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Grid service technologies are often used to increase computational capacity. However, they may also be used to connect and share physical resources in a coordinated manner. This technology is showing potential applications in earthquake engineering where structural seismic response, measured by testing, is used to understand structural failures and...
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... Distributed hybrid tests have also since been conducted within the United States of America (USA) [119], UK [126] and Taiwan [127] and between a number of countries, ...
An overview of research on the development of the hybrid test method is presented. The maturity of the hybrid test method is mapped in order to provide context to individual research in the overall development of the test method. In the pseudo dynamic (PsD) test method, the equations of motion are solved using a time stepping numerical integration technique with the inertia and damping being numerically modelled whilst restoring force is physically measured over an extended timescale. Developments in continuous PsD testing led to the real-time hybrid test method and geographically distributed hybrid tests. A key aspect to the efficiency of hybrid testing is the substructuring technique where the critical structural subassemblies that are fundamental to the overall response of the structure are physically tested whilst the remainder of the structure whose response can be more easily predicted is numerically modelled. Much of the early research focused on developing the accuracy and efficiency of the test method, whereas more recently the method has matured to a level where the test method is applied purely as a dynamic testing technique. Developments in numerical integration methods, substructuring, experimental error reduction, delay compensation and speed of testing have led to a test method now in use as full-scale real-time dynamic testing method that is reliable, accurate, efficient and cost effective.
... The first implementation of a geographically distributed hybrid test was performed between Kyoto University and Osaka City University, Japan ). Since then, geographically distributed hybrid tests have been conducted internally within the United States (Spencer et al. (2004)), United Kingdom (Saleem et al. (2008)) and Taiwan (Yang et al. (2003)) and between a number of countries, notably Korea/Japan ), the United States/Japan (Park et al. (2005)), the United States/Taiwan Wang et al. (2007)) and New Zealand/United States (Ma et al. (2007)). A number of distributed hybrid test frameworks have been developed over the past 15 years to improve the communication between the physical and numerical substructure locations. ...
Even though computational power used for structural analysis is ever increasing, there is still a fundamental need for testing in structural engineering, either for validation of complex numerical models or material behaviour. Many structural engineers/researchers are aware of cyclic and shake table test methods, but less so hybrid testing. Over the past 40 years, hybrid testing of engineering structures has developed from concept through to maturity to become a reliable and accurate dynamic testing technique. In particular, the application of hybrid testing as a seismic testing technique in recent years has increased notably. The hybrid test method provides users with some additional benefits that standard dynamic testing methods do not, and the method is much more cost effective in comparison to shake table testing. This paper aims to provide the reader with a basic understanding of the hybrid test method and its potential as a dynamic testing technique.
... A current trend in hybrid testing aims to provide a network for collaborative research within an integrated experimental and computational framework. Such networks exist in the US through Network for Earthquake Engineering Simulation (NEES) [14] and the United Kingdom through United Kingdom Network for Earthquake Engineering Simulation (UK-NEES) [15]. Subsequently, in the United States there has been a drive towards a generic hybrid simulation framework that will allow testing to be undertaken at different laboratories, with different test equipment without specialised knowledge required for the underlying software. ...
The hybrid test method is a relatively recently developed dynamic testing technique that uses numerical modelling combined with simultaneous physical testing. The concept of substructuring allows the critical or highly nonlinear part of the structure that is difficult to numerically model with accuracy to be physically tested whilst the remainder of the structure, that has a more predictable response, is numerically modelled. In this paper, a substructured soft-real time hybrid test is evaluated as an accurate means of performing seismic tests of complex structures. The structure analysed is a three-storey, two-by-one bay concentrically braced frame (CBF) steel structure subjected to seismic excitation. A ground storey braced frame substructure whose response is critical to the overall response of the structure is tested, whilst the remainder of the structure is numerically modelled. OpenSees is used for numerical modelling and OpenFresco is used for the communication between the test equipment and numerical model. A novel approach using OpenFresco to define the complex numerical substructure of an X-braced frame within a hybrid test is also presented. The results of the hybrid tests are compared to purely numerical models using OpenSees and a simulated test using a combination of OpenSees and OpenFresco. The comparative results indicate that the test method provides an accurate and cost effective procedure for performing full scale seismic tests of complex structural systems.
