Motivation

First I wrote a Pascal version of the program which only worked with bar-type elements. Then I wrote a C++ version “from scratch” that was never able to solve any nontrivial problem. Finally, I discovered the possibilities offered by the calculation core of Opensees and decided to modify it to be suitable for an “industrial environment” (as opposed to academic use)».

Luis C. Pérez Tato.

To achieve this objective, several significant modifications to the original code were required:

- - Python language was adopted to expose C++ classes to the user. This way the user can take advantage from the enormous amount of scientific and technical libraries developed in Python.
- - The Python interface makes possible to interpret a sentence like “get the ratio between the vertical displacement of the node closest to the center of the beam and the total span of the beam”.
- - We added algorithms to enable mesh generation allowing the modeler to create structured grids from the description of geometry by means of points, lines, surfaces and solids.
- - Graphics were generated using the VTK library. The Python interface makes possible to obtain the results produced by the calculation without having to extract them from predefined listings. Utilities for the construction and calculation of design load combinations prescribed by the building codes (EHE, ACI 318, EAE, Eurocodes, etc.) were implemented to facilitate the verification of design requirements.
- - The ability to activate and deactivate elements was introduced to enable the analysis of structures built in phases, geotechnical problems, and the strengthening of existing structures.
- - Macros were written to verify the structure and its elements according to the criteria prescribed by building codes (e.g. axial and bending capacity, shear reinforcement).
- - The code was changed to link with “standard” linear algebra libraries (e.g. BLAS, Arpack, LAPACK, SuperLU), eliminating the need to include in the program “ad-hoc” versions of these libraries.
- - The material models were modified to support prescribed strains, making it possible to solve problems involving thermal and rheological actions.

- - Analysis of prestressed concrete structures with XC. Part I.- Immediate losses in prestress.
- - Analysis of tensegrity structures with XC.
- - Analysis of a vibrating string under tension with XC.
- - Analysis of a building with XC.
- - Implementation of a tension-stiffening model for the cracking nonlinear analysis of reinforced concrete elements in XC.
- - Implementation of interaction diagrams in XC.
- - One year ago, I joined the crew.
- - Hacking structural analysis. Join the crew.
- - On how XC utilizes VTK. Article published in the magazine
*Kitware SOURCE - Software developer's quarterly*Oct. 2010 - - Generation of combinations to be considered in the structural calculation.
- - Applications of XC in the development of R & D projects in the construction area.
*(in Spanish)* - - Free software for the structural analysis using the finite element method. Article published in the magazine
*Comercio e industria de la madera*(in Spanish) - - Applications of XC in the structural design.
*(in Spanish)* - - Mast and tower design.
*(in Spanish)* - - The earthquake and its spectrums.
*(in Spanish)* - - Introduction to compiling in Unix environment.
*(in Spanish)* - - Steel sections classification.
*(in Spanish)* - - Analysis of composite sections using fiber models.
*(in Spanish)*