ZeroLength Element

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This command is used to construct a zeroLength element object, which is defined by two nodes at the same location. The nodes are connected by multiple UniaxialMaterial objects to represent the force-deformation relationship for the element.

element zeroLength $eleTag $iNode $jNode -mat $matTag1 $matTag2 ... -dir $dir1 $dir2 ...<-doRayleigh $rFlag> <-orient $x1 $x2 $x3 $yp1 $yp2 $yp3>

$eleTag unique element object tag
$iNode $jNode end nodes
$matTag1 $matTag2 ... tags associated with previously-defined UniaxialMaterials
$dir1 $dir2 ... material directions:
1,2,3 - translation along local x,y,z axes, respectively;
4,5,6 - rotation about local x,y,z axes, respectively
$x1 $x2 $x3 vector components in global coordinates defining local x-axis (optional)
$yp1 $yp2 $yp3 vector components in global coordinates defining vector yp which lies in the local x-y plane for the element. (optional)
$rFlag optional, default = 0
rFlag = 0 NO RAYLEIGH DAMPING (default)
rFlag = 1 include rayleigh damping


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). EXAMPLE:

element zeroLength 1 2 4 -mat 5 6 -dir 1 2; # truss tag 1 between nodes 2 and 4 acting in directions 1 and 2 with materials 5 and 6 respectively.

element zeroLength 1 1 2 -mat 1 -dir 1 -orient 1 1 0 -1 1 0; # truss tag 1 between nodes 1 and 2 acting in local direction 1 defined with material 1. Local direction 1 attains 45 degrees with global X axis

element zeroLength 1 1 2 -mat 1 -dir 1 -doRayleigh 1 -orient 1 1 0 -1 1 0; # the same as the example above but also includes the stiffness of this element in calculation of the damping matrix if Rayleigh command is invoked later.

Code Developed by: Gregory L. Fenves, University of Texas, Austin.