Truss Element

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This command is used to construct a truss element object. There are two ways to construct a truss element object:

One way is to specify an area and a UniaxialMaterial identifier:

element truss $eleTag $iNode $jNode $A $matTag <-rho $rho> <-cMass $cFlag> <-doRayleigh $rFlag>

the other is to specify a Section identifier:

element trussSection $eleTag $iNode $jNode $secTag <-rho $rho> <-cMass $cFlag> <-doRayleigh $rFlag>

$eleTag unique element object tag
$iNode $jNode end nodes
$A cross-sectional area of element
$matTag tag associated with previously-defined UniaxialMaterial
$secTag tag associated with previously-defined Section
$rho mass per unit length, optional, default = 0.0
$cFlag consistent mass flag, optional, default = 0
cFlag = 0 lumped mass matrix (default)
cFlag = 1 consistent mass matrix
$rFlag Rayleigh damping flag, optional, default = 0
rFlag = 0 NO RAYLEIGH DAMPING (default)
rFlag = 1 include Rayleigh damping


  1. The truss element DOES NOT include geometric nonlinearities, even when used with beam-columns utilizing P-Delta or Corotational transformations.
  2. When constructed with a UniaxialMaterial object, the truss element considers strain-rate effects, and is thus suitable for use as a damping element.
  3. The valid queries to a truss element when creating an ElementRecorder object are 'axialForce,' 'forces,' 'localForce', deformations,' 'material matArg1 matArg2...,' 'section sectArg1 sectArg2...' There will be more queries after the interface for the methods involved have been developed further.
  4. For backward compatibility the command 'element truss $eleTag $iNode $jNode $secTag will still work and produce a TrussSection element.
  5. There was an inconsistency in the way damping was treated between element types before version 2.2.0. Before 2.2.0, a Truss DID NOT INCLUDE Rayleigh damping, a TrussSection did. By default they both DO NOT now include Rayleigh damping by default.


element truss 1 2 4 5.5 9; # truss element with tag 1 added between nodes 2 and 4 with area 5.5 that uses material 9

Code Developed by: fmk