STKO | Scientific ToolKit for OpenSees |

STKO (Scientific ToolKit for OpenSees) is a powerful pre and post processor and cutting-edge data visualization tool for Opensees. By using STKO a user can create a Tool Command Language (TCL) input file for Opensees and an output file readable by its graphic interface. The user can customize and manipulate with a Python-based scripting interface the model input and output to create customized engineering demand parameters and output data.


Post processing of shell results at gauss points and at through-the-thickness integration points (fibers).

Post processing of beam-column results by means of a fiber-section plot, that allows the user to visualize results such as strain/stress at each fiber of each gauss points of beam-column elements.

Meshing algorithms in STKO pre-processor. Global and local edge seed, unstructured and structured mesh algorithms, triangle/tetrahedron, quadrilateral/hexahedron, linear and quadratic interpolations.

Post processing of beam-column results by means of a gauss-point plot, that allows the user to visualize results such at each gauss points of beam-column elements.

STKO pre-processing for micro-modeling of masonry structures

STKO Seismic Isolation


Post-processing of a soil-foundation-structure-interaction problem. Visualization of results on solid elements by means of a volume plot.

Example of absorbing boundaries using the VS3D4 element available in OpenSees.

Comparative study of different approches to simulate absorbing boundaries in soil-structure interaction problems.

3D Analysis of Soil-Pile interaction with contact elements.

Simulation SFSI (Soil Foundation Structure Interaction). Courtesy of Jenny Ramirez Calderon – PhD thesis

SFSI: Analysis of the boundary conditions and their application in the case study of a bridge | courtesy of Luca Sallese - master degree |

WHY Scientific ToolKit for Opensees IS SO INNOVATIVE


… features advanced CAD modeling tools, import-export of common CAD file formats, geometry repair tools, and a comprehensive set of meshing algorithms.

… is easily customizable via a python-based scripting interface. So custom components can be easily specified and added to the standard document, to fit the end-user needs.

… can then produce input files for OpenSees with all the information inputed by the user.


Import-export of open file formats (STEP and IGES)

Curve modeling

Surface modeling

Solid modeling

Interface modeling



Linear | Quadratic


Edge Seed:

Uniform by divisions

Uniform by size

Biased by size and bias factor

Biased by number and bias factor

Dual-biased by size and bias factors


2D un-structured for triangles and quadrilaterals

3D un-structured for tetrahedrons

2D structured for triangles and quadrilaterals

3D structured for hexahedrons



Uniaxial | nD



Beam fiber-section

Shell layered-section


SP constraints

MP constraints


Uniform exitation pattern

Multi-support exitation pattern






… features all common visualization algorithms (edge/surface color map, volume rendering, iso-lines, iso-surfaces, vector plots, etc..). Post processing also includes advanced visualization algorithms for beam/column and shell elements equipped with discretized (fiber) cross sections.

… is easily customizable via a python-based scripting interface. Therefore, results can be estracted and manipulated using custom python-scripts, allowing the end-user to produce custom information.

Finally, STKO uses an efficient opensource third-party database library for storing results. The MPCORecorder is a new recorder class for OpenSees that allows OpenSees to write results data in the format required by STKO.

All these features in one Software: STKO, a revolutionary visualization toolkit for Opensees


Save/Load existing post-processor files (restore plots, charts, etc.)

Import of one or multiple MPCO output databases


Deformed shape

Surface color map

Volume color map

Gauss-point plot

Beam/Shell fiber-section plot

Vector plot

Iso-surface plot



Extract chart data from database:

From nodes

From gauss points

From fibers

2D Charts


Python scripting interface

STKO provides the HDF5 database library on standard and advanced visualization techniques in post-processing and the structure of the proposed file format.

It most of all includes Python-based scripting interface for manipulation and customization of results and the implementation of the new recorder class in OpenSees. STKO shows numerical applications. It also provides examples of soil-structure interactions, visualization of beam and shell data defined at gauss and at sub-integration points. Moreover the management of output database via user-defined scripts, extrapolation and manipulation of data for production of new custom results.

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