This window allows you to set the modal analysis options.

Pressing “OK” will cause the analysis to run. If you don’t want the analysis to run after saving this window, disable the “Analyze Model” component or set the “Run” flag to false.

Modal Analysis Options

1. Mass Source
   1. Include Element Self Mass: Check this box to include element self mass in the mass source.
   2. Include Element Additional Mass: Check this box to include element additional mass in the mass source. NOT IMPLEMENTED YET.
   3. Include Vertical Mass: Check this box to include translational mass in the vertical (global Z-direction) direction. Uncheck this to include only horizontal translational mass, which will reduce “flutter” modes and is generally acceptable for most building structures.
   4. Gravity: The acceleration due to gravity. This is used for all eigenvalue and response spectrum analyses.
   5. Global Self Mass Multiplier: Multiplies all element self mass by this value. Individual element mass multipliers (set at the element level) stack on top of this.
2. Load Patterns
   1. Include Load Patterns in Mass: Check this box to enable the inclusion of applied loads in the lateral mass.
   2. Load Pattern Table:
      1. Name: Name of the load pattern.
      2. Included: Check to include the specific load pattern in the mass.
      3. Factor: The multiplier to apply to the loads for inclusion in mass.
   3. NOTE: Including load patterns does not include self-mass, even if the load pattern has self-weight included in the pattern. To include self-mass, “Include Element Self Mass” must be checked.
3. Mass Matrix
   1. Allows user to switch between lumped and consistent mass matrices. ONLY LUMPED MASS MATRIX IS CURRENTLY IMPLEMENTED.
4. Modal Options
   1. Run Modal Analysis: Check this box to run an eigenvalue analysis.
   2. Number of Modes to Run: Number of modes to compute.