Ways to Increase Wood Beam Bearing Area

[T_Bat]

Hey Everyone,

I have a few heavily loaded multiply LSL beams that are bearing on a double 2x pine top plate. My triple ply beam woorks for everything except sill plate bearing (or I guess crushing really). Instead of adding more plies is it possible to nail blocks on each side of the beam at bearing to increase the bearing area? You would end up to something similar to squash blocks beside and plywood web joist. Seems reasonable to me but I'm not sure if I'm missing something. There is porbably some nail slip/deformation that will allow some movement but is this something anyone else has done?

Thanks!

 

[BAretired]

You could use a steel bearing plate sized to meet permissible bearing stress.

BA

 

[msquared48]

Yup.

Mike McCann, PE, SE (WA)

 

[T_Bat]

I've always heard of that solution for this situation. I assume you just rout the bottom of the beam so it's ends up flush with the floor? I'm still wondering if the "stiffeners" I propose are a viable solution.

 

[EngineeringEric]

You can use Simpson Truss Bearing Enhancers if you are close. Same concept as blocks so i'd buy your option

 

[XR250]

Ironically, i have seen many LVL's crush more than the supporting pine plates. This has been in crawlspaces exclusively so it may have to do with excessive humidity affecting the LVL's more than the pine.

 

[T_Bat]

Thanks for the input guys. I guess I'm just trying to figure out what would bea easiest from a constructability standpoint. It's probably 6 of one a half dozen of the other. I may note my drawings with an option for both.

 

[charliealphabravo]

I can't see a problem with fastening blocks to either side of the LSL to increase the bearing area, as long as the connection is sufficiently stiff to share the shear load. Nails and screws may work but I have used shear plates and split rings if I really need to make sure something shares load.

Dapping the beam and adding a steel plate seems unnecessarily complicated and even counter-productive since the steel will need to be thick/stiff enough to spread the load.

That Simpson connector also seems a bit counter-productive since it adds nails to the member zone that is failing.

 

[XR250]

You could put a PSL post under that spot that runs thru the plates and splice the plates back together with straps.

 

[T_Bat]

I'm not that overstressed ≈15% so I think I may look at the blocks first. If this were a wood structure I think the PSL is also a reasonable alternative. However this is actually a hybrid steel/wood building. Metal stud walls with wood floor framing. It's been a learning experience and frankly next time I think I'll push for all wood next time. I appreciate all the responses guys (and/or gals).

 

[KootK]

I guess I'm just trying to figure out what would bea easiest from a constructability standpoint.

I'm pretty sure that most contractors would prefer your detail. I worry about the fastener slip too but mostly let it ride. Plate bearing stress is a deformation limit and, in my experience, it's pretty common for practitioners not to lose much sleep over it. You might attach the blocks with Simpson SDS screws and install them pointing downwards 30 degrees. I'd think that would tend to help the slip issue.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[T_Bat]

pointing downwards 30 degrees

If I nail/screw from the blocking to the beam wouldn't it be better to install them upward pointing? Seem the upward angle would better "leak" load out to my blocks.

Although I think after typing that out I see the downward angle would tend to pull the screw down and that would be resisted better by the srew head on the block.

Or maybe not - haha. I think I'm just confusing myself now.

 

[XR250]

I would mot lose sleep over 15%. I think the NDS somewhere allows a 100% overstress on this limit state

 

[msquared48]

You could always go to an LVL plate too.

If this is a multi-story building,limiting vertical settlement or crushing of plates is important cosmetically.

The plate crushing will stop when the necessary bearing stress is attained.

Mike McCann, PE, SE (WA)

 

[T_Bat]

It's a two story structure. The other thing in my favor is that I'm designing for a 100 psf live load. The occupancy is a yoga studio though so likely will never be fully loaded. Although who knows what this thing could be in the future.

I guess I may need to look at moisture control if it's hot yoga...

Thanks for the help everyone.

 

[BAretired]

If I nail/screw from the blocking to the beam wouldn't it be better to install them upward pointing? Seem the upward angle would better "leak" load out to my blocks.

No! The blocking is bearing down on the plate which means the plate is pushing the blocking up. To hold it down, you should install screws downward pointing.

BA

 

[T_Bat]

You’re totally right. Like I said - confused myself thinking through it. I like it guys - blocks it is.

Msquared48 - how common are LVL plates? Is there a story threshold you would consider them for?

 

[jayrod12]

LVL plates are becoming more common as we keep going higher. Generally we've gotten standard plates to work for 3 storeys and lightly loaded 4 storey walls. Haven't had a chance to do 5 or 6 storeys but I imagine you'd need something stronger.

 

[Scratch3r]

I was at a seminar where some new wood fastener techniques were being explained.

Its possible to reinforce wood with screws when loaded perpendicular to the grain.

Link to My-ti-con Paper

 

[Tommy385]

Something like this?

https://www.fischer.de/-/media/fixi...hash=23C47D4CE2E31BCB44E5DB3053D8F5CD95035D83

But im not sure if something like that is allowed outside Europe,
note: a steel bearing plate is still necessary.