I have manually generated earthquake loads. How can I combine them according to the superposition rules of the standard?


If you have defined the load cases with earthquake loads and cannot combine them by using the RF‑/DYNAM Pro add-on module, the automatic combinatorics should not be used for this. The following steps describe how to define the manual combinatorics:

  • Depending on whether you want to use the SRSS or CQC rule, it may be necessary to activate it in General Data (in the case of the CQC rule only). For the CQC rule, you have to activate the additional parameters, which can be set in the load cases.

  • Create a result combination for each direction. Add all load cases where you have defined the earthquake actions in this direction. In Calculation Parameters, you can then define the type of superposition.
  • As a next step, the directions are superimposed in further result combinations. In this case, Eurocode 8 provides the 100/30% rule, for example. For this, add "and" to the result combinations of the individual directions, and change the factors to 1.0 for the dominant direction and 0.3 for the other directions. It is necessary to always create one result combination for each direction.

  • Finally, a further result combination is created, which can then be used for the design. In this combination, the earthquake loads are superimposed with the permanent and the imposed loads (creation of an accidental combination). Please note that the result combinations for earthquakes must be added with "or".


Equivalent load Combination Earthquake Dynamics Result combination


Contact us

Contact to Dlubal

Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

+49 9673 9203 0


RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

Price of First License
3,540.00 USD
RSTAB Main Program
RSTAB 8.xx

Main Program

The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions

Price of First License
2,550.00 USD