ops_vis module¶

ops_vis is an OpenSeesPy postprocessing and plotting module written by Seweryn Kokot (Opole University of Technology, Poland).

This module can be mainly useful for students when learning the fundamentals of structural analysis (interpolated deformation of frame structures (static images or animations), section force distribution of frame structures, stress distribution in triangle, quadrilateral 2d elements, orientation of frame members in 3d space, fibers of a cross section, static and animated eigenvalue mode shapes etc.). This way, we can lower the bar in teaching and learning OpenSees at earlier years of civil engineering studies. However the visualization features for OpenSees can also be helpful for research studies.

Note that OpenSeesPy contains another plotting module called Get_Rendering, however ops_vis is an alternative with some distinct features (on the other hand the Get_Rendering has other features that ops_vis does not have), which for example allow us to plot:

  • interpolated deformation of frame structures,
  • stresses of triangular and (four, eight and nine-node) quadrilateral 2d elements (calculation of Huber-Mieses-Hencky equivalent stress, principal stresses),
  • fibers of cross-sections,
  • models with extruded cross sections
  • animation of mode shapes.

To use ops_vis in OpenSees Python scripts, your .py file should start as follows:

import openseespy.opensees as ops
import openseespy.postprocessing.ops_vis as opsv
import matplotlib.pyplot as plt
# ... your OpenSeesPy model and analysis commands ...
opsv.plot_model()
sfac = opsv.plot_defo()

The main commands related to various aspects of OpenSees model visualization are as follows:

  1. plot_model (ops_vis)
  2. plot_defo (ops_vis)
  3. plot_mode_shape (ops_vis)
  4. section_force_diagram_2d (ops_vis)
  5. section_force_diagram_3d (ops_vis)
  6. plot_stress_2d (ops_vis)
  7. ops_vis_plot_extruded_model_rect_section_3d
  8. anim_defo (ops_vis)
  9. anim_mode (ops_vis)
  10. plot_fiber_section (ops_vis)

Helper functions include:

  1. fib_sec_list_to_cmds (ops_vis)
  2. sig_out_per_node (ops_vis)

Notes:

  • matplotlib’s plt.axis('equal') does not work for 3d plots therefore right angles are not guaranteed to be 90 degrees on the plots
  • plot_fiber_section is inspired by Matlab plotSection.zip written by D. Vamvatsikos available at http://users.ntua.gr/divamva/software.html