ViscousDamper Material: Difference between revisions

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|  style="width:150px" | '''$matTag ''' || integer tag identifying material
|  style="width:150px" | '''$matTag ''' || integer tag identifying material
|-
|-
|  '''$K ''' || Elastic stiffness of linear spring (to model the axial flexibility of a viscous damper (brace and damper portion)
|  '''$K ''' || Elastic stiffness of linear spring to model the axial flexibility of a viscous damper (e.g. combined stiffness of the supporting brace and internal damper portion)
|-
|-
|  '''$Cd ''' || Viscous parameter of damper
|  '''$Cd ''' || Damping coefficient
|-
|-
|  '''$alpha ''' || Viscous damper exponent
|  '''$alpha ''' || Velocity exponent
|-
|-
|  '''$LGap ''' || gap length to simulate the gap length due to the pin tolerance
|  '''$LGap ''' || Gap length to simulate the gap length due to the pin tolerance
|-
|-
|  '''$NM ''' || Employed adaptive numerical algorithm (default value NM = 1; 1 = Dormand-Prince54, 2=6th order Adams-Bashforth-Moulton, 3=modified Rosenbrock Triple)
|  '''$NM ''' || Employed adaptive numerical algorithm (default value NM = 1; 1 = Dormand-Prince54, 2=6th order Adams-Bashforth-Moulton, 3=modified Rosenbrock Triple)
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| '''''1. Input parameters:'''''
| '''''1. Input parameters:'''''
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| Assume a viscous damper with axial stiffness K=300.0kN/mm, viscous parameter Cd=280.3kN(s/mm)<sup>0.3, and exponent a=0.30.  
| Assume a viscous damper with axial stiffness K=300.0kN/mm, damping coefficient Cd=280.3kN(s/mm)<sup>0.3</sup>, and exponent a=0.30.  
|-
|-
| The input parameters for the material should be as follows:
| The input parameters for the material should be as follows:
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| Using these properties, Figure 1 shows the hysteretic response of this damper for sinusoidal displacement increments of 12, 24 and 36mm and a frequency f = 0.5Hz.  
| Using these properties, Figure 1 shows the hysteretic response of this damper for sinusoidal displacement increments of 12, 24 and 36mm and a frequency f = 0.5Hz.  
|-
|-
|The sensitivity of the viscous damper with respect to its axial stiffness is shown in Figures 2 to 4 for the following set of parameters:   
|The sensitivity of the viscous damper with respect to its velocity exponent is shown in Figures 2 to 4 for the following set of parameters:   
|-
|-
| [[File:Fig2_ViscousDampers.png|850px|thumb|left| Viscous Damper with various input parameter variations]]  
| [[File:Fig2_ViscousDampers.png|850px|thumb|left| Viscous Damper with various input parameter variations]]  

Revision as of 02:18, 30 September 2016



This command is used to construct a ViscousDamper material, which represents the Maxwell Model (linear spring and nonlinear dashpot in series). The ViscousDamper material simulates the hysteretic response of nonlinear viscous dampers. An adaptive iterative algorithm has been implemented and validated to solve numerically the constitutive equations within a nonlinear viscous damper with a high-precision accuracy.

uniaxialMaterial ViscousDamper $matTag $K $Cd $alpha <$LGap> < $NM $RelTol $AbsTol $MaxHalf>
$matTag integer tag identifying material
$K Elastic stiffness of linear spring to model the axial flexibility of a viscous damper (e.g. combined stiffness of the supporting brace and internal damper portion)
$Cd Damping coefficient
$alpha Velocity exponent
$LGap Gap length to simulate the gap length due to the pin tolerance
$NM Employed adaptive numerical algorithm (default value NM = 1; 1 = Dormand-Prince54, 2=6th order Adams-Bashforth-Moulton, 3=modified Rosenbrock Triple)
$RelTol Tolerance for absolute relative error control of the adaptive iterative algorithm (default value 10^-6)
$AbsTol Tolerance for absolute error control of adaptive iterative algorithm (default value 10^-10)
$MaxHalf Maximum number of sub-step iterations within an integration step (default value 15)

Examples:

1. Input parameters:
Assume a viscous damper with axial stiffness K=300.0kN/mm, damping coefficient Cd=280.3kN(s/mm)0.3, and exponent a=0.30.
The input parameters for the material should be as follows:
uniaxialMaterial ViscousDamper 1 300 280.3 0.30
Using these properties, Figure 1 shows the hysteretic response of this damper for sinusoidal displacement increments of 12, 24 and 36mm and a frequency f = 0.5Hz.
The sensitivity of the viscous damper with respect to its velocity exponent is shown in Figures 2 to 4 for the following set of parameters:
Viscous Damper with various input parameter variations
2. Single story single bay frame with viscous damper

References:

[1] Akcelyan, S., Lignos, D. G., Hikino, T., and Nakashima, M. (2016). “Evaluation of simplified and state-of-the-art analysis procedures for steel frame buildings equipped with supplemental damping devices based on E-Defense full-scale shake table tests.” Journal of Structural Engineering, 142(6), 04016024. [1]
[2] Oohara, K., and Kasai, K. (2002), “Time-History Analysis Models for Nonlinear Viscous Dampers”, Proc. Structural Engineers World Congress (SEWC), Yokohama, JAPAN, CD-ROM, T2-2-b-3 (in Japanese).
[3] Kasai K, Oohara K. “Algorithm and Computer Code To Simulate Response of Nonlinear Viscous Damper” Passively Controlled Structure Symposium 2001, Yokohama, Japan (in Japanese).

Code Developed and Implemented by : Sarven Akcelyan & Prof. Dimitrios G. Lignos, (McGill University)

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