Truss Element: Difference between revisions

From OpenSeesWiki
Jump to navigation Jump to search
No edit summary
No edit summary
 
(2 intermediate revisions by the same user not shown)
Line 6: Line 6:


{|  
{|  
| style="background:lime; 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>'''
|}
|}


Line 13: Line 13:


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


Line 32: Line 32:
| '''$secTag''' || tag associated with previously-defined Section
| '''$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
|-
|-
| '''$rFlag''' || optional, default = 0
| '''$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 = 0 NO RAYLEIGH DAMPING (default)
|-
|-
| ||   rFlag = 1 include rayleigh damping
| || rFlag = 1 include Rayleigh damping
|}
|}


Line 47: Line 53:
# When constructed with a UniaxialMaterial object, the truss element considers strain-rate effects, and is thus suitable for use as a damping element.
# 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,' '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.
# 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 compatability the command '''element truss $eleTag $iNode $jNode $secTag'' will still work and produce a TrussSection element.
# For backward compatibility the command '''element truss $eleTag $iNode $jNode $secTag'' will still work and produce a TrussSection element.
# There was an inconsistancy 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.
# 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:

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

Retrieved from "https://opensees.ist.berkeley.edu/wiki/index.php?title=Truss_Element&oldid=11358"