Cross Beam analysis

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YL0101
Cross Beam analysis
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Binary Data Bridge model194.49 KB

I'm working on a concrete bridge load rating. The bridge is a 2-span prescast prestressed concrete girder bridge. There are 5 girders spaced at 6ft on center, and the cross beam is 28ft at Pier 2 supported by 2 columns, and the bridge is symmetrical.

The load rating report for cross beam at pier 2 seems wired to me. The negative moments due to DC load is not symmetrical, the max. negative moments at one column is about 800k-ft, but at the another column is about 1100k-ft. But when I checked the analysis graphic for the cross beam, both moment and shear due to DC load are symmetrical about the centerline.

So I'm wondering why the graphic and the report show different results for the same element? And also I checked the girder bearing/reactions at cross beam, it looks good.

Attached is my model for your information.

Thank you
Yuan

Rick Brice
Cross Beam analysis

Please post your file so we can investigate what is going on.

YL0101
I've updated my post with my

I've updated my post with my bridge model attached. Could you take a look. Thank you.

Rick Brice
Cross Beam analysis

I posted a reply last week. Not sure what happened to it. At any rate, the numerical results in the report are symmetrical except at the CL Column as expected. The columns and cross beam are integral so there is a "jump" in moment at the CL Column. The magnitude of the jump is the top of column moment. You can see this in the graphical results.

What you are seeing in the tabular results is the moment on the left side of the CL Column.

We will improve the reporting of cross beam moments at these locations.

YL0101
Thank you Rick! Sorry I didn

Thank you Rick! Sorry I didn't see the post last week. So which number should I use for cross beam load rating? Is the moment/rating factor at around 5' location is more reasonable?

Thank you!

Rick Brice
Use the larger value for

Use the larger value for positive moment and the smaller value for negative moment ratings.

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