ZeroLength

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 >

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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

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).

EXAMPLES:

Truss tag 1 between nodes 2 and 4 acting in directions 1 and 2 with materials 5 and 6 respectively.

element zeroLength 1 2 4 -mat 5 6 -dir 1 2;

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 -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.

element zeroLength 1 1 2 -mat 1 -dir 1 -doRayleigh 1 -orient 1 1 0 -1 1 0; 

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