Old beam...fMn values
Old beam...fMn values
(OP)
I have an old beam (1900 or so) and I have to determine the uniform distributed load it can handle. I found an AISC document on slideruleeras page that gives the dimensions of the beam but I am looking for the φMn values. Does anyone know where I can find these values or do I have to calculate them by hand? Thanks.






RE: Old beam...fMn values
RE: Old beam...fMn values
BA
RE: Old beam...fMn values
RE: Old beam...fMn values
Determine your moment from M=wl^2/8 and then use the LRFD manual to find a beam with a Phi b Mr values that exceeds the moment. Then you check for deflection with 5wl^4/384EI.
RE: Old beam...fMn values
RE: Old beam...fMn values
www.PeirceEngineering.com
RE: Old beam...fMn values
Don't disregard what BA brought up.. Cast Iron is much more brittle, and AISC would NOT apply.
RE: Old beam...fMn values
BAretired's suggestion to determine if the beam is iron or steel is a good one, either is possible and it will affect your answer. A minor correction of a detail... 19th century beams were made from WROUGHT iron, not cast iron. Cast iron was used for compression members, like columns, but even 120+ years ago metallurgists knew that cast iron was way to brittle for the tensile stress in beams. Manufacture of wrought iron beams was phased out by the mid-1890's; the largest size ever made (to the best of my knowledge) was 20". Anything larger had to be steel.
RE: Old beam...fMn values
Design Guide 15 has a lot of information on older steels.
The method you are using to design the beam only makes sense if it is actually a uniformly loaded beam.
RE: Old beam...fMn values
RE: Old beam...fMn values
BA
RE: Old beam...fMn values