Beam Load Rating

[chastst]

This will be very easy for you structural guys, but it has been a while since I have worked with anything but pumps and compressors.

I have a 14W30 beam (building rafter), approximately 16 feet in length that is sloped at 18.4° (4 on 12). I need to determine that the beam can be used as a support for personal fall protection (tie-off). Policy states that it must support 5,400 lb per person. I would like to assume 4 people tied to the beam, and also worst case of all of them being at the same point (middle of span being worst case?). Could someone help me with the calculations that are needed to prove this?

Thanks
chastst

 

[COEngineeer]

For deflection L/480, W14x30 is good, you dont want to go any smaller though.

 

[IceNine]

What is the tibutary width for the roof load that this W14x30 is supporting? And what kind of roof load is it being subjected to?

 

[UcfSE]

You can use the AISC Manual to determine strength. That will depend mostly on the unbraced length of your beam and the yield strength of the beam.

You should have someone experienced with this do this for you, such as a supervisor, or hire a licensed professional to check it.

 

[tdsull]

PL/4 for moment.
PL^3/48EI for deflection
You may want to include an impact factor

 

[RockEngineer]

The 5400 lb/person is the factored load. I don't know many 5400 lb people around. When you do your PL/4 for the moment you length can be the horizontal projection instead of the full length so you get the load and perpendicular distance. That saves you a little since the horizontal projection is about 95% of the beam length on a 4/12 slope.

 

[IceNine]

If this is a roof rafter, say spaced at 8 feet on center carrying a ballasted roof, chances are it may be highly stressed already.

In addition to the PL/4 moment due the point load, you need to include the wl^2/8 moment due to the uniform roof load.

 

[boo1]

where does the loading come from?