Please make sure that you are connecting the end nodes of the infills with the RC frame i.e. the nodes should also be connected to RC members. This is how the infill element works.
Seismosoft Support
Hi!
Can you kindly tell me how to get rid of the "zero diagonal terms" error message in the top node of a cantilever column? My analysis is being terminated because of this.
The message means that some of the DOFs in your model have zero stiffness. Make sure that you have all your nodes connected and that the members are correctly connected and restrained.
Seismosoft Support