25' Beam Span analysis with OWSJ point loads

[imcivilized]

I know this is a no-brainer, but I'm having a bit of a brain freeze and don't have access to any books at the moment.
I've got a W12x27 beam, 25 foot span. There is a udl on the OWSJ putting a force of 12.45kips on the beam in three places, 6.25' apart.
I check the Ireq and the beam has lots of capacity to also put a 1kip lifting load (5kips with FS=5)

To also check the Mu for the beam, do I need to sum the moments caused by the three OWSJ loads, then the point load?
Is the length for PL/8 still 25 feet if the OWSJ provide support every 6.25'?
I don't do this every day, and am still just a lowly EIT...
have pity on me.

 

[JAE]

This sounds like basic analysis, simply putting together a simple span with a number of concentrated loads. Since you are an EIT, you should be working for a PE doing this kind of stuff....can you simply ask the PE?

 

[imcivilized]

Never mind.

 

[trainguy]

Wow. You're using a W12 beam for a 25 foot span? You should DEFINITELY get the input of a PE. I also don't see how PL/8 applies to your situation.

 

[whyun]

Are you neglecting the live load? Situation you describe appears to be a roof condition. Is it not?

Speaking of Mu, are you designing the beam in LRFD?

Consult your supervisor for direction if you are not sure. To get the moment diagram, apply point load individually and superimpose each of the moment diagrams (long way), or use the equations in the AISC ASD 9th edition beam equations (better way), or just use a computer program (easy way).

Good luck

 

[trainguy]

The moment can also be obtained by calculating your reactions, taking a section at the midspan, and summing the moments from all forces, udl's and reactions like we learned in the second week of Statics 101. For deflections, use your steel handbook's beam formulas for each load separately and sum the deflections at the beam's midspan. I suspect your span to depth ratio is too high, thereby giving you excessive deflections!