what is the rating of an i beam

huangyhg

what is the rating of an i beam
help,
   i have two i beams that are not rated as to their max. load. they are used for overhead hoists. there sizes are: 27 inches by 10 inches by 57 feet and the other one is 20 inches by 6 inches by 19 feet. presenly there isn't any rating of max. load on these i beams.
you have not provided sufficient information to determine what you need.  i suggest a load test to determine the rating for cranes, not computations.
i agree with ron that you need to conduct a load test, but you do need additional information before going to that step. to start with - what are the ratings of the hoists?
then - beam flange thickness, web thickness, steel grade (if available), approximate age of the beams (nominal sizes have changed from time to time over the years). depending on your findings, there may be other issues to look at (end connections, etc.)
after making some calculations, you can get an idea of the load needed for test purposes.
sturms,
i agree with ron and slideruleera, you have not provided enough information.  those beams are pretty hefty and one is a long span to just assume capacity.  
i the past i've determined the capacity mathematically, checking span, bracing and beam condition and then load test.  mathematically gets me in the ball park, load testing (which is required in most us states) qualifies the crane system.
jjf
are these beams solely for the crane?  or are they structural supports for a building or other structure?  what supports the beams themselves?  what kind of end connections do they have?  are there lateral supports on the beams?  
your question could be very simple or very complicated depending on a lot of information that is not shown- you'l problaby want a professional engineer to examine the situation, rather than just getting a load for a beam.
if the beams weren't designed for the cranes, then it could well be that the allowable load is "zero".
you shouldn't necessarily need to rate the beams at any higher capacity than the cranes that they support- which could simplify matters.
thanks ron, slide rule era, jjf, and j stephen for your great advise.
                             sturms