OWSJ from 1940s or 1950s 1

Those are Anthes Allspan joists.

I tried to upload the catalogues but am for some reason getting runtime errors from the attachment process.

I will note, these things have notoriously unreliable joist seats. There were a lot of failures of these due to excessive joist seat extensions that weren't reinforced properly.

Let me know if you're able to get it from my personal google drive link Anthes catalogue

Here's the joist catalogue supplement. It let me upload that.

- Yeah, if you think there's any chance of ID'ing the manufacturer and getting capacities, do that. You're in Canada but SJI in the US offers an online submission service where they'll trying and help with this exercise if they can.

- These are some weird looking trusses with the goofy angle of the webs and there being no verticals shorten the top chord panel spacing (something that you could fix potentially). It doesn't look to pro to me. As such, I'm not optimistic about your chances of ID'ing the joists and finding published capacities.

- I'd start with an upper bound look at flexural capacity assuming that you could develop the squash load of both chords and see where that gets you. If that number looks promising, you'd then have to start thinking about the multitude of other possible failure modes that would yield lower overall capacities. Local member buckling, failure under beam/column load conditions, web capacity, weld capacity, seat capacity...

From an evaluation perspective, I detest working with the joists made from cold formed hat sections. I've found these to be pretty difficult assignments.

I don't suppose that you have access to the original load rating for the floor? If you do, you can ratio the new demands on the trusses relative to the, assumed, original capacities and cross your fingers that the difference is small.

jayrod12 said:

Here's the joist catalogue supplement. It let me upload that.

Click to expand...

Kudos. This will have to make its way into SRE's replacement website at some point.

KootK said:

Kudos. This will have to make its way into SRE's replacement website at some point.

Click to expand...

I'm not certain, but that might have been where I got it in the first place. haha. That old website was the source of many of my reference materials.

The thing that always drives me nuts about this style of joist is the lack of weld between the web members the chord members.
You have a limited length available for this weld based on the radius of the bend in the web members, and I`ve never been able to get the welds to check out.
Good luck!

jayrod12 said:

Here's the joist catalogue supplement. It let me upload that.

Click to expand...

Thanks jayrod12. You solved a few questions that I have been trying to figure out for a couple of weeks. I will have to scavenge the building and check if there are any joist extensions but I don't think there are any.

I will look into this literature and get back to you guys if any more questions!

Cheers!

There are 2 locations with these OWSJ. The one that I have most information is not the short span that you see in the picture. I have identified it as a B184 - it is 18" deep and I identified the bottom chord to be a No.3, I still have to check the top chord to ensure it is a No.4. The joist spans 29'6" so I will use the 30' span on the loading table which yields a "total safe load" to be 144psf.

The manual doesn't seem to specify how to use the chard in terms of ASD v. LRFD. Should I assume they have already provided a factor of safety on these loads? The manual mentions a "correction factor" on the deflection formula but that's about it. Maybe I should use the formula to ensure I get a L/360?

Another concern of mine is that this manual is from 1963 while I know the building was built in the 40s/50s.

Anthes had been around for a while. I don't have anything older in my electronic files.

We recently moved offices and our paper library hasn't been unpacked yet.

Those tables will be ASD.

thanks again jayrod12.

For the short joists, I identify them as B82 joists and they span 15'. The supplement only takes you as far as 12' (image below). It doesn't look very promising eh?



I am wondering if the way to go is to add more supports in between since these are spaced at 24" o.c. Though I don't have the original loading, it would double the capacity of these joists, and I just have to check the beams, columns, footings.

Were you able to download the full catalogue from the link? There may be more span ratings and info in there than in the supplement.

I've had joist suppliers provide new steel joists with a mid-span splice so they can erect it inside an existing building. So that may play well with your last proposal, i.e. adding in additional supports to cut the load on the joists in half.

Gents, just an update:

I measured members and performed a structural analysis on both OWSJ types. It turns out that these joists are very different from the ones on the catalogue. As I understand from the catalogue, web members are "rings" that range from 1-1/4" to 2-1/2" diameter. See below. These joists on site are bars ranging from 12.7mm to 14.2mm diameter. Based on my analysis, the existing webs are very weak in compression as the KL/r with these webs is very low.




Could it be that these joists are composite?? If so, how would I go about finding out if they are and its strength?