A distributed remote collaborative hybrid test (RCHT) method for complex substructures based on OpenFresco is presented in this paper. Challenges in the RCHT include the modeling of the numerical substructure, boundary degree-of-freedom (DOF) loading, and equivalent communication of the multi-story space frame as a test substructure in OpenFresco. The effectiveness and accuracy of the proposed RCHT method are verified by a series of remote distributed tests that reproduce the seismic response of a three-story five-span space Y-shaped eccentric brace steel frame model consisting of two test substructures and a numerical substructure. The main contributions of this study are the realization of the multi DOF loading RCHT of the space global frame and reasonable simplification of the substructure boundaries, which further promotes the use of the RCHT method to realize the seismic performance simulation of complex substructures.
A distributed remote collaborative hybrid test (RCHT) method for complex substructures based on OpenFresco is presented in this paper. Challenges in the RCHT include the modeling of the numerical substructure, boundary degree-of-freedom (DOF) loading, and equivalent communication of the multi-story space frame as a test substructure in OpenFresco. The effectiveness and accuracy of the proposed RCHT method are verified by a series of remote distributed tests that reproduce the seismic response of a three-story five-span space Y-shaped eccentric brace steel frame model consisting of two test substructures and a numerical substructure. The main contributions of this study are the realization of the multi DOF loading RCHT of the space global frame and reasonable simplification of the substructure boundaries, which further promotes the use of the RCHT method to realize the seismic performance simulation of complex substructures.
Distributed Hybrid Testing (DHT) is an experimental technique designed to capitalise on advances in modern networking infrastructure to overcome traditional laboratory capacity limitations. By coupling the heterogeneous test apparatus and computational resources of geographically distributed laboratories, DHT provides the means to take on complex, multi-disciplinary challenges with new forms of communication and collaboration. To introduce the opportunity and practicability afforded by DHT, here an exemplar multi-site test is addressed in which a dedicated fibre network and suite of custom software is used to connect the geotechnical centrifuge at the University of Cambridge with a variety of structural dynamics loading apparatus at the University of Oxford and the University of Bristol. While centrifuge time-scaling prevents real-time rates of loading in this test, such experiments may be used to gain valuable insights into physical phenomena, test procedure and accuracy. These and other related experiments have led to the development of the real-time DHT technique and the creation of a flexible framework that aims to facilitate future distributed tests within the UK and beyond. As a further example, a real-time DHT experiment between structural labs using this framework for testing across the Internet is also presented.
Technological developments in dynamic testing have made use of computational power and advances in hardware to provide more cost-effective methods of full-scale dynamic testing as compared to shake-table testing. The actuators have been more efficiently employed in hybrid testing rather than using multiple hydraulic actuators to push a shake table. This method combines physical testing with simultaneous computational modeling. It has been widely implemented in earthquake structural engineering testing and is discussed in general terms. Physical testing remains an important part of the progression of engineering science and the hybrid test method has advanced with developing computational power to achieve a cost-effective full-scale dynamic testing method.
SUMMARY Large-scale testing and qualification of structural systems and their components is crucial for the development of earthquake engineering knowledge and practice. However, laboratory capacity is often limited when attempting larger experiments due to the sheer size of the structures involved. To overcome traditional laboratory capacity limitations, we present a new earthquake engineering testing method: real-time distributed hybrid testing. Extending current approaches, the technique enables geographically distributed scientific equipment including controllers, dynamic actuators and sensors to be coupled across the Internet in real-time. As a result, hybrid structural emulations consisting of physical and numerical substructures need no longer be limited to a single laboratory. Larger experiments may distribute substructures across laboratories located in different cities whilst maintaining correct dynamic coupling, required to accurately capture physical rate effects. The various aspects of the distributed testing environment have been considered. In particular, to ensure accurate control across an environment not designed for real-time testing, new higher level control protocols are introduced acting over an optimised communication system. New large time-step prediction algorithms are used, capable of overcoming both local actuation and distributed system delays. An overview of the architecture and algorithms developed is presented together with results demonstrating a number of current capabilities. Copyright © 2013 John Wiley & Sons, Ltd.
