Back-to-Back Channel Attached to OWSJ Bottom CHord

[Eng_Struct]

Hi Group,

I need to specify connection between back-to-back channels to the bottom chord of the joist. The channels are there to support pipe hangers. The total load at each end of the channel will be 1500 lb.

I am envisioning a connection similar to the one below. Instead of full length rod, I will use rods that go through the space between joist bottom chord and will have a washer bearing on top of angle vertical leg.

Will I need to pretension the bolt to get clamp force? Also, any concerns with anti-loosening of the nuts under constant tension load? Any other watch its?

I believe I will have to specify the spacer between the channels but I am not sure how the middle spacer will be welded to the along its full length - I do not want the channels to spread open.

Thanks in advance!

 

[KootK]

Will I need to pretension the bolt to get clamp force?

I would avoid that for fear that you would locally buckle the joist flange angle legs.

Also, any concerns with anti-loosening of the nuts under constant tension load?

Not for me unless you see a vibratory component to the loading.

I believe I will have to specify the spacer between the channels but I am not sure how the middle spacer will be welded to the along its full length - I do not want the channels to spread open.

1) You could make the spacers a little shallower than the channels so that you can finagle an accessible fillet wild in there.

2) Instead of spacers between the webs, you could at patch plates to the flanges.

3) You could through bolt the spacers instead of welding them.

. The total load at each end of the channel will be 1500 lb.

You've probably already go this but 1,500 lbs is not insignificant for a joist chord which you'll be loading off panel point. To that end, if there is cause for concern, perhaps try to exert control over how close to the panel points the attachment will be.

 

[jerseyshore]

You've probably already go this but 1,500 lbs is not insignificant for a joist chord which you'll be loading off panel point. To that end, if there is cause for concern, perhaps try to exert control over how close to the panel points the attachment will be.

A load like this on a bottom chord gotta be at the panel point. Otherwise, add a strut to make it a panel point. No way I would load two dinky bottom chord angles with 1500 lbs.

 

[Eng_Struct]

Thanks KookK & Jerseyshore!

I will be specifying the hanger within 6" of the panel points to avoid bending in the bottom chord.