Much More in FLAC3D 6.0

Zone Relax

Creates and modifies a special APPLY condition on the zones in a specified range. This condition gradually "excavates" the material by reducing the stiffness, stresses, and densities of the zones. This keeps spurious inertial effects in the static solution process from causing unrealistic damage to the region around the excavation, especially when in weak material or high stress simulations.

The values of these quantities are systematically reduced by applying a multiplier (the reduction factor) that varies from 1.0 to 0.0 over time. The precise time taken and shape of the relaxation curve is controllable by the user, but defaults to a servo controlled by the current mechanical force ratio. When the reduction factor reaches zero, the mechanical constitutive model for the zones is set to null and the APPLY condition for these zones is removed. When all the zones involved in a given condition are nulled, the APPLY condition itself is automatically removed.

Dynamic Input Wizard

The Dynamic Input Wizard tool facilitates the preprocessing of input signals necessary to correct signal input for use in seismic and dynamic analyzes. The wizard includes the following functionality.
  • Import ground motion data (velocity or acceleration) from a FLAC3D history, FLAC3D table, or PEER file, and specify data units. 
  • Filter ground motion data to remove high-frequency components with a specified cut-off frequency. 
  • Add a baseline correction for velocity or displacement drift by removing the mean acceleration, the running average displacement, a polynomial fit displacement, or a low-frequency sine function from the acceleration or velocity. 
  • Export processed data (acceleration, velocity, displacement, amplitude spectrum, response spectrum, or Arias intensity) as a FLAC3D history or FLAC3D table file.

Westergaard Hydrodynamic Pressure

The dynamic interaction between water in a reservoir and a concrete dam can have a significant influence on the performance of the dam during an earthquake. Westergaard (1933)* established a mathematical basis for procedures to represent this interaction, and this approach is commonly used in engineering practice for stability analysis of smaller dams and preliminary calculations in the design of large dams. In FLAC3D, the inertial effects of the hydrodynamic pressure can now be included as a boundary condition by means of the Westergaard scaling of the gridpoint mass on the upstream face of the dam.

Improved Dynamic Multi-stepping

The maximum stable timestep for dynamic analysis is determined by the largest material stiffness and smallest zone in the model. Therefore, it can be that a few zones will then determine the critical timestep for a dynamic analysis, even though the major portion of the model can be run at a significantly larger timestep. The implementation of the dynamic multi-stepping procedure in previous versions of FLAC3D reduced the computation time required for dynamic calculations. In Version 6, this procedure has been improved so that it is more even more efficient when using multi-threaded calculations. The overall effect of dynamic multi-stepping on calculation speed is model-dependent, but is most dramatic (4x or more faster) for models with a very small region of much stiffer material – either structural elements or zones.

Results Files

Results files are stripped-down save files containing only user-selected data. These:

  • can be generated manually or automatically during cycling,
  • are about 5% of the size of a full save file in the case of large models,
  • are useful for sharing results with colleges and clients and for archiving work, and
  • cannot be used to cycle the simulation any further.

The Options Dialog provides controls to specify what parts (histories, zones, geometry, etc.) of the model are included in results files and how frequently they are to be generated during cycling.

For example, during a dynamic analysis, the regular save files can be saved less often, say each 20 seconds of shaking, and result files more often, say every 2 seconds if tracking the evolution of certain fields (e.g., displacement or velocity fields) is important or if you plan to create a movie animation of the model results.

Improved User Interface and Visualization

  • Multhreaded zone plots for much faster plot generation
  • Improved Control Panel with top-down, contextual control sets
  • Built-in file browser shows all files in the project (and other) directories
  • Better support for floating panes – including a local control panel for floated panes
  • Option to embed toolbar in the pane
  • Better control of the view camera, including pre-defined views, saving custom views, and locking views
  • Streamlined plot-item selection and control
  • Copy-and-paste of: plot items, cutting planes, and clip boxes
  • Drag plot items to reorder their display

Improved Built-in Text Editor

  • Improved syntax highlighting
  • Line numbering
  • Columnar selection
  • Undo
  • Updated Find/Replace dialog
  • Code Folding (collapse and expand segments of code)
  • Automatic formatting option
  • Improved on-screen help to help users write commands and FISH scripts

Improved Movie Creation

  • Wizard added to automatically generate movie frames given a list of plots and a list of save or result files
  • Pre-defined image sizes have been added to the bitmap output options for movie frame generation 

Still More ...

  • Updated save/restore system. Enhancements will allow for backward compatibility of SAV files in future versions of FLAC3D
  • Security logic enhancements:
      + specifying a particular key on the server when using a network license
      + searching for code and option matches (better key matching when multiple keys are present)
      + better error messages and feedback when key errors occur
      + ability to have multiple licenses on a single USB key
  • New technical support dialog added to the HELP menu.


*Westergaard, H. M. “Water Pressure on Dams During Earthquakes,”Proceedings of ASCE, Transactions number 98, Vol. 59, No. 8, Part 3 (1933).