FAQ 000244 EN-US 12/01/2017

Stefan Frenzel Calculation RF-DYNAM Pro - Forced Vibrations

In which case and which superposition expression should I use for the modal response spectrum method?

Answer

The complete quadratic combination (Complete Quadratic Combination, CQC) is used if in the analysis of spacial models with mixed torsional / translational eigenvectors there are adjacent mode shapes, whose periods differ by less than 10 %. If this is not the case, the quadratic combination (SRSS) is used.

More information can be found in the literature mentioned below.

Keywords

quadratic combination superposition expression square root of the sum of the squares SRSS CQC

Reference

[1]   Meskouris, K. (1999). Baudynamik, Modelle, Methoden, Praxisbeispiele. Berlin: Ernst & Sohn.
[2]   Eurocode 8: Design of structures for earthquake resistance - Part 1: General rules, seismic actions and rules for buildings; EN 1998‑1:2004/A1:2013

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RFEM Dynamic Analysis
RF-DYNAM Pro - Forced Vibrations 5.xx

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Dynamic and seismic analysis including time history analysis and multi-modal response spectrum analysis

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