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NonlinPro: Pre and Post-Processor for Drain-2DX

NonlinPro is a pre and post-processor for DRAIN-2DX (a computer program for static and dynamic analysis of plane structures).

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Version 6.42 - published on 06 Oct 2011

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NonlinPro is a pre and post-processor for the well-known structural analysis program DRAIN-2DX.  NonlinPro includes a powerful preprocessing environment for graphically creating input files for the DRAIN-2DX analytical engine.  After the model is developed, it may be analyzed and sent to the postprocessor for review and evaluation. While DRAIN-2DX is an excellent tool for nonlinear analysis, it is not very user friendly.  Once you have created an input file, it is difficult to check.  And after the program runs, it can take hours to obtain plots and other essential information.  Even when plots are obtained, interpretation of results is hampered by a lack of essential data analysis tools. NonlinPro was designed specifically to overcome the shortcomings of DRAIN-2DX.  With NonlinPro, you can graphically view the structure defined by the input file, and create and print a wide variety of plots of DRAIN-2DX output.  You can also create output that is not directly available from DRAIN-2DX, such as total floor acceleration and inertial forces.  NonlinPro even has utilities for creating Elastic Response Spectra of the input ground motion, Fourier Amplitude Spectra of response histories, and Response Spectra of any computed acceleration time history (including floor spectra).  A series of additional tools supplied with the program provide stand-alone utility as well as some interaction with NonlinPro.

While still in the NonlinPro environment, NonlinPro lets the user do the following:

  • View and edit the DRAIN2DX input file.
  • View the structural topology, including undeformed shape, restraints, slaving, masses, and nodal loads.
  • Obtain information on nodes or elements by pointing to the node or element with the mouse, and then clicking once. This can be done either in a “Review Mode” or in an “Analysis Mode.” The former provides general structural information, such as nodal coordinates, and also allows the definition of Combos.  The latter provides the results from an analysis, such as a time-history of a nodal velocity.
  • Plot earthquake accelerograms, and obtain Fourier Amplitude Spectra and Response Spectra.
  • Run DRAIN-2DX.
  • View all DRAIN-2DX output files.
  • Plot and animate mode shapes.
  • Plot time-histories of nodal displacements, velocities and accelerations.  For earthquake problems, time histories of the total acceleration may also be obtained.
  • Plot time histories or xy plots of element results .   For those elements with a viscous force component, NonlinPro allows for the plot of the total member force (elastic plus damping).
  • Plot time histories or x-y plots of Combo results (such as story drifts, shears, and moments).
  • Obtain an on screen display of a Fourier Amplitude Spectra for any time-history.
  • Obtain a tab-delimited file for any time-history shown that can be saved to disk for further processing on EXCEL or other spreadsheet type programs.
  • For any plot shown by NonlinPro, a printer plot can be obtained by at most two mouse clicks.
  • NonlinPro also has powerful tools for performance based earthquake engineering.  Included in the tools are ATC 40 and FEMA 273 compliant static pushover analysis.

   Below is a screen shot showing the combos plot obtained from NonlinPro representing the inertial forces at each story, and the total of the entities is the total base shear, including the effects of viscous damping.

 Most of operations available to the NonlinPro are accessed through the menu system.  The menu has twelve main segments.  The main menu segments are as follows:

File : Create a new preprocessor file, save a new preprocessor file, and open an existing pre or postprocessing file.
Parameters : Set certain program parameters, such as node display size, and load and mass scaling.
Grid : Activate and control a grid useful for creating new models.  Nodes may be snapped to the grid.
Display : Turn on or off node and element labels, restraint, slaving, mass, and load symbols.  Most of the controls on the Display menu are accessible through the toolbar.
Topology : After a basic rectilinear or free-form model is created through the initial structure wizard, the controls in the topology menu, together with graphic selection, are used to add, modify, or delete elements or nodes.  Some of these features are very powerful.      
Nodal Assignments : Nodal restraints, masses, and slaving, are created through this menu.
Property Definitions : Element stiffness and hysteretic parameters are defined here, as are beam-column element rigid end zones.  Element property files may be saved for use in future problems.
Elemental Assignments : Element Types and groups are assigned through this menu, and element properties are assigned to the different elements within each group.  The element properties themselves are created through the Property Definition menu.
Static Loads : Nodal load patterns defined through this menu.  Element load option is currently off.
Dynamic Loads : Acceleration, displacement, and nodal load time histories are selected and scaled  in this section.  The records may be viewed in time-history format, and their elastic response spectra or Fourier Amplitude spectra may be plotted through a single mouse click. The NonlinPro program comes with more than 20 pre-defined acceleration time histories (.acn files). In addition to the .acn files, .nga files are also compatible with the current version of NonlinPro.
Analysis Control : DRAIN-2DX analysis segments are set up through the use of this menu item.  Gravity, Static, Modal, and Dynamic Time History analysis segments may be created, and then selected for use in a particular analysis session.
Help : The Help menu item provides help for the entire NonlinPro environment.

For further information, please consult the help guide posted under attachments.



Developed by Finley A. Charney

Virginia Polytechnic Institute and State University

Department of Civil and Environment Engineering

200 Patton Hall

Virginia Tech, Blacksburg, VA 24061  USA


Cite this work

Researchers should cite this work as follows:

  • (2011), "NonlinPro: Pre and Post-Processor for Drain-2DX,"

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