You guys are correct. The strut forces in the purlins used to be neglected in design. I heard that from an old timer when I started 20 years ago. Hasn't been that way since I started. You don't necessarily need purlin bracing if you have a through fastened roof because the AISI has formulas...
The comment I was responding to was the one above yours which is about the loading in the direction perpendicular to the rigid frames, in particular if the above fix would suck some load from the bracing system which has nothing to do with the lateral system of the rigid frames. Any experienced...
I want to add something about the flexibility of PEMB structures--They're much more rigid than you think in the direction perpendicular to the rigid frames due to an abundance of redundancy. Hypothetically, wind load travels from the top of wind columns through strut purlins until it hits the...
Very nicely done. I'm a PEMB guy. The 8" pipe columns are schedule 40 std 8" pipe. Round HSS is not readily available on the market despite being listed in the steel manual. also the pipe column was definitely designed as pinned-pinned.
I jacked out a column supporting (2) 5 ton cranes on...
I'm a PEMB guy and I would run. One thing you want to look for with PEMB suppliers is that they are IAS certified. It's the same as being AISC certified for a conventional fabricator. They come in a few times a year and audit your engineering, business practices, and most importantly, shop...
The difference in load based on control type is due to speed. Pendant cranes go as slow as a man can walk. Cranes controlled from a control room (radio) go faster and therefore create a larger dynamic load. Cab cranes go even faster and therefore have even higher loads.
These days most...
I'm a PEMB guy. One thing I've seen a lot of foundation engineers get wrong is the direction of the shear wind loads on rigid frames. When you have vertical loads like dead or live, it pushes down on the rafter and the columns want to kick out. The opposite happens in wind loads due to high...
I'm in a hurry but I believe the ACI code gives the required spacing but makes exceptions for products with tested values with closer spacing. If you free download Simpson Strong Tie anchor designer, I know it will allow about 4db for many of the epoxy anchors, depending on diameter. I presume...
You might find help in crane beam design resources. They are usually some type of built up section due to the need for strength in both directions. Crane-Supporting Steel Structures by R.A. MacCrimmon is a great resource with design examples. You can get it free. Just google Canadian crane...
These things can bend a lot in their weak axis without yielding. If you can get it straightened out and nothing has yield line, then it's remained elastic.
https://youtu.be/V7zOZbCQ94M?si=qPRy6IQNFzt9Jw8p
I'm guessing a PEMB erector would be a good resource for how to get the rafters back to...
These type of canopies are added to PEMB type buildings all the time without requiring any complex analysis. Lots of companies sell canopies like this "off the shelf" that are just installed anywhere on a PEMB building. Presumably, the off the shelf canopies are aluminum and very light. May...
I just want to discourage anyone from using photos from a storm and pointing at one example of a building failing close to others and making conclusions about entire building systems. I attended a research symposium a few years back where a professor studied building failures after Hurricane...
If I'm reading your post right, you've performed tests where you pulled on a fastener until it pulled out and you got 530 lbs.
For one, you check pullout using ultimate strength, not yield strength.
For two, it depends on the diameter of the screw.
That being said, assuming a 1/4 (#14) tek...
The odds of you getting it to work are low. I'm a PEMB guy and buildings we designed a few years ago wouldn't be shown to work for the newer wind loads. Not only has the wind loads gotten stronger according to the code, the wind maps are totally different. Because the IEBC required anything...
240 kips?
I'm a PEMB guy and that sounds crazy. I checked a 200 ft clear span hangar that we did recently and the largest lateral factored load is 74 kips ASD.
So if you haven't already, either question that loading or figure out how it's so large. The biggest lateral loads on PEMBs are due...
FM not only charges somewhere near $10k to do a test to get one assembly rated, you also have to pay $10k per year to keep your product listed. Any tiny difference means they get to charge for a different assembly in perpetuity. FM is not your friend when it comes to using common sense or...
