Modifying stiffness of reinforced concrete columns and beams for EC8 dynamic earthquake analysis

SOFiSTiK
1

Is it possible to reduce the bending/shear stiffness of columns and wall elements without affecting their vertical stiffness in Sofistik/Teddy. If so how should I go about doing it?

I am wanting to reduce the by 50% to account for concrete cracking in my elastic analysis in accordance with Eurocode 8.

I am aware that I could simply reduce my E-Modul by 50% to achieve this but this would also reduce the vertical stiffness. Unfortunately we are also interested in the vertical response of the structure so reducing the vertical stiffness is not an option.

Another option is to use the command SVAL to modify the properties that I am interested in (e.g. Iy, Iz) however the manual says that this will remove the geometry from the section and that it can be used only for static analyses.

Is there an option that retains the geometry/can be used for dynamic time history analyses?

Thanks in advance for any help you can provide.

2

with our new workflow RSA reloaded this is easy possible inside an SSD task.

Please see our tutorials depending on the modelling platform Revit or SOFiPLUS
https://www.sofistik.de/documentation/2024/en/tutorials/building/building-seismic-bim/building-seismic-bim.html
and
Reinforced Concrete Building - Seismic Analysis (SOFiPLUS Workflow) - SOFiSTiK Tutorials 2024’
This should answer your questions
Have a nice day

3

Look at comand GRP2 in module ASE.
Maybe it would help.

4

Thanks for the reply Martin. That is a nice and easy way to do it for RSA. How would I go about doing it if I wanted to conduct a linear time-history analysis?

5

With:
GRP N FACS 0.5
GRP2 N STEA 2.0
you reduce all stiffnesses by half and then grp2 multiplies axial stiffness by 2, so it is a basic value.