GSD Hinge vs. Midas Hinge
I need someone to walk me through how the hinge created in GSD is recreated in Midas Civil when exported.
Axial Load:
For my case, hinge yield surface properties in Midas Civil show a Pmax of 9,785 kips and the component properties show an axial force of 15,000 kips. That 15,000 kips is there because I could not get GSD to export a hinge for axial loads in the normal range, only for very large axial loads (is this normal? acceptable?). Throughout the pushover analysis, a given column sees no more than 2,000 kips.
Are the hinge properties being recalculated at each pushover step using the correct axial load or is the hinge always using a very large axial load, thereby showing an exaggerated capacity?
Idealized Yield Curvature:
What yield curvature is being used as the governing limit in Midas? Is the idealized yield curvature being used to set the point at which first yield occurs in the FEMA hinge? What is being used as the ultimate limit? Rebar or Concrete Curvature? Each are given in the GSD Moment-Curvature analysis.
I have attached my GSD and Midas Pushover files.
What I am still missing is how the idealized yield gets imported from GSD.
Midas shows this:
That 3642 kip-ft is not the idealized yield strength at P = 1757. Rather it is the moment when P = 0 kips as shown on the interaction curve. So, for the given Axial Force shown, when M/MY = 1 @ Point B, is this suggesting that My = 3642? I think probably not, but I can’t see where the idealized yield moment and curvature generated in GSD are being employed in Midas.
Thanks for getting back. As you said, the moment being displayed there is for 0 axial force. The yield moment is taken up based on the axial force from the PM curvature as exported from midas GSD. Kindly refer to the image below.
Now, about the interaction curve values, these are taken up from GSD as shown below.
I hope this clarifies the doubt about the moment interaction in GSD & midas Civil. If clarification is required in some other aspects, kindly let me know.
Regards,
Nandeep
Technical Manager, MIDAS
Nandeep,
Yes, this seems to be taking yield moment for design (P-M) rather than yield moment from moment-curvature.
Hope this helps. Kindly let me know if you have any further questions on this.
Regards,
Nandeep
Technical Manager, MIDAS
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4x6 Section.mgs 7 KB |
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Vineyard Pushover.mcb 2 MB |
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GSD_export to plastic hinge_Process.xlsx 580 KB |
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Use of Midas Products at Caltrans_Answer_5-12-17.docx 671 KB |
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PMM Plasticity for Nonlinear Analysis of Beam-Column _ 2017.10.docx 730 KB |
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MIDAS-inelastichinge-questions-rev2.docx 1 MB |
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