Eliminating nailer on steel beam under wood framing 2

[B. Evans]

Client wants the shallowest possible beam. New beam will support the existing joists above - so it will be a dropped beam (not a flush beam). Back in 2018 a member (Scratch3r) posted "I recently used a 45-degree washer to screw the top flange of a steel beam to the underside of an existing top plate. It saved me adding a nailer to the top of the beam. The client appreciated the extra headroom."

Does anyone have details or photos that I can show a contractor? New steel beam will likely be a W6 so the wedge washer seems like it would work because otherwise there would not be enough room for screw gun to make a 90 degree up connection.

If you dont have a photo or detail with the wedge washers do you have another detail/photo which eliminates the top nailer, such as side cleats? Thanks.

 

[alt0]

Why not make it a flush beam with hangers?

 

[AaronMcD]

Why not make it a flush beam with hangers?

Not OP but I assume they don't want to shore and cut out all the existing joists.

--------
Maybe OP can drill up through the top flange at each joist to screw in from the bottom. Or add nailers to the sides.

Out of curiosity, what happens if the joists are not fastened at all? Just push 'em up a bit with the beam, add blocking, and let them just sit there.

http://www.hellodwell.design

 

[Eng16080]

Every time I've had a client this concerned about head height, we ended up with a flush beam and joist hangers, as alt0 wrote. In any case, I understand that's not what you're asking.

Off the top of my head, I can think of the following possible solutions:
[ol 1]
[li]Get exact measurements of the location of each joist relative to the new beam. Drill 5/16" holes through the beam top flange at these locations (excluding the web and web fillet location). Then, use a right angle drill to install 1/4" wood screws (or whatever's needed) up through the top flange into the center bottom of each joist. This is perhaps not great considering the coordination needed for this to succeed.[/li]
[li]Same idea as above, but the holes are drilled in the field. Less coordination, but drilling the holes might be a pain.[/li]
[li]Install flat wood blocking above the beam and between the joists with the blocking well connected to the joists. Then, similar to option 1. provide holes in the beam top flange, except, now there is no need for the holes to be perfectly aligned considering that there's a full wood surface above the beam for attachment.[/li]
[li]Maybe it's possible to clamp something to the beam top flange which attaches to each joist. I recall once seeing something like this, although can't recall the specifics.[/li]
[li]You could pack out the space between the beam flanges with wood and then connect each joist to the wood using a Simpson H2.5 or similar connection.[/li]
[li]This idea just seems wrong, but I'll mention it anyway: if it's not necessary to restrain the beam against buckling and there aren't any other lateral or uplift forces needing to be transferred to the beam, just leave the beam disconnected. My disclaimer is that I've never done this and would need to check the code first to see if this is prohibited.[/li]
[/ol]

Whatever you end up with, it would be wise to add vertical wood blocking between the existing joists centered above the beam.

EDIT: AaronMcD beat me to it on a few of these.

 

[DoubleStud]

How about adding blocking between joists and just glue the steel beam to the blocking and the joists? Maybe just really screw it to the floor above at the support? You can always run the top flange longer a little bit so you can screw it to the top. Are you really trying transfer load laterally on this beam?

 

[milkshakelake]

Great ideas here. Another idea is to use PAFs (powder actuated fasteners), like Hilti X-U. Connect something like an L3x3x16GA to each joist with PAFs to steel and Tek screws into the joist. Then run bocking between the joists, nailed to each joist.

I really don't like the idea of not fastening to the beam at all. I've seen wood joists pulling away from walls and connecting members so many times, even with real connections. I believe it's absolutely necessary to connect stuff somehow or other.

The 45 degrees washer sounds like a hack job. That's how I install solar panels to construction fences for getting power to vibration monitors at job sites. Wouldn't trust it for a floor joist, which vibrates all the time. The screw is cantilevered and could twist just from normal vibrations sending lateral forces into the connection. The washer could go into inelastic flexure, making the joist loose.

 

[B. Evans]

The main purpose of fastening the steel beam up into the wood framing is to provide lateral torsional bracing for the steel beam. I would rather not design the steel beam as unbraced because it will increase the weight of the beam.

 

[XR250]

I am repeating some ideas already stated...

Flat blocking on top of beam between joists (fastened with Wood to metal screws or 1/4" Ø bolts or PAF's). I used this detail on my house.
Can also make the beam and drill a hole at each joist and then use a right angle driver for some short lags.
You could be adventurous and just glue it to the joists with POLY subfloor adhesive.

 

[DoubleStud]

Let's say you just put the beam below with 0 attachment (no glue, no nail, no screw), do you all think it is unbraced? I feel like the friction alone will brace it on the top flange.

 

[driftLimiter]

I feel like the friction alone will brace it on the top flange.

Ehh this seems precarious to me. AISC SCM has requirements for brace strength and stiffness that one could check but friction is already a tough quantity to determine, let alone rely upon for stability of the beam flange. If you had some birdsmouth or notches that envelope the flange then perhaps you would get what you need to resist lateral displacement of the flange.

The main purpose of fastening the steel beam up into the wood framing is to provide lateral torsional bracing for the steel beam. I would rather not design the steel beam as unbraced because it will increase the weight of the beam.

Maybe for a floor beam, but for a roof system you may have uplift loading to resist?

Some clips or tabs on the top of the beam would get you a positive connection and could be designed for all directions of required loading. Clips could be placed on the joists to the top flange, or maybe just the blocking to the top flange then have some connection from the blocking to the joists.