Concentrated load applied to top flange of W-shape

[CTW]

I'm considering ways to eliminate the resulting torsion from a 3 kip horizontal concentrated load applied to the top flange of a W-shape and would like some opinions.

The space between the flanges on one side of the beam have to remain clear of obstructions and a wide flange has to be used. I'm also limited in size so I can't use a stout wide flange and just design for torsion.

What I'm considering is using a full depth stiffener on one side of the beam at the location of the concentrated load to transfer the load to the bottom flange, and then provide a strut on the bottom of the beam to transfer the load to another member.

Feedback on this detail is appreciated as well as alternate solutions.

 

[Lion06]

What is the "other member"? If you can provide a strut to "another member", why not use a HSS post with a depth to match bf/2 + 2" (or so). Use a cap plate and the stiffener you talked about and weld the WF to the cap plate at the edge of the flange and near the web. This will take the torsion directly into the HSS post.

 

[msquared48]

Can you add a beam transverse to the beam with the torsion, at the point of intersection of the column, that frames to another beam to take out the torsion?

The connection of the two beams would have to be a moment connection, but this is the simplest way I can think of in doing it.

Mike McCann
MMC Engineering

 

[CTW]

StructuralEIT-
Unfortunately the post can't be added.

msquared48-
I can't add a transverse beam.

 

[Lion06]

What kind of strut were you talking about?

 

[Lion06]

Can you weld a side plate on the WF (on the side you were going to add the stiffener)? It would be parallel to the web, and be welded to the top and bottom flanges to create tube section.

 

[jike]

Can you create a horizontal truss to transfer the lateral load?

 

[kslee1000]

Anybody seeing any problem with his original concept? It sounds a way to go if the member supporting the strut is stiff enough. A quick sketch should gain better understanding.

 

[msquared48]

OK, then I agree with SEIT - create a tube section.

Mike McCann
MMC Engineering

 

[Lion06]

What is the WF supporting? If there is a floor (or roof for that matter), why not add a drag strut at the location of the horizontal point load and take it into the diaphragm?

 

[msquared48]

Or... what structural member is transferring the 3K lateral force to the top flange of the beam?

Can this force be both tension and compression?

Mike McCann
MMC Engineering

 

[BAretired]

"What I'm considering is using a full depth stiffener on one side of the beam at the location of the concentrated load to transfer the load to the bottom flange, and then provide a strut on the bottom of the beam to transfer the load to another member."

This concept works if:
* the strut and other member can sustain 3 kips force horizontally.
* the strut is connected to the stiffener to resist a moment of 3k*depth of WF.

Without the moment connection, the concept does not work.

BA

 

[apsix]

As he said; "Without the moment connection, the concept does not work."

 

[csd72]

Are you still there CTW?

Can you post a sketch?

 

[kslee1000]

ctw: see attached for some suggestion.

 

[JStructsteel]

I like option #2

 

[CTW]

I'm still here. I had a busy day yesterday (and still today) and didn't have time to post until now. I see there's a lot of questions and suggestions so hopefully the attached sketch can shed some light on the subject.

The force is only applied in one direction.

No members have been designed yet as I'm only trying to look at load paths at this point, but the beam is required to be a WF.

I considered plating one side of the beam to form a tube as StructuralEIT suggested, but then started to brainstorm alternate ways to do this.

My thinking with the torsion is that since it's located at one point along the top flange, then the force could be transferred to a strut on the bottom flange.

Keep in mind when viewing the sketch that no member can be located in between the flanges on the left side of the beam or the top of the beam.

 

[CTW]

The previous sketch was turned 90 degrees and there may be some viewers that can't rotate it so try this sketch.

 

[BAretired]

CTW,
The member on the bottom cannot be just a strut, which implies axial compression only. It also has to develop the moment P*d where d = the depth of the WF. If it can do that and if the other member to which it is attached is stiff enough, your detail should be adequate.

An angle stiffener with the outstanding leg away from the web would be stiffer than a plate. Looks like the 'strut' should be deeper.

BA

 

[Lion06]

Can you get a WT in there or something else with a little more meat? As BA says, it has to take the moment, Pd, and the axial force. I would also want to make it pretty stiff to keep the top flange from trying to roll simply because of the lack of flexural stiffness of the "strut".