculations shown on the third page.
Also, has anyone tried modeling a wood shear wall as a plate with appropriate properties in a FEM program and then pulling the shears and reactions from that? Does anyone have any objections to doing it that way?






RE: Wood Shearwall with Openings
However the usual case is a flat ceiling with ordinary gable truss bottom chord bearing on the end wall (platform framing) - in that case, the the truss transfers the shear to the top of the 2 shearwalls at a height of only 16', and I specify the drag load of the truss on the drawings. (as in most wood buildings)
RE: Wood Shearwall with Openings
You mentioned you have used the third page alternative method for a case like this. Is this an actual method? It is one way I was shown how to do it, but can not find any reference to doing it this way. It is not exactly the Segmented Wall method, but I think it is the closest to the three methods I know of. One of the other methods I know of is "Shearwalls designed for force transfer around openings". This method looks more complicated then what we are looking for and we don't want to get into the straps and blocking. The other method I know of "Perforated Shearwall" I understand to be more empirical and will have a lower allowable load.
If I continue to analyze the wall like the third sheet posted, is the any moment that is not being accounted for being transered from section 1 to sections 2 and 3. Can I just find an internal reactions at the ends like I have done between the segments and add that in to the true reactions for segments 2 and 3?
RE: Wood Shearwall with Openings
Also, is the entire end wall sheathed with WSP, clear up to the roof?
What I meant to say is we were doing this before the Code even mentioned this topic (as far back as 1974), and it is not mentioned in the Code to date, just something that someone proposed at a seminar and we gave it a lot of study.
The Code allows us to do certain things - it's our engineering judgement. We can design everything with Simpson HDU14's but that would hurt our future business.
RE: Wood Shearwall with Openings
The third sheet is the method my boss has done for years (he has owned the firm 30 yrs.) so maybe he came up with that the same way you did. I hadn't seen it done like that and questioned it, so he wanted me to track down if that is a legitimate way to do it or not and if the code allowed its use or not.
Thanks for the input. Also, we are having to use HDU14 or HDU11 hold downs already even using the method on the third sheet. Our transverse shear walls kept getting smaller on us due to additional openings on a long nave so we end up with a decent load on very short walls. The attached sketches were just simplified versions to get the idea across.
We have shearwalls at the ends of the building, but due to the length and transition between spaces, we have short transverse shearwalls in the interior of the space as well.
RE: Wood Shearwall with Openings
You mentioned "just something that someone proposed at a seminar and we gave it a lot of study"
I know that was a long time ago, but do you still have that seminar information or know where to find it. Or any other similar references. The best I can come up with is the regular segmented method. If we end up using that, like the second sheet I have posted, our tension and compression loads are going to be crazy high once we put our true higher loads on with a short 8' wide by 24-32 ft. high shear wall. Assuming the aspect ratio would even allow us to do that. Doing something like the third page I have shown helps that ratio significantly.
RE: Wood Shearwall with Openings
There is so much we do that isn't in the Code, but is good engineering judgement. Especially with those king studs acting as tension ties and the entire wall sheeted with WSP.
No problem with those hold downs for a church. I would definitely use the 3rd method.
RE: Wood Shearwall with Openings
Also, one small thing I noticed with your calls. Your shear force to the wall piers should be distributed baer on stiffness (ie wall deflections) not just total length. Since your lengths are reasonably closest probably won't make a huge difference though. Shearwall deflection and therefore stiffness is based on a combination of flexiral stiffness, shear stiffness, nail slip, etc. your method is only taking into account the shear stiffness and neglecting the other contributing factors.
RE: Wood Shearwall with Openings
RE: Wood Shearwall with Openings
RE: Wood Shearwall with Openings
The reason for this is that the third sketch area 1 will IMHO have four points of reactions, the ends and each side of the doorway. While I can justify the pier ratios per the third sketch, the calculating the reactions would take more time and effort than justified.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Wood Shearwall with Openings