Beam chart Difference Between Black and Green Steel Books
Beam chart Difference Between Black and Green Steel Books
(OP)
Hi there,
Did ya'll noticed that the moments given by the black book's beam charts are generally larger than that by the green book's?
For instance on the black book, for W14X43 with 20ft unbraced length, the available moment is 109.5 kip-ft;
On the green book, the available moment is 81.5kip-ft.
Anyone gotta an explaination for this, please?
Did ya'll noticed that the moments given by the black book's beam charts are generally larger than that by the green book's?
For instance on the black book, for W14X43 with 20ft unbraced length, the available moment is 109.5 kip-ft;
On the green book, the available moment is 81.5kip-ft.
Anyone gotta an explaination for this, please?






RE: Beam chart Difference Between Black and Green Steel Books
green book is based on ASD, basically load combination without load factor except sometimes with a 0.75 factor in some combination.
RE: Beam chart Difference Between Black and Green Steel Books
I don't know why they're so different, without digging into the equations. The lateral torsional buckling equations changed between the two versions, but I wouldn't have expected the values to differ so drastically.
RE: Beam chart Difference Between Black and Green Steel Books
I feel for all the old-timers out there, who've fought as long as they could. (including my boss)
RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
If you plotted a curve of the design results versus LL/DL ratio for ASD and LRFD, there was a point where the two curves crossed.
It is my understanding that the new black book has the two curves basically in line with each other now. So choosing between ASD and LRFD is now more of a matter of convenience than economic advantage.
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
That's not the case. The equations are calibrated at a LL/DD ratio of about three. Lower than this, LRFD is more economical.
Think about this. The capacity is static. There is no way to tweak capacity based on LL/DL ratio.
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books
They are very sneaky.
RE: Beam chart Difference Between Black and Green Steel Books
AISC calls is stress design in the preface but then calls it strength deign in Chapter B.
Yes it is very sneaky.
RE: Beam chart Difference Between Black and Green Steel Books
RE: Beam chart Difference Between Black and Green Steel Books