huangyhg

old beam sizes
i have some old beams (from early 1900's)which i have the measurements but do not know the sizes. could anybody help me with this. beam#1 has the following measurements:
depth=14.75, bflange=5.5, tflange=3/8". beam #2 has the following depth:10", bflange=4", tflange=3/8". i need i and s values. also what is their strength?
check out our whitepaper library.
measure the web thickness and ill calculte it for u.
get the web thickness as boo1 has stated and calculate the moment of inertia; the formulas are in the aisc manual (both asd & lrfd). in ninth edition, asd see the following:
for a pair of flanges, page 6-19, equal rectangles, axis of moments through center of gravity.
for the web, page 6-17, rectangle, axis of moments through the center.
since the axis for both the pair of flanges and the web is the same, add the results of the above equations. you now have a good approximation of "i" for the beam.
divide "i" by "depth/2" (distance to the extreme fiber) and you have "s".
you can also accurately draw the cross section in autocad and then use the mass properties command to calculate the centroid and moment of inertia.
i did a quick look in aisc historic shape reference, and didnt find anything matching your dimensions for steel from 1887 to 1952. a b24x35 #/ft and a b35x36 #/ft may be close, but the tf is off. as for beam #2, i didnt see anything with 10" in depth and 4" in width. sorry.
pylko:
what is the tf for those two sizes? it maybe that the measurement is a little off. if the tf shown is 1/4" then it maybe right. for beam #2 i made a mistake the bf=4.5" and not 4". is there anything close in the reference book?
if the tf shown is a little smaller than the one measured then we will be on the safe side. what are the properties shown for those beams?
thanks a lot.
there are many s-shapes, from s15x55 down to s15x33 that have similar dimensions to your first beam, but all the tf's are of 0.513" or greater.
for a b24x35 #/ft-
tf = 0.490
bf = 5.5
d = 15
ix = 367.9 iy = 11.6
sx = 49 sy = 4.2
b35x36 #/ft-
tf = 0.588
bf = 5.5
d = 15
ix = 405.1 iy = 13.5
sx = 54 sy = 4.9
similarly, for your second beam, there are many s shapes, from s10x30 down to s10x22 that fit your dimensions, but the tf's are larger (although not as much of a difference in thicknesses as in beam #1). i'd check those sections in your steel manual for closest matching properties.
there is a beam designated cbl10 with d=10 and bf=4.02.
also, a bj10 with d=10 and bf=4 and tf=0.319.
perhaps a b37x22 #/ft?
b37x22 #/ft-
d = 10
bf = 4.67
tf = 0.462
ix = 113.9 iy = 6.4
sx = 22.8 sy = 2.7
i skimmed through some old ref. as well--cambria ca. 1914, bethlehem 1928, carnegie, 1920--and didn't find any exact matches. for the 10", carnegie b11 x25 #/ft., 5/16" web, 5/16" flange at toe, is closest. the 14 3/4" dim. is possibly an indication that the section is worn, possibly from rusting or use/damage. you should look at the integrity of the beams/columns if you are intending to reuse. in those days, max. allow. bending stress seemed to vary from a low of 12,500 psi to a high of about 19,400 psi, (carnegie is 16,000 psi in bending)through the early 1920's. each mfr. was a bit different. good luck.
thanks for all the replies
could they be metric ?
are the "s"hapes, i.e. sloped flanges, or wide flanges, i.e. no slope flanges?

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