What Is OpenSees
OpenSees is a software framework for developing applications to simulate the performance of structural and geotechnical systems subjected to earthquakes. A number of OpenSees applications are released on this website. Here is a short video.

The goal of the OpenSees development is to improve the modeling and computational simulation in earthquake engineering through open-source development.

OpenSees is under continual development, so users and developers should expect changes and updates on a regular basis. In this sense, all users are developers so it is important to register. More information on Open Source is available.

The development of OpenSees was sponsored by the Pacific Earthquake Engineering Research Center

Aug 2 and Aug 4, 2022: OpenSees Programming Bootcamp 2022
For 2022 we will be hosting an on-line Programming Bootcamp. This bootcamp will introduce users to the OpenSees framework and will demonstrate to them how to build the OpenSees applications (python and tcl) and how to add elements and materials to both interpreters. Registration is required and the attendence number is being capped as we have a limit on zoom. To this end a fee of $10 is being asked to ensure people who sign up actually attend the event.
NOTE: This bootcamp will assume a working knowledge of C/C++. Python will also be needed, if that is your OpenSees interpreter of choice. If you do not have such skills you will be lost in this bootcamp and it probably will not be worth attending as time is limited and we will not be able to help people struggling with these basics. If you do not have such skills, you will be shown the necessary skills by watching the first 3 days of materials of SimCenter Programming Bootcamp.
The format will be on-line: 2 hours of zoom which will include presentations, demo's and exercises. There will be two days of this, and for each day there will be two sessions: one in morning (8-10 am PDT) for those in timezones east of California and once in evening (5-7 pm PDT) for those in timezones to west of us.
OpenSees3.3.0
May 24, 2021: Version 3.3.0 of the OpenSees binary is now available for download.
OpenSees3.2.2
July 3, 2020: Version 3.2.2 of the OpenSees binary is now available for download.
OpenSees3.2.1
June 10, 2020: Version 3.2.1 of the OpenSees binary is now available for download.
SimCenter Workshops & Applications
June 1, 2020: The NHERI SimCenter will be holding workshops on the use of their tools. All the tools presented will help OpenSees users in their work. They all provide much needed features for OpenSees users wanting to incorporate uncertainty quantification (UQ) (and if you don't want to look at UQ in your simulation results one questions if you should be using nonlinear FEM tools in the first place!). The tools provide methods for sampling, reliability, sensitivity, parameter estimation, and bayesian calibration. For OpenSeesPy users, quoFEM is now integrated into the tool. The tool pages of interest quoFEM, EE-UQ, PBE, and for those doing wind engineering WE-UQ.
OpenSees3.2.0
March 9, 2020: Version 3.2.0 of the OpenSees binary is now available for download.
OpenSees3.1.0
November 1, 2019: Version 3.1.0 of the OpenSees binary is now available for download.
OpenSees3.0.3
April 15, 2019: Version 3.0.3 of the OpenSees binary is now available for download. Here is the change log. In the new version we update the version of Tcl that is required. For existing users this means that this will require that you uninstall Tcl and reinstall it using the latest links provided.
MDOF
MDOF is an educational application built using OpenSees for looking at response of buildings to earthquakes. The software is available through the MDOF Tool website
PileGroupTool
PileGroupTool is another educational application built using OpenSees for looking at response of pile groups in layered soil to lateral loading. The software is available through the PilGroupTool website
Build-X
Build-X, an expert system for reliable pre-and post-processing of buildings is now available for free download by the academic and research community. It is an efficient tool that utilises a wizard-like GUI to generate the tcl file and visualize the action effects of buildings under earthquake loading making expert decisions that facilitate the minimization of epistemic uncertainty. The software is available through the Build-X website
OpenSees Days Europe June 19-20, 2017
The first Euopean conference on OpenSees will be held on June 19-20, 2017 at the Faculty of Engineering of the University of Porto, Porto, Portugal. For more information, please consult the conference web page.
New Amazon Image
We have created a new Amazon Machine Image for those wishing to use the Amazon Cloud to do your analysis. This image conatins versions 2.5.0 of the sequential OpenSees application and the two parallel OpenSeesSP and OpenSeesMP applications. The image can be launched from the Amazon EC-2 Console or using starcluster. See here for details.
Updated Stampede Executables
We have updated the OpenSeesSP and OpenSeesMP applications on Stampede to version 2.5.0 for those wishing to do High Performance Paralllel Computing (HPC). These applications are available to XSEDE account holders on Stampede from the following directory: /home1/00477/tg457427/bin . In addition, for those registered on DesignSafe-ci, the applications are available through the Workspace.
OpenSees 2.5.0 Released
Version 2.5.0 of the OpenSees binary is now available for download. Here is the change log.
Amazon EC2 Image Available
We have made public an Amazon EC2 machine image that can be used to run Sequential and Parallel jobs on the cloud resources provided by Amazon EC2. With just 6 commands you could run your scripts remotely on a cluster of one to a few hundred nodes and all it would cost you is some of your free allocation or as little as $0.01 an hour per node. See here for details and here is a 5 minute video.
Survey - OpenSees Missing Pieces
We are conducting a survey to identify problems ans shortcoming associated with OpenSees. Please help by filling out the survey.
OpenSees Days 2014
NEES and PEER hosted this years two day event on September 25-26 at the Richmond field Station, UC Berkeley. The presentations are now available online and can be found here

More info...