Real-ESSI / MS-ESSI Simulator


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

The Real-ESSI Simulator systems is used for design and for 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 load staged analysis, with all the inelastic components properly modeled, and with all the simulation, algorithmic features available, as listed below, is performed to assess design and current safety and economy of objects.

The Real-ESSI / MS-ESSI Simulator was developed in collaboration and with partial financial support from the US-DOE, US-NRC, US-NSF, Caltrans, CNSC-CCSN, UN-IAEA, Shimizu, etc.

The Real-ESSI / MS-ESSI Simulator develops methods and models that inform and predict rather than (force) fit.



Real-ESSI / MS-ESSI Simulator system is available for use on Amazon Web Services computers, search for "Real ESSI" or "MS ESSI".


Lecture Notes available for download:
Nonlinear Finite Elements: Modeling and Simulation of Earthquakes, Soils, Structures and their Interaction




Real-ESSI / MS-ESSI Simulator current release version: Global Release, Dec2018, 18.12.

Immediate past Real-ESSI / MS-ESSI Simulator release version: Global Release, Jun2018, 18.06.


Illustrations of Real-ESSI / MS-ESSI Simulator Capabilities:

Seismic response of a Nuclear Power Plant, 3D vs 1D motions: 1D vs 3D seismic motions.

Real-ESSI / MS-ESSI Simulator system documentation:


Real-ESSI / MS-ESSI Simulator Modeling Approach:

Practical, high fidelity modeling and simulation is performed in order to reduce modeling uncertainty. Modeling uncertainty is introduced in models, and subsequent simulation results, when unrealistic and sometimes unnecessary modeling simplifications are made.

While the Real-ESSI / MS-ESSI Simulator is capable of analyzing high fidelity, high sophistication models, simplified models are also possible to analyze. In fact, the Real-ESSI / MS-ESSI Simulator allows modeling of a full hierarchy of models, from simplest models to the very sophisticated models.

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 perhaps springs to foundation model, all linear elastic. Next, analyst might add solids and more realistic foundation model, all still linear elastic. Next, analyst might start to change material models for parts of the soil-structure system from linear elastic to nonlinear, inelastic. Along the way of these changes and climb up the hierarchy of model sophistication, analyst will be able to gain good understanding of model behavior, sensitivity of model response to various modeling options (simplified or sophisticated). Finally, analyst might use a very sophisticated model, using available Real-ESSI / MS-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 be wrong. Presence of potential errors in results can be due to the modeling approximations. Influence of those approximations need to be understood, using hierarchy of models, before simulation results can be used for design and assessment.


Real-ESSI / MS-ESSI Simulator Modeling and Simulation Features:


Real-ESSI / MS-ESSI Simulator System Availability:


For additional information, please contact Boris Jeremić (jeremic @ ucdavis.edu or bjeremic @ lbl.gov).


version: December 2018