Uplift on interior beam/joist

[JStructsteel]

Checking shop drawings for some floor beams and I joists in a residential home, the designer has some spans with multiple bearings, and thus producing uplift at some bearing locations.

What (if anything) have you folks done for this in the past? Do you try and restrain that end of the beam with a hold down of some type?

Thanks

 

[milkshakelake]

How is there uplift without wind loads? Is it due to live loading on a single span that produces a cantilever effect? I've never come across that; I'd think that a fraction of the dead load of the stud wall at the ends is enough to keep it down. But if there is uplift, I think the nails between the joist and rim joist would be sufficient. If not, I'd add an angle or lag screw to the rim joist and call it a day, without doing straps or hold downs. It's unlikely that an entire rim joist would be in uplift due to the joists.

 

[Tomfh]

How much uplift?

Does it still work if you ignore the final support?

 

[JStructsteel]

Its from a short span then a long span support for the same beam. deflection upwards is very small, so not a huge issue the more I loook a it. Values vary 500-700 lbs.

 

[phamENG]

I usually look at these as if the reaction isn't there and see what deflections are. As long as the downward deflection remains in spec and the upward deflection is 1/8" or less, I let it go. More than that, and you could reasonably expect cracking.

 

[Aesur]

I typically add in H clips at each bearing point, however when I have conditions such as you describe, I tend to detail it to use separate staggered joists to avoid these "uplifts". They don't always do that, and I have been known to let it go as a single joist if the loads aren't crazy and the H clips work, however there have been times I have made them field cut the joists to create separate joists. What annoys me more is how they tend to try to use "non-load bearing" walls as supports.

 

[XR250]

You can also request that the beam be designed as two single spans. I has a 2-span once where two of the bearings were 24" apart. The lumber supplier's software showed something like a 5k uplift there.