Arup and the NHERI SimCenter, an NSF-funded center dedicated to accelerating innovation and technology transfer in natural hazards engineering, have aligned efforts to advance the field of post-earthquake functional recovery simulation with the release of the Resilience-Based Design Initiative (REDi™) Seismic Downtime Model.

The release is made through PyREDi, an open-source Python package that implements the latest version of Arup’s REDi Seismic Downtime Model, which is available at Arup’s GitHub repository. It is also accessible in an updated version of the SimCenter’s Performance-Based Engineering (PBE) Application, marking a significant contribution to the engineering and disaster resilience communities.

The REDi guidelines were developed by Arup to provide owners, architects, and engineers a framework for resilience-based design for earthquakes, extreme storms, and flooding. This launch provides open access to the official REDi Seismic Downtime Model, allowing practitioners to evaluate the resilience of their building designs, and enabling researchers to better understand and simulate the recovery of buildings and communities after earthquakes. The REDi Seismic Downtime Model can be employed for risk assessment due to its inherent probabilistic nature, making it well-suited for integration into various risk frameworks. By making the model publicly available, the developers foster feedback from the community, and they are committed to provide subsequent updates to ensure that the REDi Seismic Downtime Model continues to represent the state of the art in resilient design and downtime recovery modeling.

The extended SimCenter PBE Application is available for download through SimCenter’s website. To facilitate users getting started, an example problem and corresponding documentation are available in the PBE Application. Detailed documentation describing the REDi Seismic Downtime Model methodology can be found on Arup’s REDi Rating System site. To access the open-source version of the REDi Seismic Downtime Model, please visit these platforms:

Feedback is welcome from all users. To provide insights or inquiries about this development, please email the SimCenter’s Dr. Adam Zsarnóczay ( and Arup’s Dr. Stevan Gavrilovic (

We are thrilled to see these aligned efforts take shape in Arup’s open-source release of REDi and its integration as the first open-source functional recovery simulation engine in the SimCenter PBE Application. This coordination underscores SimCenter’s commitment to driving innovation, supporting open science, and bridging research and practice in the realm of engineering simulations and disaster resilience.

Adam Zsarnóczay

Associate Director for Research Outreach at SimCenter

As demand for resilient buildings and communities grows, equitable access to data and collaborative innovation are keys to ensuring that critical simulations are evolving to better meet the needs of researchers and engineers. By making the official REDi Seismic Downtime Model and previously unpublished updates open-source, we’re providing more resources to create safer and more resilient communities while championing the latest in technology and resilient design approaches.

Ibbi Almufti

Principal, Arup