Real-ESSI Simulator

Education and Training
Modeling Approach
Modeling and Simulation Features


The Real-ESSI Simulator ( Realistic Modeling and Simulation of Earthquakes, and/or Soils, and/or Structures and their Interaction) is a software, hardware and documentation system for high performance, sequential or parallel, time domain, linear or nonlinear, elastic and inelastic, deterministic or probabilistic, finite element modeling and simulation of

The Real-ESSI Simulator systems is used for (a) design and for (b) assessment of static and dynamic behavior of infrastructure objects, including buildings, bridges, dams, nuclear installations, tunnels, etc.

Design: Multiple linear elastic load cases can be combined and design quantities, sectional forces exported for design.

Assessment: Practical, realistic, inelastic, nonlinear load staged analysis, with accurate modeling of elastic and inelastic, nonlinear components, and with all the necessary simulation/algorithmic features available, as listed below, is performed to assess design, safety margins and economy of infrastructure objects.

The Real-ESSI Simulator is developed at the University of California, Davis, in collaboration and with partial financial support from the US-DOE, US-NRC, US-NSF, US-BR, US-FEMA, CalTrans, CNSC-CCSN, CH-ENSI/B&H AG, UN-IAEA, Shimizu Corp., etc.

The Real-ESSI Simulator develops methods and models that inform and predict.

Brief history of the Real-ESSI Development.

Real-ESSI Simulator Education and Training

Real-ESSI Simulator System Availability

Real-ESSI Simulator Version

Current Real-ESSI Simulator release version is: Global Release, 23.01, Jan2023.

Next Real-ESSI Simulator release version will be: Global Release, 23.07, Jul2023.

Past Real-ESSI Simulator release version was: Global Release, 22.07, Jul2022.

Change LOGS, for the GLOBAL_RELEASE, that is, what have we added, improved and changed in last year or so...

Real-ESSI Simulator system documentation

To view Real ESSI Simulator system documentation PDFs it is best to use Google Chrome. All the libe links, animations, etc. work well within Google Chrome. Simpler, portable versions of PDFs is also provided, however links and animations do not work.

Complete documentation, including all of the previous documents and manuals is available within Lecture Notes:
Nonlinear Finite Elements: Modeling and Simulation of Earthquakes, Soils, Structures and their Interaction

Real-ESSI Simulator Modeling Approach

Practical, variable fidelity (low to high) modeling and simulation is performed in order to control and reduce modeling, epistemic uncertainty. Modeling uncertainty is introduced in models, and subsequent simulation results, when modeling simplifications, some unnecessary and some unrealistic, are made.

While the Real-ESSI Simulator is capable of analyzing high fidelity, high sophistication models, simplified models are also possible to analyze. In fact, the Real-ESSI Simulator allows modeling of a full hierarchy of models, from simplest models to very sophisticated models. Modeling and simulation from simple to more sophisticated models is encouraged, in order to gain better understanding of model behavior and to gain confidence in analysis results.

For example, a building model can start as a simple stick or a simple frame on a fixed base. Next, analyst can add wall, plate and shell elements, and later springs for foundation modeling, all linear elastic. Next, analyst might add solids and more realistic foundation model, all still linear elastic. Loading can start with simple static pushovers, simple dynamic pushes at certain locations. Next, analyst might change material models for parts of the soil-structure system from linear elastic to nonlinear, inelastic. Similar simple loads are applied, to test the model. Along the way of these changes, while climbing up the hierarchy of model sophistication, analyst will be able to gain good understanding of model behavior, and sensitivity of model response to various simplified or sophisticated modeling options, various material behavior, various loads, etc. Finally, analyst might use a sophisticated, realistic model, with realistic loading, using many available Real-ESSI Simulator modeling and simulation features.

It is highly recommended to follow this hierarchy of modeling from simpler toward more sophisticated models, particularly for nonlinear analysis. It is also highly recommended to use sound engineering judgement in inspecting and understanding simulation results. It can happen, and it does happen, that instant use of very sophisticated models, without model verification and gradual understanding of model behavior through hierarchy of models, lead to results that are difficult to understand and that can sometimes be wrong due to use of wrong modeling details. Presence of potential errors in results can also be due to the modeling approximations and simplifications. Influence of those approximations and simplifications needs to be understood, using hierarchy of models, before simulation results can be used for design and assessment.

Real-ESSI Simulator Modeling and Simulation Features

For additional information, please contact Boris Jeremić ( jeremic @ ucdavis . edu ), use Subject: Real-ESSI.

Web page version: 01Feb2023