steel truss bear on masonry

[DNBEA]

Does anyone do a sliding end for roof steel truss bearing on masonry wall? Just curious.

 

[msquared48]

If you are at a designated seismic joint between two buildings, etc., yes.

In the same building - most likely not as the wall, in all likelihood, needs to be laterally supported by the structural diaphragm that is supported by the steel joists.

Mike McCann
McCann Engineering

 

[AggieYank]

Not typically for standard steel roof joists on load-bearing CMU walls. If I decided there was a large thrust, or movement associated with relieving the thrust, then I'd consider it. Chances are though that if there was a very large steel truss with a lot of end movement involved, that it wouldn't be sitting on CMU anyway.

 

[Scoper]

I once saw cracking at the corners of a large masonry building that the A/E attributed to thermal expansion of the (fairly long) hip trusses, and inability of corners to move. Their solution was to epoxy grout the cracking and provide slide bearings for all the hip truss bearings. That was many years ago, and have heard of no problems since.

 

[DNBEA]

thank you guys. I have truss span 27ft bearing on CMU and the whole building is insulated. Do we need to have a sliding bearing? if we do what does it look like. I need to attach the truss to the bearing plates for uplift. so how can we do it?

 

[jike]

I have never done slide bearings where the CMU mostlikely needs lateral support at the roof due to wind or seismic loads. You don't want to cause the wall to have a lack of stability.

We have, however, done slide bearings where the CMU wall is supported by perhaps another structure and need expansion in your joist bearing for one reason or another. Provide a teflon pad bearing assembly for expansion and bent plate clips for uplift.

 

[DNBEA]

thank you. I am just curious. I dont think i need one either.