C/D Ratio Not Matching Capacity and Limit Values

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ajplankis
C/D Ratio Not Matching Capacity and Limit Values

I am working on a prestressed girder design and in the Spec Check output, it is showing that the compression at Interval 12 is failing with a 0.98 ratio, even though the demand of -3.337 ksi is below the compression limit of -3.825. Can you help me figure out why this is showing up as a failure? I've attached an image of the spec check output I'm referring to.

Thanks.

Rick Brice
Hmmm... that does look

Hmmm... that does look suspicious.
Please post your PGS file.

ajplankis
PGS File Uploaded

Hi Rick, I just uploaded the PGS file to the original post.

Thanks!

Alivia Plankis, PE

Rick Brice
C/D Ratio Not Matching Capacity and Limit Values

The C/D ratio for compression is actually correct. The Service I and Demand stresses listed for compression are from the simple span analysis when in fact the continuous span analysis produces the governing case for compression. The correct value is used in the CD ratio, but the wrong value is used in the reporting.

This problem is caused be the optional "Tensile Stress (Service I)(Effective Prestress + Permanent Loads = Final Stress without Live Load)" setting on the Prestressed Elements tab in the Project Criteria.

This is an optional criteria and isn't used often. If you don't actually need it, disable the check. Otherwise, enable the check to evaluate tension correctly and then disable the check to evaluate compression correctly.

We will get this issue resolved for the next release.

ajplankis
Thank You

Thank you so much for the quick response. I do need to include that optional criteria for our current client, but I think I can get away with just using Simple Spans Made Continuous, instead of the envelope of both simple span and simple made continuous. This also seems to resolve the issue.

Thanks again.

Alivia Plankis, PE

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