old steel section properties 2

[jrfroe]

Does anyone have information on old/obsolete steel sections? More specifically, I need section properties for beams from around 1930, called out similar to either "24C-76#" or "24CB @ 76#". These sections are not channels as the "C" might suggest. They look similar to wide flange sections.

Thanks,
Jason

 

[JAE]

AISC Steel Design Guide 15 has a couple of shapes called CB241 and CB242 - both 24" WF sections with 76 plf weight. The 241 has a flange width of 8.985" and the 242 has a flange width of 9.75". Do you know what your bf is?

I'd suggest you go buy it - very good publication. Go here

 

[jrfroe]

I'm not sure what the bf is since all the beams are embedded in concrete. They were used in a bridge used to carry both vehicle and street trolley traffic and all the girders are embedded in a solid 3 to 4 foot thick concrete deck.

 

[PowerRanger]

I have a similar problem, but I have found out my beam's properties by calling BlueScope (AU). In your case, the beam looks act as the tension reo. But in my case, my beam is embedded in concrete 2 inches to all side. The beam is around by wires every 400mm ( for me, act looks like shear stud). The original design was in 1968, and I checked back the Austrlia standard, composite structure was publish in 1980. So I am not sure if I can assume it is composite structure. 2 inches concrete help me much, because before I checked the stell beam only, and it is just meet its current, and the architect want to attach a 150mm concrete deck on it.
Your comment will be helpful.

 

[dbuzz]

I have a copy of Ketchum's Structural Engineers Handbook (1924). In its tables the wide flange shapes, or H columns, only go up to 14" deep. There is a 'Carnegie I Beam' with a depth 24" and unit mass 74.2#/'.

Section properties are:
Depth(in), 24
Weight per foot (lb), 74.2
Area (in²), 21.70
Flange width (in), 9.000
Thickness of web (in), 0.476
I₁ (in⁴), 1950.1
r₁ (in), 9.48
S₁ (in³), 162.5
I₂ (in⁴), 61.2
r₂ (in), 1.68
S₂ (in³), 13.6

 

[JAE]

Powerranger - in past years (at least in the US) the 2" concrete encasement was intended for fire protection and not considered as a composite beam. In fact, I've found many cases where the encasement was still placed around the beam, but loose in that the flex in the beam had already broken the bond between concrete and steel. And there were some cracks and such - but held together by some minimal wire reinforcing.

So I wouldn't count on it being composite.

 

[jrfroe]

Thanks for all of your help. I just ordered the AISC design manual. I'm guessing the CB series that JAE has referenced is the one I'm looking for (what's the chance that two different series would use the same two letters?). And once I have the manual I can check to see if the other beam sizes called out match up with the design manual. As far as having two sizes for the same weight, I'll just have to use the most conservative.

Thanks,
Jason

 

[broekie]

Based on a year of 1930, my guess is that you have the CB242. The CB241 doesn't look like it was fabricated until the late 40's, early 50's.

I'm basing this on the AISC guide mentioned above. Definitely an excellent purchase.

 

[chichuck]

jrfroe,

I have an AISC manual dated 1946, it includes the following: WF shapes 24X9
W = 76 lb/ft, A = 22.37 in^2, d = 23.91 in, bf = 8.985 in,
tf = 0.682 in, tw = 0.440 in,
X-X axis I = 2096.4 in^4, S = 175.4 in^3, r = 9.68 in
Y-Y axis I = 76.5 in^3, S = 17.0 in^3, r = 1.85 in
detailing dim
d = 23 7/8 in bf = 9 in tf = 11/16 in
tw = 7/16 in tw/2 = 1/4 in
a = 4 1/4 in T = 21 3/8 in k = 1 1/4 in m = 25 5/8 in g1 = 2 1/2 in c = 5 /16 in g = 5 1/2 in

this is a little newer than you say your structure is, but the beam depth and weight match.

I also have a Carnegie Steel Pocket Companion (1923), it lists the exact beam that dbuzz mentioned.

maybe this will help.


Regards,

chichuck

 

[jrfroe]

I was able to get my hands on a 1946 steel manual, which has the same WF24x9, but most of the other shapes don't match up. Here is a complete list of shapes that are used:

6CB-60

8CB-48
8CB-60

10CB-36
10CB-100

12CB-32
12CB-83

14CB-68
14CB-245
14CB-255

18CB-52
18CB-78
18CB-100

21CB-58
21CB-64
21CB-70
21CB-86
21CB-98
21CB-104
21CB-112

24CB-70
24CB-76
24CB-85
24CB-94
24CB-100
24CB-110
24CB-120
24CB-140

27CB-85
27CB-101
27CB-112
27CB-124
27CB-137
27CB-145
27CB-160
27CB-175
27CB-190

30CB-115
30CB-126
30CB-138
30CB-151
30CB-180
30CB-200
30CB-240

33CB-125
33CB-138
33CB-152
33CB-200

36CB-147
36CB-175
36CB-230
36CB-275
36CB-300

Would someone be able to tell me if these weights match up to the CB series in the AISC steel design guide #15 or any other series for that matter?