These are notes from last year. This problem may have been fixed to be reasonable, i.e. able to be solved using the beam graphs.
This is one of the new problems, and we didn’t notice that the charts don’t go to 40 feet.
Segui gets a first guess by looking on page [3-119] to see what beams are stronger than needed, and sees a W24x146 and tries it first. Sadly, it doesn’t work, so he skips several and finally gets up to a W24x146 and it works.
I don’t mind that, but guessing at an initial beam and checking it using the long equations, then finding it wrong, and having to do it another 6 times is nonsense. OK, if they’re paying me by the hour, but not that much.
The answer was a W24x146. Start there, and just check it out using the equations.
Incidentally, when the charts for anything gives an answer outside the graphs, they are trying to get you to refer to note (c)
(c) Hey, jackass. Ever think of buying a brace? It will cost you about 10% of what it will cost to find a beam that will span 300 feet without being braced every now and then. It’s not like it’s at a column that restricts visibility, you know. The bracing goes above the ceiling tiles. Goodness.