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Hybrid Simulation and Real-time Hybrid Simulation Resources in the NEEShub

This wiki 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 loading conditions.

HYBRID SIMULATION (HS): Hybrid simulation is a cost-effective experimental technique to evaluate the dynamic performance of large or full scale civil structures. In hybrid simulation, the rate-dependent behavior of a civil structure, including inertial and damping effects, is simulated numerically while the displacement-dependent behavior is evaluated through experimentation. Furthermore, through the technique of substructuring, a structure (total or reference structure) can be partitioned into, (1) a physical (or experimental) substructure, which usually includes the more complex components and (2) a numerical (or computational, analytical) substructure, which usually includes well-understood behavior that can be captured by numerical models. The coupling between the two substructures is achieved by enforcing equilibrium and compatibility at the interface using a transfer system such as servo-hydraulic actuators.

REAL-TIME HYBRID SIMULATION (RTHS): Advances in embedded systems with hard real-time computing capabilities have facilitated the use of real-time hybrid simulation methods. Compared to HS, RTHS offers the capability of accurately representing the rate-dependent behavior of the physical components 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 a shake table which act as the transfer system. A transfer system must be controlled to ensure that all interface boundary conditions are satisfied in real time. Performance of RTHS are functions of four major factors (1) the overall dynamics of the total structure (2) the accuracy of the numerical substructure (3) how the total structure is partitioned into numerical and physical substructures (4) how well the interface boundary conditions are achieved by the transfer system.


A typical RTHS system consists of cyber and physical components.

A. Cyber Components: These components execute user programmed digital functions (numerical model and transfer system motion control scheme) and while communicating with the physical world through I/O and analog sensing and actuation systems. A real-time kernel is included to meet the time scale constraints of RTHS. Cyber components include,

• Numerical Substructure: Portion of the total structure included in the numerical model. • Transfer System Control: Digital controller is included to enable synchronization between numerical and physical substructures.

• Visualization and Control Dashboard: User interfaces and data logging components facilitate operation and visualization results during a hybrid experiment.

B. Physical components: This term refers to the portions of the reference structure that are present in the laboratory, as well as the sensors and transfer system that are used for performing the experiment. In RTHS, measured responses are fed back to the cyber components in real time. Physical components include,

• Physical Substructure: Portion of the reference structure included in the physical specimen.

• Sensing System: In RTHS, sensors, e.g. accelerometers, LVDTs, force transducers, etc., are used to measure the restoring force and local response for transfer system control feedback of the physical substructure and monitor the performance.

• Actuation System: The interface interaction between the substructures is enforced by servo-hydraulic actuators or a shake table which acts as a transfer system.

List of Resources







Created on , Last modified on