We are working on a new project with Rudd Construction. It is a large heavy timber storage / barn structure. What makes this interesting is we have a clear span of 50′ with some shed dormers on top. This creates a fairly large tension load on the bottom chord among other things. We have a connection that we can use to resolve this. In fact I have blogged about before. Click here to see the article. The connection itself looks like this:
We are working with an engineer that we have never worked with before. His name is Dodson Harper and he is with Resource Engineering Group out of Crested Butte CO. After speaking with Dodson about the 43 kip tension load he recommended a stave bolt connection. It is something I had seen and heard about but had never used. We did have to change the location of the bottom chord but this is a great way to resolve these loads in a very efficient way. We have spec’d out this connection with Dodson’s help and I am excited to use it in this project.
Let me know if you have seen or used any interesting connections using any type of material. It would be great to hear about them.
Hi Eric-
Is there a reason you don’t want the tie to run over the post and under the rafter? That’s a common solution to this condition, esp. in Europe. Birdsmouthing the rafter into the tie, with a simple bolted connection though the top of the rater and to the bottom of the tie, can take up tremendous thrust.
Otherwise, this connection reminds me of a Timberlinx.
Chris,
We have used the birds-mouth with lag screws in the past. To be honest we didn’t run the numbers but I assumed that we couldn’t get enough capacity for the 43 kip tension load using a birds-mouth. I call that “design by inspection”, kind of like Johnny Carson’s Carnac. It seems that there are a few limitations using that connection when you have higher tension loads. You could have relish failure behind the birds-mouth or by the time you make the birds-mouth deep enough you have removed a lot of “meat” from the bottom chord. We are also fighting some height restrictions and raising the tie bought us a couple of extra inches.
Now that you mention it I think I will take a closer look at your idea. I could be making assumptions that aren’t true. It does have a lot of similarities to a Timberlinx.
Any suggestions you might have would be greatly appreciated.
By the way, I am not an engineer. I am just a guy who loves building wooden structures!
Thanks for your input.
I like that cool steel birdsmouth connector…
I know. That connection is awesome, I wish I could remember who came up with that!
Looks like a very elegant solution… Where is this one being built?
Dan,
Thanks, it is another Aspen project.
Eric,
This is indeed a clean (invisible) way to resolve the tension loads in the bottom chord. Tension can be resolved directly in line with the member centerlines and not introduce any additional moments in the connection. It does, however, not leave much room for the transfer of other loads to the column. Uplift and lateral loads, although probably much smaller than 43K still need to be considered in this connection.
Hein Brutsaert
Hein,
You are correct. We do have other bracing and connections not shown for clarity in order to resolve these lower load conditions. Hope all is well with you and congrats on Brutsaert Structural Engineering.
Eric Seelig