How node coordinates are defined?

[caps0013]

I was wondering how OpenSees defines the coordinates of a node after an analysis. This is important because the model that I am running runs through one analysis, then additional nodes and elements are added, then another analysis is run. I have been getting a warning for zero-length elements for that are defined after the first analysis (between a previously existing node (1) and a new node (2)) that says the element is longer than the tolerance for a zero-length element. This occurs even though the new node, node 2, is defined as the original coordinate of node 1 + [nodeDisp 1 1]. However, when I define node 2 only as the original coordinates of node 1 (without the node displacement of 1 from the first analysis) I do not get the warning. Does this mean that the warning for zero-length elements is only dependent upon the coordinates when the node was initially defined, or is it dependent upon the location of the nodes when the element is defined?

Also, I have tried using the nodeCoord command to output the coordinates of element 1 to determine its location at the end of the first analysis, but it appears to always output only the initial coordinates, not the displaced coordinates. Is this another case where this command is only based off the initial definition of the element and not the location of the displaced elements?

[fmk]

most elements when added after the model has undergone previous deformation will add the current displacements to nodal coordinates in determining their length, etc. ..
subsequent nodal displacements have these initial displacements subtracted in determining element state.