Response Spectrum Analysis
and Equivalent Load Analysis

You need the Modal Analysis add-on as well. It determines the natural frequencies, mode shapes, and effective modal masses, which the response spectrum analysis then scales and superimposes. The two add-ons are usually purchased together, and the modal analysis load case is created in the same dialog as the seismic one.

Most likely, yes. EN 1998-1 has more than 25 National Annexes, and there are separate implementations for ASCE 7, IBC, NBC, NTC, NTC CDMX, CFE Sismo, CIRSOC 103, NSR-10, NCh 433, NCSE, NPR 9998, P 100-1, SANS 10160-4, SBC 301, TBEC, IS 1893, GB 50011, SIA 261, AS 1170.4, DIN 4149, and DTR-BC 2-48. The complete list of all editions is available on the Standards page.

Yes, you can. In addition to the standard spectra, you can enter a user-defined spectrum point by point, or you can generate one from an accelerogram. The add-on includes a library of recorded earthquakes, and you can import your own acceleration record.

Yes, they are. The program uses the Combination Wizard to create the seismic design situation and the associated result combinations, which are available in the concrete, steel, timber, and aluminum design add-ons. You do not have to rebuild the seismic combinations manually.

Yes, with the Building Model add-on. Once the stories are defined, the seismic results are output for each story, including the center of mass, center of rigidity, shear force, displacements, interstory drifts, and sensitivity coefficients. This information is also used to check drift limits and determine the need for a second-order analysis.

Yes, it is. Both RFEM 6 and RSTAB 9 have the response spectrum analysis, with the same standards and combination rules. RFEM 6 also supports surface and solid models, which is important for shear wall buildings and slab structures. Currently, the Equivalent Load Analysis is only available in RFEM 6.

No, once you select a seismic standard in the model's base data, the input dialog boxes adjust to it, and the program proposes the parameters required by that standard. You enter the values from your seismic report or national annex. However, interpreting the results still requires engineering judgment. The technical articles below provide complete examples.

Multi-modal methods are available today, including response spectrum analysis and equivalent load analysis based on mode shapes. Simplified procedures, such as the equivalent lateral force procedure and the lateral force method of analysis according to EN 1998-1, ASCE 7, and NBC, are being developed and will be included in the same add-on.