Maxwell Material: Difference between revisions

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|The sensitivity of the viscous damper with respect to its axial stiffness is shown in Figure 2 for the following set of parameters:  K=500.0kN/mm, C=100.0kN/(mm/s)^0.3, a=0.30.
|The sensitivity of the viscous damper with respect to its axial stiffness is shown in Figure 2 for the following set of parameters:  K=500.0kN/mm, C=100.0kN/(mm/s)^0.3, a=0.30.
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| [[File:Fig1.png|350px|thumb|left|Figure 1. Viscous Damper with K=150.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30]]  
| [[File:Fig1.png|375px|thumb|left|Figure 1. Viscous Damper with K=150.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30]]  
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| [[File:Fig2.png|350px|thumb|left|Figure 2. Viscous Damper with K=500.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30]]  
| [[File:Fig2.png|375px|thumb|left|Figure 2. Viscous Damper with K=500.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30]]  
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Revision as of 18:43, 15 February 2011



This command is used to construct a Maxwell material (linear spring and nonlinear dashpot in series). The Maxwell material simulates the hysteretic response of viscous dampers.

uniaxialMaterial Maxwell $matTag $K $C $a $L
$matTag integer tag identifying material
$K Elastic stiffness of linear spring (to model elastic stiffness of viscous damper)
$C Viscous parameter of damper
$a Viscous damper exponent
$L Viscous damper length

Examples:

1. Input parameters:
Assume a viscous damper with axial stiffness K=150.0kN/mm, viscous parameter C = 100.0kN/(mm/s)^0.3, an exponent a=0.3 and length equal to 5000mm.
The input parameters for the material should be as follows:
uniaxialMaterial Maxwell 1 150.0 100.0 0.30 5000.0
Using these properties a comparison between simulated responses from OpenSees and a MATLAB based program are shown in Figure 1.
The sensitivity of the viscous damper with respect to its axial stiffness is shown in Figure 2 for the following set of parameters: K=500.0kN/mm, C=100.0kN/(mm/s)^0.3, a=0.30.
Figure 1. Viscous Damper with K=150.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30
Figure 2. Viscous Damper with K=500.0kN/mm, C = 100.0kN/(mm/s)^0.3, a=0.30
2. Tcl input file for Viscous Damper Calibration: (to be posted)
3. OpenSees Example of 1-story steel moment frame with a viscous damper: (to be posted)

References:

[1] Olsson, A.K., and Austrell, P-E., (2001), "A fitting procedure for viscoelastic-elastoplastic material models," Proceedings of the Second European Conference on Constitutive Models for Rubber, Germany, 2001.
[2] Ottosen, N.S., and Ristinmaa, M., (1999). "The mechanics of constitutive modelling, (Numerical and thermodynamical topics)," Lund University,Division of Solid Mechanics, Sweden, 1999.

Code Developed by : by Dr. Dimitrios G. Lignos (McGill University)

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