Location of min/max camber

[Lion06]

I have to apologize for this question, but where do you find the minimum and maximum cambers for steel shapes? I have been looking through the 13th edition steel manual, but can't find it. I found it once before, but didn't tab it.

 

[COEngineeer]

EIT, I dont know where it is on the manual but I have an intersting article from Modern Steel Construction July 2006 by Erika Winters Downey. She wrote a list when NOT to camber a member:
1. when the required camber is less than 3/4"
2. Length of beam less than 24'
3. web thicness less than or equal to 1/4
4. Spanderl beams
5. Beams in moment frames
6. Beams shallower than 14"
7. Beams subject to significant twist
8. Beams with cantilevers
9. Beams with braces framing into them
10. Beams with a non uniform cross section
11. Beams with significant non symmetric loading.

I usually do 4" max camber as my default on my software. good luck.

Never, but never question engineer's judgement

 

[Lion06]

I have that article, too. It is good, but I have some long beams (around 70') that would only need to be cambered around 1" to 1.25" and I think that may be less than the minimum for a 70' W36

 

[WillisV]

See Table 1-10 (p1-186) of the Second Edition LRFD manual (silver one). Table was subsequently removed from 3rd. ed. manual - did not think it was placed in the 13th but I could be mistaken.

 

[lkjh345]

FWIW:

Looking back over several office building jobs over the last several years, I have often shown 1" to 1.5" camber for 60' to 70' W30's. The local fabricators don't seem to have a problem with this, as I have never had a question on it.

 

[csd72]

If you need a camber for a 70' beam then I would be very careful about the vibration.

 

[Lion06]

I've already checked vibrations. I am under L/240 for total deflection, but on a 70' span that's still pretty high, so I'm just trying to cut down on the magnitude of deflection.

 

[slickdeals]

Have you tried using composite joists or is depth a limitation?

 

[fasboater]

I am not sure if this is exactly what you’re looking for but you can check out section 16.3-27 in the code of standard practice AISC thirteenth edition (6.4 fabrication tolerances).

JB

 

[Dinosaur]

ASTM A6 gives a lot of information about the quality requirements for steel plate and rolled shapes, including permissable camber. You may be able to learn something from that spec. Good luck.