american standard channels - aisc 9th

huangyhg

american standard channels - aisc 9th
i am preparing some miscellaneous steel shop drawing details.  i want to have a gusset connector plate shop welded to a c12x20.7.  aisc 9th gives the average flange thickness, grip and "k" dimension.  but what is the actual thickness at the extreme toe end/edge of the flange?
thank you ...
i don't know.  but the slope, i believe, is a 1 in 6 slope.  you can locate the average thickness at the midpoint, draw the sloped line through it, and be reasonably close.  i'm not sure if the average thickness is based on the flange area through the web, or to the line of the web, which would alter it a bit- and the average thickness could perhaps include some of the radius material.
thickness at base of flange = 0.723"
thickness at tip of flange = 0.280"
at least that is what they were in 1923, for a carnegie steel (us steel predecessor) c2 with 2.94" flange (current designation c12x20.7).
go to my website homepage (link below) and download "carnegie pocket companion - 1923". see the figure on page 27.
probably are minor variations from other manufacturers (and other time periods), but even today the above numbers should be reasonable.
tip thickness is misleading because there is a radius at the tip.  
deutero,
since you're a detailer, you probably can do this.  i did it with autocad.
1.  draw back of web (vert line)
2.  draw outside face of flange (hor line)
3.  offset flange face by distance k = 1.125" (this gives hor centerline of fillet.)
4.  offset back of web by 0.282" (this give inside face of web.)
5.  offset that by r = 0.50".  (this gives vert centerline of fillet.)
6.  draw line through intersection of both cl's at slope of 1:6.  (jstephen is correct about slope.)
7.  offset this line by r = 0.50".  (this give inside face of flange.
8.  put in a fillet of r = 0.50" to the inside face of web and inside face of flange.
9.  measure or dimension the distane from the intersection of fillet and inside flange face to outside face of flange, i measure 0.6318".  (slightly different from slideruleera's value from 1923 carnegie.)
10.  also, offset back of flange by g = 1.75"
11.  measure or dimension distance between outside face of flange and inside face of flange at this location, it is 0.4568".  that is closer to 7/16" than it is to 1/2", but maybe they round up for the grip.  
12.  offset back of web by 3" to find tip of flange.
13.  measure or dimension distance between both flange faces at this location.  i measure 0.2484".  (slightly different from slideruleera's value from 1923 carnegie.)
13.  ifrs is correct about the radius on the tip of flange, but i do not know that value.   
i think that gives you a good enough picture of a c12x20.7
regards,
chichuck
chichuck,
thank you for the information.  two questions:
what resource do you and jstephen have that tells you the inside flange face is a 1:6 slope?
what resource do you have that tells you the "g" value and what does it represent?  also, re: #10, did you mean to say "offset back of web" or am i misunderstanding?
thank again ...
chichuck,
is this "g" value available in a resourse for all channels or applicable shapes?
1:6 slope is standard for american standard beams (s-shapes) and american standard channels (c-shapes).  that's like asking for verification that the sky is blue!
look in the asd manual (green book) page 1-9.
nutte,
thank you for the reference.
i typically star people for informing me of something i did'nt know.  why did you have to add the insult?
no insult, just being funny.  this is up for debate.
deutero,
i found the g value, the distance from back of channel to normal gage line in an old (1978) bethlehem steel shapes book.  i think it used to be in the older aisc manuals (7th and 8th editions) but i dont have those handy to check.  i'm pretty sure the value i gave is still good, i don't think those have changed.  
also, i don't thinkd nutte was trying to be insulting, he's just ribbin you a bit.  though i was amused by it, you are asking about something that is somewhat obscure.  see astm a6 - 95c in section 3.1.2.7 for channels and section 3.1.2.5 for s shapes, there you find flange slope at 16 2/3% slope = 1:6.
regards,
chichuck