Older steel beam
Older steel beam
(OP)
While looking through a 1930 vintage building (two story), I came across a steel beam section with differing flange thicknesses. As best as I can tell with tape measure, the beam is 8" deep with 5-1/2" wide flanges. However, the top flange is 1/4" thick while the bottom flange is 7/16" thick. Bottom flange appeared to be slightly tapered similar to S-beam shapes.
Have never come across beam with differing flange thicknesses. Can anyone direct me to info on this beam type?
Have never come across beam with differing flange thicknesses. Can anyone direct me to info on this beam type?






RE: Older steel beam
RE: Older steel beam
Do you need to do any analyis on this beam or is the question simply for interest?
On the subject of logic - I can't see any point in having differing flanges unless there is something else (for instance a concrete slab) which provides greater stability to the thinner flange.
1930's engineers would have a good knowledge of structures so it may be that they have good reason for the beam being the way it is.
RE: Older steel beam
RE: Older steel beam
Yes you are right. Cast iron was weaker in tension than compression so the tension flange could be bigger.
Here in the UK cast iron was effectively obsolete by 1900. By 1930 we would definitely expect steel but we are a much smaller and more uniformly developed country. In the US I could imagine that cast iron would still be used in some circumstances much later.
If this beam is cast iron its load capacity will be significantly different to that of a similar steel component.
In my experience, you will not be able to tell by simply looking at the beam. Material testing is needed.
RE: Older steel beam