Seismosoft | Earthquake Engineering Solutions

Indeed, the infrmDB element follows the cubic formation. For details on its formulation refer to:
https://help.seismosoft.com/seismostruct/2026/en/element_classes/infrmdb.htm

The model assumes constant axial deformation and linear curvature distribution along the element length, which is exact ...

The basement nodes are restricted by the model components (e.g. rigid diaphragms of the slabs). If there are shear walls in your building, you need to model them.
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The elasto-plastic moment-curvature curve of the member in DBPH is created after section analysis and the bilinearization of the M-k curve. For more details, please study the details of the lumped plasticity model.
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These differences are related to small differences in the initial stiffness between the two types of elements, DBPH and FBPH. Whereas in FBPH the stiffness is updated at each step of the analysis, in DBPH the moment-curvature curve is bilinearized and initial stiffness is kept until yield. The ...

The cracked stiffness is only used in the linear methods. In pushover analysis both types of elements, DBPH and FBPH, start with the uncracked stiffness and gradually, with increasing deformations, their stiffness decreases.
The differences in the stiffness degradation is related to how inelasticity ...

Can it be that the specified pga in the spectrum for seismic demand is zero?
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Yes, once the code-based check is reached all the response parameters of the member (stiffness, shear, bending moment) drops to the specified percentage, e.g. 25%
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Indeed, this can be done. What I meant was that it is not possible to start a new analysis retaining the stress-strain condition of the members from a previous analysis
In the valid approach that you mentioned, what users are usually doing is to input a very large record with several recordings one ...

Yes this probably means uplift of the footing, after which the program is unable to find numerical convergence. There is no automatic way to prevent this in SeismoStruct. You need to check out the details of the footing and the analysis (probably with the help of your supervisor).
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As we wrote in the previous post, the shear capacity, this depends on several factors, including the axial load, the ductility, the Lv ratio and compression zone depth. You need to check all these values, in order to estimate the correct shear capacity. However, the shear capacity is expected to ...