Time History Analysis

There are two options. If you select the Linear Modal method, the mass matrix definition is taken from the modal analysis. For all other methods, select a load case or combination and define the mass matrix settings in the Time History Analysis settings.

It depends on the selected analysis method. Only linear methods allow you to select between Lehr's damping (constant) and Rayleigh damping. All other methods use the Rayleigh model.

You can perform two analysis types:

• Accelerogram: Model the base-excitation response for any structure, using your own earthquake record or one from the seismic event library.
• Time Diagram: Describe a load over time using either a function or tabular values.

The add-on lets you simulate a wide variety of analyses directly within your RFEM 6 model:

• Earthquake analysis (accelerograms): Simulate base-excitation problems using your own earthquake recordings or events from the library.
• Blast analysis: Use time functions to represent shock wave propagation.
• Machine-induced vibrations: Define time-dependent excitation functions to represent machine effects.
• Moving loads: Create moving load scenarios and integrate them into time-dependent load combinations.

The main difference is how nonlinearities are considered. In linear analysis, the stiffness matrix remains constant. In a nonlinear analysis, the stiffness matrix is recalculated at each step to evaluate whether a condition that activates a nonlinearity is satisfied.

• Linear methods: Linear modal and linear implicit Newmark (RFEM and RSTAB)
• Nonlinear methods: Nonlinear implicit Newmark in RFEM and nonlinear explicit (geometrically linear and large deformation) in RSTAB