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NOTE: We |
Tips
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recommend using at least a small amount of damping |
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for modal |
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and direct-integration cases, even |
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when dampers are |
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present in the model. |
Damping, a property of the material and the structure, influences dynamic response. A certain type of damping is available for each type of load case. Within all load cases of a certain type, damping is applied consistently, though additional damping may be added to individual load cases.
- Modal damping is used for response-spectrum and modal time-history analyses. Material modal damping, also known as composite modal damping, is weighted according to element and modal stiffness. For each material, users specify a material modal damping ratio r, in which 0 < r < 1, which relates to the damping ratio of each mode.
- Viscous proportional damping is used for direct-integration time-history analysis. This property is proportional to mass and stiffness.
Hysteretic proportional damping, also mass- and stiffness-proportional, is used for steady-state and power-spectral-density analyses.
- Damping devices may also be modeled as a structural subsystem, as described in the Tuned-mass damper tutorial.
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See Also
- SAP2000 verification examples 6-005, 6-006, and 6-007 – examples which incorporate dampers and associated behaviors
- Additional information on each of these damping types may be found in the CSI Analysis Reference Manual (Chapter VI: Material Properties, Material Damping)