Joist hangers and end moments

[jay156]

When you're designing a floor that has wood joists framing into other joists, do you consider the hangers transmitting moment? I have three 2x10 joists framing into a double 2x10 and it's failing in torsion when I consider the ends of the single joists as fixed, but it's obviously okay when I call it pinned.

How would you model this? Is moment really transferred?

Maybe I should just upgrade to a larger LVL beam to be sure?

 

[SEARUN]

Typical hangers (face mounted/top flange) are a pinned connection. They do not have the capacity to transfer moment. Typical wood joist construction should be modeled as pinned.

 

[tony1851]

Joist hangers for timber floors are not intended to transmit moment.

 

[CANPRO]

Picture a cantilevered floor joist supported by nothing but a typical hanger at one end. You could tear it down with one hand....its pinned.

 

[jay156]

Thanks. That's what I thought.

 

[msquared48]

Depending on the connection to the purlin, a saddle hanger arrangement could transmit some moment across the beam, but I would not count on it. Just keep it simple...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[focuseng]

Vote: pinned.

BUT you could use tie straps to get the beam to have top and bottom bracing at each joist to prevent LTB rotation. Stability bracing is not too hard to come by.

______________
MAP

 

[RFreund]

I will also add (just to be picky) that depending on sizes/loading/span if you are only loading one side of a member then you may want to consider the effects of the applied torsion due to the eccentric load if the top of the 'one-side-loaded' member is not braced. Also you need to transfer the load to each ply.

EIT

http://www.HowToEngineer.com

 

[XR250]

How are you checking torsion in the double 2x10 anyway? If the joists actually transferred moment, the torsion in the beam would be self limiting as the joists would end up bracing the beam in torsion once they got done deflecting.

 

[hokie66]

Excel is correct. This situation is only compatibility torsion, not equilibrium torsion. This is usually ignored in wood framing.