Truss Element: Difference between revisions

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


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{|  
{|  
| style="background:yellow; color:black; width:800px" | '''element truss $eleTag $iNode $jNode $A $matTag <-rho $rho> <-doRayleigh $rFlag>'''
| style="background:lime; color:black; width:800px" | '''element truss $eleTag $iNode $jNode $A $matTag <-rho $rho> <-cMass $cFlag> <-doRayleigh $rFlag>'''
|}
|}


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{|  
{|  
| style="background:yellow; color:black; width:800px" | '''element trussSection $eleTag $iNode $jNode $secTag'''
| style="background:lime; color:black; width:800px" | '''element trussSection $eleTag $iNode $jNode $secTag <-rho $rho> <-cMass $cFlag> <-doRayleigh $rFlag>'''
|}
|}


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| '''$secTag''' || tag associated with previously-defined Section
| '''$secTag''' || tag associated with previously-defined Section
|-
|-
| '''$rho''' || optional, mass per unit length, default = 0.0
| '''$rho''' || mass per unit length, optional, default = 0.0
|-
| '''$cFlag''' || consistent mass flag, optional, default = 0
|-
| || cFlag = 0 lumped mass matrix (default)
|-
|-
| '''$rFlag''' || optional, default = 0
| || cFlag = 1 consistent mass matrix
|-
| '''$rFlag''' || Rayleigh damping flag, optional, default = 0
|-
|-
| || rFlag = 0 NO RAYLEIGH DAMPING (default)
| || rFlag = 0 NO RAYLEIGH DAMPING (default)
|-
|-
| ||   rFlag = 1 include rayleigh damping
| || rFlag = 1 include Rayleigh damping
|}
|}


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NOTE:
NOTE:


*When constructed with a UniaxialMaterial object, the truss element considers strain-rate effects, and is thus suitable for use as a damping element.
# The truss element DOES NOT include geometric nonlinearities, even when used with beam-columns utilizing P-Delta or Corotational transformations. 
 
# When constructed with a UniaxialMaterial object, the truss element considers strain-rate effects, and is thus suitable for use as a damping element.
*The valid queries to a truss element when creating an ElementRecorder object are 'axialForce,' 'stiff,' deformations,' 'material matArg1 matArg2...,' 'section sectArg1 sectArg2...' There will be more queries after the interface for the methods involved have been developed further.
# 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.
 
# For backward compatibility the command '''element truss $eleTag $iNode $jNode $secTag'' will still work and produce a TrussSection element.
# 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.


EXAMPLE:
EXAMPLE:
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----
----


Code Developed by: <span style="color:blue"> fmk </span>
Code Developed by: <span style="color:blue"> fmk </span>

Latest revision as of 01:40, 22 August 2014



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


NOTE:

  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.

EXAMPLE:

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

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