Hybrid Simulation Tests Research Articles

Hybrid Simulation Testbed for Experimental Validation and Characterization of NDE and Sensor Technology

An increasing number of online structural health monitoring systems have been implemented on bridges, which are often comprised of a variety of local sensing and nondestructive evaluation (NDE) devices. However, before any new type of sensor and NDE technology, such as ultrasonic surface wave sensors, can be deployed for field implementation, they first need to be validated and characterized under realistic loads and environmental conditions in a controlled laboratory setting. This paper demonstrates the use of a hybrid testing setup to create a characterization testbed for more realistic evaluation of NDE and sensor technologies. A prototype bridge structure based on the Yellow Mill Pond Bridge in Connecticut was selected to demonstrate the features and issues of a hybrid simulation testbed for sensor characterization, such as flexibility in traffic load representation, and large-scale specimens even with small testing equipment. Using this prototype bridge structure, a series of hybrid simulation tests using real variable-amplitude traffic loading were performed on a 0.6-scale steel flange plate specimen with a welded cover plate. Features of this hybrid simulation testbed are discussed, including the complexity of the virtual model (e.g., the dynamic mass effects and damping of the structure) and stability issues that can develop in the test. Finally, the ability of the hybrid testing platform to evaluate sensor performance under varying environmental conditions was demonstrated for elevated temperatures. Although a strain gauge was used to demonstrate the technology, the sensor testbed can be used for general characterization of other types of NDE devices and sensors.

Integrated Analytical and Experimental Research to Develop a New Seismic Design Methodology for Precast Concrete Diaphragms

AbstractA new seismic diaphragm design methodology has been developed for precast concrete floor diaphragms. The knowledge required to create the design methodology was obtained through an integrated analytical and experimental research project using two Network for Earthquake Engineering Simulation (NEES) equipment sites. The activities of the project involved a sequence of integrated research tasks that systematically developed knowledge about diaphragm behavior from the reinforcement detail level to the structural system level. These tasks included the use of state-of-the-art experimental techniques made possible through the NEES facilities including hybrid simulation and large-scale shake table tests. Such techniques were crucial to the research as the complex behavior of precast diaphragms is not well described by simple analytical models or idealized experiments. Valuable industry oversight in the planning, execution, and technology transfer stages of the project guided the research activities, incl...

Tall building vibration control using a TM‐MR damper assembly: Experimental results and implementation

AbstractThis paper summarizes the relevant results of the design, construction, testing, and implementation of a nominal 120 kN magnetorheological damper developed to control a free‐plan tall building in Santiago, Chile, equipped with two 160‐ton tuned masses. Cyclic as well as hybrid simulation tests were performed on the prototype damper. Global building responses using measured MR properties showed good correlation with analytical estimations. Also, a proposed physical controller for the MR damper was validated through hybrid and building pull‐back tests. Its performance is essentially equivalent to that of an LQR controller, but the information needed in its implementation is considerably less. Pull‐back tests of 10 cm amplitude were performed on one mass along the flexible edge of the building and its response controlled using the passive and controlled modes of the MR damper. The MR damper was capable of controlling the TM displacements very effectively, as well as the simulated building response for different ground motions and harmonic excitation. Copyright © 2010 John Wiley & Sons, Ltd.

Guided construction of testing scenarios for autonomous underwater vehicles using the augmented-reality framework and JavaBeans

System evaluation and testing of unmanned underwater vehicles in their destined environment can be tedious, error prone, time consuming, and consequently expensive. However, pre-real-world testing facilities, such as hardware-in-the-loop (HIL) testing, are not always available. This is due to the time and expense required to create a specific test environment for the vehicle. Thus the system is not as fault tolerant as it could be since problems can remain undetected until the real-world testing phase. Debugging and fixing errors in the real-world testing phase are much more time consuming and expensive owing to the nature of the harsh underwater environment. This paper introduces a novel framework, the augmented-reality framework (ARF), for the rapid construction of virtual-environment testing scenarios for testing remote platforms with embedded systems such as autonomous underwater vehicles. The ARF provides testing facilities across all stages of the reality continuum, providing capabilities for pure simulation, HIL, hybrid simulation, and real-world testing. The framework architecture is both very generic and flexible and allows mixing of real and simulated components. The ARF is supported by a distributed communications protocol which provides location transparency of systems since this is key to providing mixed-reality testing facilities.

