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Bracing a Wide-Flange to Bar Joists

Bracing a Wide-Flange to Bar Joists

Bracing a Wide-Flange to Bar Joists

(OP)
Please refer to the attached sketch.

I have designed two columns and a 36'-0" wide flange beam to support a movable partition. The top of the beam will be 14" below the bottom of the bar joists. The calculated deflection of the bar joists at the beam location is 1-1/2". I would like to brace the beam, both perpendicularly and parallel to, to the bottom chords of the bar joists. Any loads in the bracing would then ultimately be transferred into the roof diaphragm. I do not want any significant vertical roof load transferred to the beam.
Can you suggest a method to accomplish this?

What member makes the best sense to use as the braces, angles, tubes, or heavy gauge metal studs?

Thanks

EIT

RE: Bracing a Wide-Flange to Bar Joists

Is this better?



RE: Bracing a Wide-Flange to Bar Joists

Other considerations:

1. I did not consider bracing the beam parallel to the joists. You could field weld some plate between the joist bottom chord angles, each end of the L6x4 angle, leaving acceptable gap between PL and angle. This assumes the typical 30K joist will have angles for a bottom chord.
2. How much load do you anticipate transferring into the roof and are you comfortable with it?
3. You may want to alter the W10 to W16 connection if that does not seem stiff enough for you.
4. You may want to field weld the L6x4 in place at time of erection.
5. As you stated, you could probably use back to back 10" cold-form CEE's in lieu of the W10x12. However, the difference in weight versus handling (2) pieces instead of (1) may not be worth the effort.

RE: Bracing a Wide-Flange to Bar Joists

You could design to beam to span unbraced and just brace the ends where the joist deflection is closer to zero.

RE: Bracing a Wide-Flange to Bar Joists

Here's another option. I'd recommend just bracing the end posts and designing the beam to not require LTB bracing. If you must have the LTB, you can weld posts to the top of the beam at intervals and brace the tops of those posts in the same way. Maybe throw in some partial height stiffeners at each post if there's room.

And like BVSD's solution, you'd need lateral braving for the joist bottom chords. Forgot that in my sketch.



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.

RE: Bracing a Wide-Flange to Bar Joists

You will want to let the Architect know that the adjacent ceiling to partition soffit will need to allow 1 1/2" vertical movement (+/-), which will be kinda funny.

If you use long horizontal threaded rods, you can allow for a lot of vertical differential while still holding the beam laterally. You could even put the rods right into the beams web and save a plate and weld.

RE: Bracing a Wide-Flange to Bar Joists

Teguci's idea will definitely save on material cost!

RE: Bracing a Wide-Flange to Bar Joists

(OP)
BSVBD,
Thank you so much for that suggestion. I did not think about getting the angles on the W10x12 in between the angles of the bottom chords (yes they're angles and yes the joists will have cross-bracing). I will just have to quickly check that the downward deflection of the support beam added to the upward deflection of the joists from wind uplift, does not exceed the 2" where they could become misaligned. This is probably highly unlikely, but I'm new and frankly tend to over-think things. I do not anticipate much lateral load (I will design for 400 lbs). I agree to field weld the L's at erection. I will see how much kick-back I get with the W10x12. Also, thanks for posting again so I could see your attachment.

Wallache,
True. I don't see why I couldn't.

Kootk,
Thank you for your time.

Teguci,
The architect and the owner are aware of the large deflections. Thanks for the thoughts though.

EIT

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