COMPRESSION SIDE BRACING Steel Beam

[Materofact]

40 foot steel beam 2 supports at 28 feet,6 foot cantilevers, outer beam for a 6 foot deck/walkway support. Question: simple construction of wood joist to wood plate bolted to beam count for fully braced compression side? (also compression side switches on the cantilever).

Let the madness commence....

 

[HTURKAK]

Will you post some sketches showing the steel beams , joists, plank , hand railing ?..is this a footbridge?

 

[jayrod12]

For positive bending yes, negative bending no.

 

[BAretired]

Let the sketching commence.

BA

 

[Materofact]

 

[Materofact]

i drew a pretty pic and everything. but crickets.....

 

[phamENG]

You're in California, so I'm assuming you're designing to AISC 360? Have you checked the capacity of your wood framing to steel connection against Appendix 6, strength and stiffness of nodal beam bracing?

 

[JLSE]

No. Its top flange braced, not necessarily compression flange braced. I think a reasonable approach is to consider the unbraced length to be that length of the beam under negative moment.

 

[BAretired]

To be on the safe side, it would be prudent to provide bottom flange bracing at the inflection points.

BA

 

[milkshakelake]

6' cantilever means that you have a compression flange on the bottom due to negative moment, which means that it needs to be braced. Top flange bracing is not enough.

 

[KootK]

For me, it would go like this:

Detailing

- steel columns.

- Four bolts to cap plate and stiffener pairs over column such that the beam can plausibly be considered rotationally braced at the columns (effectively both top and bottom flange restraint at this locations.

- No discrete bracing unless that is somehow aesthetically tolerable.

Center Span

- Lb = distance between columns. No inflection point bracing.

- Cb = Whatever makes sense for the moment diagram.

Cantilever Span(s)

- Kc = 2.5 per the clip below.

- Cb = 1.0

 

[BAretired]

I agree with the KootK method. Brace the beam at each column using cap plate and stiffeners, then select a beam which can carry the load with an unbraced length of 28'. Makes sense.

BA