Hybrid simulation of a zipper‐braced steel frame under earthquake excitation

AbstractHybrid simulation is a testing methodology that combines laboratory and analytical simulation to evaluate seismic response of complex structural framing systems. One or more portions of the structure, which may be difficult to model numerically or have properties that have not been examined before, are tested in one or more laboratories, whereas the remainder of the structure is modeled in software using one or more computers. These separate portions are assembled such that combined dynamic response of the hybrid model to excitation is computed using a time‐stepping procedure.A hybrid simulation conducted to examine the seismic response of a type of steel concentrically braced frame, the suspended‐zipper‐braced frame, is presented. The hybrid simulation testing architecture, hybrid model, test setup, solution algorithm, and the seismic response of the suspended‐zipper‐braced frame hybrid model are discussed. Accuracy of this hybrid simulation is examined by comparing hybrid and computer‐only simulations and the errors are quantified using an energy‐based approach. This comparison indicates that the deployed hybrid simulation method can be used to accurately model the seismic response of a complex structural system such as the zipper‐braced frame. Copyright © 2008 John Wiley & Sons, Ltd.

Hybrid Seismic Response Simulation on a Geographically Distributed Bridge Model

The hybrid simulation test method is a versatile technique for evaluating the seismic performance of structures by seamlessly integrating both physical and numerical simulations of substructures into a single test model. Using hybrid simulation, the seismic response of complex structural systems partitioned into multiple large-scale experimental and numerical substructures at networked geographically distributed experimental and computational facilities can be evaluated. A scalable framework with a fault-tolerant distributed controller is presented to support the implementation of advanced hybrid testing methods with distributed substructures. The control strategy is based on a multithreaded simulation coordinator for parallel communication with remote sites and an event-driven controller at each remote experimental site to implement continuous loading. The distributed controller provides faster rates of testing and improved accuracy in the simulation results. The effectiveness of the proposed framework is demonstrated by computing the earthquake response of a six-span bridge model with multiple remote experimental and numerical column substructures distributed within NEES laboratories across the United States. Further, the distributed tests were implemented using a secure network link between the testing sites that was developed for the NEES cyber infrastructure.

Real-Time Error Monitoring for Hybrid Simulation. Part I: Methodology and Experimental Verification

The hybrid simulation test method is a versatile technique for evaluating the seismic performance of structures by seamlessly integrating both physical and numerical simulations of substructures into a single test model. Hybrid simulation results have been shown to be reliable by comparison to shake-table simulations when propagation of experimental errors is successfully mitigated. Techniques have been proposed to assess the severity of experimental errors prior to or after tests have been completed. In this paper, an error monitoring method is presented that predicts the reliability of the test results in real time using data that is readily available. Two error monitors are derived based on estimates of energy added to the hybrid simulation as a result of errors in the experimental setup. The proposed method can provide valuable decision-making information by generating early warnings of unacceptable levels of experimental errors. The warning signals can serve as an indicator to pause the simulation, examine the source of error, and correct the problem, preferably before the specimen is irreparably damaged. Use of the proposed hybrid simulation error monitors to provide a measure of confidence of the quality of the test results is verified in two hybrid simulations.

A Study on Dynamic Behaviour of Pantographs by Using Hybrid Simulation Method

To study the dynamic behaviour of pantographs, a hybrid simulation method has been used. A special test facility, which is used to simulate the dynamic performance of a pantograph when it runs through the overhead line, is established and described in this paper. As the catenary is difficult to be modelled by a hardware test facility indoor, a mixed theoretical-experimental technique is used in test facility. On the basis of the set-up of hybrid simulation test device of the pantograph-catenary system, the dynamic behaviours of four types of pantographs running along the overhead equipment at different running speeds are examined and compared. Meanwhile, the dynamic parameters such as mass, stiffness, and damping of four pantographs are measured using the hybrid simulation test facility. On the basis of these parameters, the dynamic behaviours of the four pantographs are analysed.