example ch2-12

04-Unexpected behaviour/errors
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suchart.l
Posts: 1
Joined: 01 Nov 2012, 01:04

example ch2-12

Post by suchart.l »

Has anyone ever encountered this problem ?

I am trying to run the verification example ch2-12.

However, it said that "Zero diagonal terms encountered at the following nodes: node28(CM1) and node29(CM2)"

Maybe, I have some problems with my example input file.

Could anyone please send me the correct one to suchart.l@psu.ac.th

Regards

Suchart Limkatanyu
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ruipinho
Posts: 166
Joined: 07 Dec 2013, 14:37

Re: example ch2-12

Post by ruipinho »

Suchart, hi.

The warning message that you report (and which I also obtain when running this example) is, just that, a warning message, not an error message (and, in fact, the analysis still runs).

I suggest you carry out a search on this Forum (or on the Help/Manual of the program) on the expression "zero diagonal" in order to better understand the meaning of such warning message.

Best,

Rui

PS: it may still be the case that it was not the intention of Seismosoft's development team for this model to lead to such warning message, and they may even want to correct it in the future, but, I repeat, the point that I am trying to make is that the 'zero diagonal' warning message is not necessarily an error message (in fact, many of my own models lead to such messages, and they are not wrong, it is simply my structures that have particular features)
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seismosoft
Posts: 1271
Joined: 06 Jul 2007, 04:55

Re: example ch2-12

Post by seismosoft »

Dear suchart,

The warning message is output, whenever the program encounters an item of the diagonal of the stiffness matrix that is zero, which means that a certain degree-of-freedom is completely free without any support. Although this can be a potential source of instability and covergence difficulties (which is why the program outputs such message - to warn the users) this is not necessarily bad. For instance the rotational DOFs in trusses are indeed free.
In the particular model that you mentioned node28(CM1) and node29(CM2) are free in the z, rx & ry directions.

Seismosoft Support
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