Bridge site 2 and 3: Compression check

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Visitor (not verified)
Bridge site 2 and 3: Compression check

If you use analysis of "envelope of simple span and simple made continuous", you will end up compression check results wrong. I found this when I switch from envelope analysis to simple made continuous analysis. The compressive stress check failed when I select "simple made continuous analysis" procedure, but successful when I select "envelope" analysis.

Pickings
Please attach your input

Please attach your input file, along with a description (i.e., beam/span/location/limit state) and someone will look into this.

Richard Pickings, P.E.
BridgeSight Inc.

Rick Brice
I've tried to reproduce this

I've tried to reproduce this problem with several different bridge configurations. I have not been able to find a case when the compression stress check passes in "Envelope" mode and then fails in "Simple made Continuous" model.  Please provide an input file and the specific steps you are taking to create the issue.
 
Rick
Richard Brice, PE
Software Applications Engineer
WSDOT Bridge and Structures Office

jingjuan (not verified)
PG super compression check

Hi,

Attached is the PGsuper file I used. Please note that I use manual input of live load distribution factors due to the irregular layout. This might be the reason you couldn't reproduce the bug if you use standard layout.

jingjuan (not verified)
Another attachment

Here is another file. I found the same problem. This is 3 spans, 8 girders bridge, with skews. Check the compression for bridge site 2, fails if I choose "simple span made continuous" but successful when I choose "envelope".

Rick Brice
I've confirmed this to be a

I've confirmed this to be a bug in the software. The issue only comes up when there are larger than normal superimposed dead loads. For your case you have a sidewalk loading on the exterior girders.

For your case, it seems that the stresses can be resolved by increasing the concrete strength.

This issue will be fixed in version 2.5 which should be released as soon as we finish the final beta testing.

jingjuan (not verified)
Another file

It seems this bug still exists even if I take out the sidewalk. Please see this modified file. Still 3 spans, 8 girders, but no skews, no sidewalk. Check the compression on bridge site 2 for span 1, girder A, the results are fail when using "simple span made continuous, but green (>1.0) when using " envelope".

This bug wouldn't be found if you don't put too much prestress on the girders, since both of them will pass, but I guess the numbers will be different.

Rick Brice
It is a matter of the

It is a matter of the magnitude of the stresses at the ends of the girder compared to other locations. Knowing that the bug exists, the prudent thing to do is to look at both the simple span and the continuous span cases.

It looks like this is bridge in Hawaii. Can you provide us with some links to Hawaii standard girders and design practices? We would like to include Hawaii in the PGSuper.com community library. Thanks,

 

 

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