3.1.9.1. ZeroLength Element

This command is used to construct a zeroLength element object, which is defined by two nodes at the same location. A zeroLength element is similar to a set of springs placed between two nodes, each spring providing the force displacement relationship for a specified degree-of-freedom. The nodes are connected by multiple UniaxialMaterial objects, which provide the force-deformation relationship for the element in that degree-of-freedom direction.

element zeroLength $eleTag $iNode $jNode -mat $matTag -dir $dir <-doRayleigh $rFlag> <-orient $x $yp>

Argument	Type	Description
$eleTag	integer	unique element object tag
$endNodes	list integer	2 end nodes
$matTags	list integer	list of n material tags
$dirIDs	list integer	list of n degree-of-freedom directions 1,2,3 - translation along local x,y,z axes, 4,5,6 - rotation about local x,y,z axes
$x	list float	(optional) 3 components in global coordinates defining local x-axis
$yp	list float	(optional) 3 components in global coordinates defining vector yp which lies in the local x-y plane for the element.
$rFlag	integer	optional, default = 0 rFlag = 0 NO RAYLEIGH DAMPING (default) rFlag = 1 include rayleigh damping

Note

If the optional orientation vectors are not specified, the local element axes coincide with the global axes. Otherwise the local z-axis is defined by the cross product between the vectors x and yp vectors specified on the command line.

The valid queries to a zero-length element when creating an ElementRecorder object are ‘force,’ ‘deformation,’ and ‘material $i matArg1 matArg2 …’ Where $i is an integer indicating which of the materials whose data is to be output (a 1 corresponds to $matTag1, a 2 to $matTag2, and so on).

Warning

If the distance between end noes is not 0.0 a warning message will appear when the script is run. This is just a warning in case you have made a mistake as most users when they use zeroLength elements are wanting to use them in the more normal way. ZeroLength elements can be used between nodes with non-zero length.

Code Developed by: Gregory L. Fenves