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Stringer/Floor Beam Size

Stringer/Floor Beam Size

Stringer/Floor Beam Size

Hello everyone,

I have been working on the load rating of Bridge that was constructed on 1959. It has the stringer and floor beam specified as 24WF and 30WF: nothing else. How can I get the actual size of these beams and their properties?
P.S. I went through the AISC database. It has 24WF followed by other specifications and footnote which are neither given in the bridge plan nor do I know.


RE: Stringer/Floor Beam Size

AISC Design Guide 15 is probably your best friend here.

Historical WF shapes are designated by nominal depth & flange width in the historical AISC database, and you then have a few options on web / flange thickness. If you can access the beams at the abutments, you can measure the flange width & thickness which should be enough to identify exactly which shape you have (measuring web thickness in the field is a bit trickier/annoying). You can also look for a "CB" number - WF24 would be CB241, CB242, CB243, which you can match with Carnegie / US Steel handbooks: https://www.aisc.org/publications/historic-shape-r...

Otherwise, do the drawings indicate the flange width anywhere? Can you deduct approximately from other details? For a WF24, you can have 9", 12" or 14" flange width. Connection details may be enough to rule out at least the 9" flange width, so you could then use the smallest WF24x12 section in that case. Otherwise you're probably stuck with the smallest WF24 section in the database to be safe.

Hard to tell with your info but it sounds like you probably want to do a site visit. A 60 year old bridge can be in a very wide range of conditions - from essentially pristine and well-maintained to being able to poke your finger through the rusted-out web or flanges. In that case the original size is the least of your concerns smile

RE: Stringer/Floor Beam Size

If there is no other recourse, you let the owner know and ask if a field visit is possible to go and measure the dimensions of the beam.

You can use the AASHTO MBE to estimate material properties based on the year of construction.

RE: Stringer/Floor Beam Size

I agree with the other 2 comments that a site visit to measure the dimensions of the members, and to assess the condition of all the components, is necessary for a proper load rating of the bridge. Someone needs to do a thorough inspection of the bridge; if you can't, you'll need a qualified bridge inspector to look at all the critical components and report back to you, so that you can assess the strength of the components in their current condition. The AASHTO MBE will be an indispensable resource in the evaluation.

Rod Smith, P.E., The artist formerly known as HotRod10

RE: Stringer/Floor Beam Size

Mike said it best. If you can't find any information you'll have to measure everything. Been there, done that, pain in the @$$.

RE: Stringer/Floor Beam Size

Thank you so much everyone for your suggestions and advice. I have joined this forum recently and I already enjoyed being here surrounded by lot of intelligent people. Thanks!

RE: Stringer/Floor Beam Size

We're always glad to have new members. tiphat

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