Hinge properties - DBPH approach

[leartt]

Hello,
in the process of modelling a one-bay RC frame, by using the DBPH nonlinear modelling approach, there is an error message that states: the automatic calculation of the hinge properties is not supported for the selected section type. The section types are regular squared and rectangular RC sections, with defined longitudinal and transversal reinforcement. What could be the source of this error?
Kind regards

[seismosoft]

How do you get this message?
The automatic calculation of the hinge properties for the rectangular and square RC sections types is supported by the program, and we checked this feature and it seems to be working without problems.
Seismosoft Support

[leartt]

After I define the material models for concrete (Mander et al. nonlinear c.m.) and for reinforcing steel (Menegotto-Pinto), the RC sections of the bare frame elements and the Beam-Column element types with the help of displacement-based plastic hinge approach, I double click for example the beam of the frame in the infrmDBPH tab, and the aforementioned message appears. I am trying to conduct a static time-history analysis and because of this, the analysis is not fully conducted (unable to apply the next load step message is shown in the Processor tab).

[seismosoft]

Indeed, this is a bug of the GUI that will be fixed in the upcoming Release-3 of v2024 of the program. The message is wrongly displayed, however this does not prevent the users from changing the infrmDBPH element class and assigning the automatic calculation of the section properties.
Thanks for the help,
Seismosoft Support

[leartt]

Thank you for the information. So to sum it up, because of this bug, the analysis is not fully conducted using the DBPH nonlinear modelling approach? I was wondering this, since I conducted static time-history analysis of the same one-bay RC frame, with the same dynamic lateral load, and with all the four nonlinear modelling approaches (infrmFB, infrm FBPH, infrm DB and infrm DBPH) presented in SeismoStruct, and only in the case of DBPH, the analysis is not fully conducted (unable to apply the next load step message is shown in the Processor tab). This message is shown in the very early stages of the analysis.

[seismosoft]

No, the bug is only in the pre-processor; it is just the message itself that should not pop up. Nothing related to the analysis.
What you are experiencing is something else: the inherent numerical instability of the infrmDBPH model. Distributed plasticity models are much more stable numerically the concentrated plasticity models, something that we have experienced in SeismoStruct, but that also occurs in other similar FE programs.
Seismosoft Support

[leartt]

Thank you for the reply. Any tips on how to overcome these issues in this model?
Kind regards

[seismosoft]

You can refer to all the posts in this forum regarding convergence issues. Another way is to change the parameters for the Element Iterative Strategy (Program Settings). However, note that the model is generally less stable with respect to the force-based, distributed plasticity models.
Seismosoft Support