There are two solving methods for a linear time history analysis available in the RF‑/DYNAM Pro add-on module. What is the difference between them?

Answer

Both solving methods, the "linear modal analysis" and the "linear implicit Newmark analysis," are available.

Linear Modal Analysis

This solving method uses a decoupled structure that is based on eigenvalues and mode shapes of the structure. It is necessary to assign a defined natural vibration case.

This method should only be used if there is a sufficient number of eigenvalues of the structure calculated in the natural vibration case. This means that you should pay attention to achieve an effective modal mass factor of the total structure of approximately 1 in all governing directions. If this is not possible, this method will lead to inaccurate results.

Linear Implicit Newmark Analysis

This is a direct time step method that does not require a natural vibration case, and requires enough small time steps to achieve the exact results.

This method is recommended for complex structures, which would require a very large number of mode shapes in order to achieve an effective modal mass factor of about 1.

If a sufficient number of eigenvalues can be guaranteed by means of the linear modal analysis, both solving methods lead to approximately same results. For more information about both methods, read the manual of RF‑DYNAM Pro.

Keywords

Solving method Solver Time history Newmark Modal analysis

Reference

Downloads

Write Comment...

Write Comment...

  • Views 76x
  • Updated 8 November 2020

Contact us

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

info@dlubal.com

Online Training | English

Eurocode 3 | Steel structures according to DIN EN 1993-1-1

Online Training 8 December 2020 8:30 AM - 12:30 PM CET

Online Training | English

RFEM | Steel Basics

Online Training 8 December 2020 9:00 AM - 12:00 PM EDT

Online Training | English

RFEM | Structural dynamics and earthquake design according to EC 8

Online Training 10 December 2020 8:30 AM - 12:30 PM CET

Online Training | English

RFEM for Students | Part 3

Online Training 11 December 2020 3:00 PM - 6:00 PM CET

Dlubal Info Day

Dlubal Info Day Online | 15 December 2020

Webinar 15 December 2020 9:00 AM - 4:00 PM CET

Online Training | English

Eurocode 2 | Concrete structures according to DIN EN 1992-1-1

Online Training 17 December 2020 8:30 AM - 12:30 PM CET

Online Training | English

Eurocode 5 | Timber structures according to DIN EN 1995-1-1

Online Training 18 December 2020 8:30 AM - 12:30 PM CET

Stability Design in Steel Construction with RFEM and RSTAB

Stability Design in Steel Construction with RFEM and RSTAB

Webinar 1 December 2020 2:00 PM - 2:45 PM CET

FEA debugging and optimization in RFEM

FEA Troubleshooting and Optimization in RFEM

Webinar 11 November 2020 2:00 PM - 3:00 PM

Soil-Structure Interaction in RFEM

Soil-Structure Interaction in RFEM

Webinar 27 October 2020 2:00 PM - 2:45 PM CET

NBC 2015 Modal Response Spectrum Analysis in RFEM

Webinar 30 September 2020 2:00 PM - 3:00 PM EDT

Documenting Results in the RFEM Printout Report

Documenting Results in the RFEM Printout Report

Webinar 25 August 2020 2:00 PM - 2:45 PM CEST

ACI 318-19 Concrete Design in RFEM

Webinar 20 August 2020 2:00 PM - 3:00 PM EDT

How to Be More Productive Using RFEM

How to Be More Productive Using RFEM

Webinar 7 July 2020 3:00 PM - 4:00 PM CEST

Introduction to Solid Modeling \n in RFEM

Introduction to Solid Modeling in RFEM

Webinar 30 June 2020 2:00 PM - 3:00 PM EDT

Modeling with Solids in RFEM

Modeling with Solids in RFEM

Webinar 9 June 2020 3:00 PM - 3:45 PM CEST

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

Add-on Module

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

Price of First License
1,120.00 USD