Earthquake RSA reloaded¶
The SSD task Earthquake RSA reloaded calculates the eigenmodes of the structure, uses the Response Spectra Analysis to define seismic actions and calculates seismic load cases for the modal response superpostion of these actions. A variety of tools, e.g., loadtomassconvertion, modal damping or shear stiffness reduction account for specific boundary conditions.
The task consists of the following tabs:
Hint
Using a new module called FEABENCH
for certain calculation steps, this task offers more options to save resources and shows severe performance improvements.
Note
To support established earthquake workflows prior to SOFiSTiK 2022, both the new Earthquake RSA reloaded and the legacy task Earthquake coexist for the time being.
Eigenmodes and Actions¶
Define settings for the calculation of eigenmodes and seismic actions.
This tab consists of the following group boxes:
Eigenmodes¶
General, Solver Settings¶
Specifiy the maximum number of eigenmodes and the storage load case number, as well as the computational method used for the calculation.
See also
See the FEABENCH manual for more info.
Damping, Stiffness and Inertial Effects¶
Adjust modal damping and shear stiffness globally or individually by group. In addition, utilise Inertial Effects to consider or ignore acceleration and mass effects for specific groups.
It is possible to leave cells empty in the secondary groups table, thus leaving the properties unchanged from the settings made in the primary group table.
Note
Primary groups
Each structural element can belong to exactly one primary group. Therefore, the order of the primary groups is unimportant because conflicting settings cannot be made. Individual group settings override the All Groups setting.
Secondary groups
Additionally, structural elements can belong to multiple secondary groups. Therefore, the group settings will be handled from top to bottom, meaning that the bottommost setting overrides earlier ones, including primary group settings.
Filtering¶
New filter options to minimize the number of eigenmodes and hence calculation time, are available. The filter for total mass participation is set to 90% and activated by default. Alternatively, it is possible to filter out all eigenmodes with a mass participation smaller than a specified percentage. In addition, vertical eigenmodes can be eliminated.
LoadtoMass Conversion¶
Choose which load cases to consider for the recalculation of the centre of mass.
Actions¶
Direction and Accidential Eccentricity¶
Choose the direction for excitation and optionally the accidental eccentricity based on the extent of the storey.
Combination of the Effects of the Directional Components of the Seismic Action¶
Choose the method for the combination of the effects of the directional components to create seismic actions.
Method 
Norm 

SRSS 
EN 19981 :2004, 4.3.3.5.1 (2) and 4.3.3.5.2 (4) 
Newmark 
EN 19981 :2004, 4.3.3.5.1 (3) and 4.3.3.5.2 (4) 
Results¶
Define the resulting seismic action load cases which can later on be considered during the superpositioning for your design combinations.
See also
This interface utilises the following modules. For further information, see the respective documentation:
Module 
Use cases 
Documentation 

FEABENCH 
Recalculation of centre of mass, calculation of Eigenmodes 

SOFiLOAD 
Definition of Response Spectras, Renaming of load cases 

DYNA 
Calculation of spectras 