Do you have experience with bar joist design and install? Your joist look to be heavy duty, made with angle instead of bent bar. All joist like bridging top and bottom.
None at all! But I have a friend that has used them in his commercial work and I'm leaning on him. These bar joists are lighter and the angles are formed along with some of the webbing? being a small formed channel. To be safe, I'm only spreading them 4' apart. I'm all ears if you've got some suggestions or if you see me screwing up.
They are stronger than a bar joist because the cross section of steel is greater than a round rod typically used in the webbing. All bar joist have a metal tag wired to them before they are painted. That tag has the info needed and along with measurements you can take to find out load rating and required bridging. Start scrounging long pieces of rebar, rod, small angle. Anything you can weld to the the top and bottom chord to keep them from twisting. Use a bearing plate on top of your post and depending on strength of your post, you may need to reinforce it down to the height of the bottom chord. Bottom chord probably needs to be braced to wall at a 45 degree angle. Also, yours is an atypical installation with the joist perpendicular to the roof slope. This may require additional bracing. Joist are very strong for there weight, but only if braced properly. Are there any retired structural engineer FHC members that can help? I can help you with filling out this form. Joist Investigation Form – Steel Joist Institute
My tag. I did some checking previously at the SJI and get lost in the loading numbers. My sloppy handwriting is what's on the tag.
My plan is to *cross the joists from the eave to the peak @ 2' centers, then cross *again parallel with the joints on 2' centers. My "barn metal" roof needs this to walk on and is not comparable to the normal roof decking used commercially. I'm thinking that this will satisfy the bridging for the top chord and will just buy some more #6 bar for the bottom. Any idea on the spacing? The overall length to the bearing points is 37'4". Maybe divide the bottom chord into 4? * full dimension 2x4, rough sawn of course .
Canam is still in business. There's a way to reverse engineer your truss with the depth design tool. How deep is the joist? What are dimensions of bearing plate?
I understand what you're doing with the 2x4's at 2' on center each way. The 2x4 rafter bearing on the joist needs to stand up and the 2x4 crossing purlin can lay flat. The rafter's need an angle clip screwed (don't weld, use 2 heavy tek screws or drill and bolt) to the top chord of the joist and put these at the panel points of the joist. I can't see how many panel points there are in the pic, but if it's a little more than 2' spacing that's ok. I think an engineer would agree this would satisfy the top bridging stresses. Look at your the bottom chord of your joist for bolt holes or signs of 1-1/4" angle being welded to the top of the 2 bottom angles. That will give you original spacing of bottom bridging.
I'll have to search "angle clip", my thoughts were to saw a wood wedge that will be my transition to both the 3-12 pitch and to wood. I was advised to simply put a fender washer on my GRK lags and screw up in between the top angles of the joists. What I haven't decided is do I make this "wedge" continuous or just maybe 12"-16" shorts to center under each 2x4 (on edge). My roof framing lumber list is long enough already . I need to remember that the only alternative for a 37' span is wood trusses and I bought these 11 joists for $4-$500 . Any thoughts on my above wedge transition to wood? We're getting a nice rain, sorry about the holiday vacationers but we've been VERY dry with virtually no rain in May and really need it.
There's 4 #6 bars running around the entire length. I drilled and hydraulic cemented in support bars. Used 30 - 20 feet pieces and thought that I'd have 6-8 leftover
No need for wedge. "angel clip" a piece of angle with unequal legs cut to the width of the bar joist. Horizontal leg 1-1/2" long. Vertical leg 3-1/2 " high. Drill 2 holes in horiz leg and tek screw to joist. Drill 2 holes in vertical leg to bolt vertical 2x4. You want the clip and 2x4 on the panel points. Can't get a lag up thru at that location.
