Damping ratio

Last updated: Jan 08, 2024 11:15:20
  • For dynamic modules 41 and 64, calculation of damping ratios by mode shapes (according to damping ratios specified for elements).

Note: In LIRA-SAPR 2022 R2, in analysis on accelerograms of earthquake load with dynamic modules 27 and 29 for design models consisting of elements or fragments with different damping properties, the analysis of equivalent attenuation by the j-th eigenmode of vibrations was implemented by the following formula:


where {φj} is the vector of the j-th mode shape, [K] is the stiffness matrix of the model, ∑[ξK]i is the stiffness matrix (for the i-th element or fragment) multiplied by the damping ratio for this element.

  • New option to use separately the damping ratios for each dynamic load case in the dynamic modules 27/29 and 41/64. For these modules, it is possible to limit the damping ratio: for 27 and 29 - maximum damping ratio, for 41 and 64 - minimum and maximum Nu.

Account of damping in the spectral method

Account of damping in the spectral method