This wiki page provides a list of resources within the NEEShub related to hybrid simulation (HS) and real-time hybrid simulation (RTHS) for earthquake engineering. These technologies are enabling researchers to conduct a wide array of experiments to examine the behavior of structures under realistic conditions.


Hybrid simulation (HS) is a cost-effective experimental technique to evaluate the dynamic performance of large civil structures. In hybrid simulation, a civil structure is partitioned into two substructures, (1) physical substructure, which usually includes more complex components and (2) numerical substructure, which usually includes well-studied components. And the coupling between the two substructures is achieved by enforcing equilibrium and compatibility at the interface.
Advances in embedded systems with hard real-time computing capabilities have facilitated the use of real-time hybrid simulation (RTHS) methods. Real-time hybrid simulation, which is performing hybrid simulation at real time, offers the capability of preserving rate dependence while examining the global performance (the reference structure) and local performance (the physical substructure). In RTHS, the interface interaction between the substructures is enforced by servo-hydraulic actuators or shake table which act as a transfer system. The transfer system should be designed and controlled to ensure that all the interface boundary conditions are satisfied at real time. It is known that the stability and performance of RTHS are functions of three major factors, (1) the overall dynamics of a reference system, (2) how a reference system is partitioned into numerical and physical substructures, and (3) how well the interface boundary conditions are met by a transfer system.
A typical RTHS system usually consists of the cyber and physical components,

Cyber Components
Those components that execute user programmed digital components (numerical model and actuator motion control scheme) and subsequently communicate with the sensing and analog control system through I/O modulus. Real-time kernel is included to meet the time scale constrains of RTHS.
Cyber components usually include,
• Numerical Substructure (or Computational Substructure): Numerical model of the well-studied components in the reference structure.
• Transfer System Control: Digital controller is usually included to further enhance the synchronization between computational and experimental substructures.
• Visualization and Control Dashboard: User interfaces can be included to facilitate test operation and visualize results during the tests.

Physical components
Physical components usually include,
• Physical Substructure: It includes more complex components of the reference structure and it will be constructed in the lab.
• Sensing System: In HS and RTHS, different sensors, e.g. accelerometers, LVDTs, force transducers, etc., are used to measure the restoring force of the physical substructure and monitor the performance.
• Transfer System: The interface interaction between the substructures is enforced by servo-hydraulic actuators or shake table which act as a transfer system.

= List of Resources =

== Projects ==
* [ Real-time Fast Hybrid Testing Steel Frame Test ]
* [ Semiactive Control of Nonlinear Structures ]
* [ Advanced Servo-Hydraulic Control and Real-Time Testing of Damped Structures ]
* [ Framework for Development of Hybrid Simulation in an Earthquake Impact Assessment Context ]
* [ International Hybrid Simulation of Tomorrow's Braced Frame Systems. ]
* [ Development of a Real-Time Multi-Site Hybrid Testing Tool for NEES ]
* [ Development and Validation of a Robust Framework for Real-time Hybrid Testing ]
* [ Real-Time Hybrid Simulation Test-Bed for Structural Systems with Smart Dampers ]

== Tools ==
* [ NHCP ]
* [ OpenFresco ]
* [ UI-SimCor ]
* [ RT-Frame2D ]

== Publications ==
* [ Real-time Hybrid Simulation Benchmark Study with a Large-Scale MR Damper ]
* [ Comparison of 200 KN MR Damper Models for use in Real-time Hybrid Simulation ]
* [ Evaluation of Structural Control Strategies for Improving Seismic Performance of Buildings with MR Dampers Using Real-Time Large-Scale Hybrid Simulation ]
* [ A Tracking Error-Based Adaptive Compensation Scheme for Real- Time Hybrid Simulation ]
* [ Servo-Hydraulic Actuator Control for Real-Time Hybrid Simulation ]
* [ Accommodating MR Damper Dynamics for Control of Large Scale Structural Systems ]
* [ Real-Time Hybrid Testing of an MR Damper for Response-Reduction (Dissertation) ]
* [ Hybrid Simulation Evaluation of Innovative Steel Braced Framing System ]
* [ Increasing Resilience in Civil Structures Using Smart Damping Technology (Dissertation)]
* [ Evaluating Modeling Choices in the Implementation of Real-time Hybrid Simulation ]
* [ Final Report: Evaluation of a real-time hybrid simulation system for performance evaluation of structures with rate dependent devices subjected to seismic loading ]
* [ Model-Based Framework for Real-Time Dynamic Structural Performance Evaluation ]
* [ Development of a Robust Framework for Real-Time Hybrid Simulation: from Dynamical System, Motion Control to Experimental Error Verification (Dissertation)]
* [ Development and validation of a real-time computational framework for hybrid simulation of dynamically-excited steel frame structures (Dissertation)]

== Reports ==
* [ NEES Vision Report on Computational and Hybrid Simulation (Committee Report) ]
* [ Advanced Servo-Hydraulic Control And Real-Time Testing Of Damped Structures ]
* [ Semiactive Control of Nonlinear Structures ]
* [ Development and Validation of a Robust Actuator Motion Controller for Real-time Hybrid Simulation Applications ]
* [ Development and Validation of a Computational Tool for Real-time Hybrid of Steel Frame Structures ]
* [ Hybrid Testing in NEESR Projects ]

== Workshops ==
* [ CU/NEES Fast Hybrid Testing Workshop ]
* [ Hybrid Simulation Workshop at NEES@Berkeley ]
* [ Advances in Real-Time Hybrid Simulation Workshop at NEES@Lehigh ]
* [ Hybrid Simulation Workshop @ Harbin Institute of Technology ]

== Multimedia ==
* [ NEES@Berkeley project highlight: NEES TIPS Seismic Isolation Hybrid Simulation ]
* [ NEES@Berkeley project highlight: International Hybrid Simulation of Tomorrow's Braced Frame ]
* [ NEES@Berkeley project highlight: Hybrid Testing of Squat RC Shear Walls ]