Eigenvalue analysis of masonry infilled frame

[Subedi Naresh]

Dear SeismoSoft team,

I have modeled a three story reinforced concrete building with masonry infill using the infill element available in the SeismoStruct. When I run eigenvalue analysis, how does the program define the stiffness matrix of the infilled frame ? (By this I mean how does the program know which strut is in compression and which one is in tension for the activation or deactivation of shear springs ? Does that mean the stiffness of all the struts is taken resulting in very smaller value of time period of the building due to very high stiffness ?).

Thank you.

Regards,
Subedi Naresh

[seismosoft]

Hello Subedi,
Indeed, since the program cannot know which strut is in compression and tension, the stiffness of all struts is considered in eigenvalue analysis.
Note however that the the inf_strut response curve features also a tensile branch, which has the same initial stiffness as the compressive branch.
Seismosoft Support