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AASHO-IV Girder - Bridge Crane Runway
5

AASHO-IV Girder - Bridge Crane Runway

AASHO-IV Girder - Bridge Crane Runway

(OP)
I am trying to analyze a prestressed girder dated about 1960. The company wants to upgrade the bridge crane from 50 tons to 85 tons.

Does anyone have any information on the prestress used then?  How about load tables?  I have a copy of a 1971 PCI handbook. The concrete tests showed about 5000 psi.

RE: AASHO-IV Girder - Bridge Crane Runway

An old AASHTO spec probably wouldn't give you any information on the particular girder you are looking at as girders come in all shapes, sizes, levels of reinforcement, levels of prestressing, etc.

Without the original design documents pertaining to that girder, you will have to verify its strength in some other way such as a load test.

 

RE: AASHO-IV Girder - Bridge Crane Runway

3
Another option to consider: - Design the (assumed) new 85 ton crane such that it imparts the same loads onto the runway system as the exisitng 50 ton. ie; more end truck wheels spaced farther apart, restirct hoist approach to runway beams (assists with veritcal load only). We have successfully put a 30 ton crane on a runway designed for 10 tons by doing this. Additionally. You will find that a new 85 ton hoist will weight the same or less than and "older" 50 ton. Hoist wieght contributes to lateral load into runawy beam.  

RE: AASHO-IV Girder - Bridge Crane Runway

Now that's good lateral thinking by FLCraneBuilder.  Just goes to show, when you need a good answer, ask the right person.

RE: AASHO-IV Girder - Bridge Crane Runway

or simply come to Eng-tips!

RE: AASHO-IV Girder - Bridge Crane Runway

I have done some bridge ratings and often found it possible to get behind the ends of the beams and count the strands and determind the strand pattern.    

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