Large-scale Test Facilities Research Articles

Development Of An Endoscopic, Absorption Corrected And Calibrated OH Laser Induced Fluorescence Probe System for High Pressure Combustion Diagnostics

We present the design and preliminary results of an endoscopic OH laser-induced fluorescence (LIF) system that is capable of acquiring 1D-line measurements in high pressure combustion processes within large-scale test facilities. The system can be exploited to acquire line-of-sight OH-chemiluminescence images and absorption corrected absolute OH-species concentration from which additionally temperature distribution can be extracted in case of lean mixtures in chemical equilibrium. Different critical components, such as light guides for high power UV laser pulses and flexible UV image guides, were first tested and characterized in a laboratory setup. Optimization regarding pulse energy and beam quality led to the selection of an 1m long hollow core fiber for laser light delivery as a central element for the experimental setup despite high losses caused by bending the fiber. The image transfer is accomplished by a 7m long flexible UV image bundle, which is preferred to the use of a rigid borescope in harsh environments. We designed the endoscopic UV optics using readily available parts and achieved an approximated image resolution of 21.6 line pairs/mm. Additionally, post-processing methods, such as flat-field correction, can improve the image quality substantially and remove the pixilation effect of the fiber bundle structure nearly completely. To validate the complete system, probe-based qualitative OH-LIF measurements were performed in a well-known laminar flame of a matrix burner, which serves as a mock-up for anticipated applications in an industrial test environment with a technology readiness level (TRL) greater than 4. The final step consists of the integration of the miniaturized optics into a cooled probe system which protects the sensitive optics against the harsh environment of an aero-engine sector combustor. For this purpose, two probe systems were designed to include, on the one hand, the endoscope optics together with the fiber image bundle end tip and, on the other hand, the laser emitting and receiving system for performing an absorption measurement needed to quantify the recorded LIF signal.

Undrained shear strength estimation through instrumented free-fall penetration tests using spherical and conical penetrometers

This paper presents (i) results from a series of instrumented free-fall penetration (FFP) tests performed, under laboratory-controlled conditions, in a large-scale testing facility and (ii) a simple methodology to predict undrained shear strength su from FFP test data without resorting to assumptions on the values of different parameters. Comparison of soil resistance derived from acceleration data recorded during FFP tests with soil resistance recorded during constant rate penetration (CRP) tests using a ball penetrometer reveals unique relationships between dynamic and constant-rate penetration resistances for different shapes of FFP tools. Based on regression analysis, expressions are proposed for calculation of resistance ratio ξr for three different shapes of FFP tool. The proposed expressions for ξr further facilitate the prediction of undrained shear strength su employing acceleration data recorded during FFP tests. FFP-based predictions of su show excellent agreement with CRP-based su prediction in three different laboratory testbeds. Furthermore, the proposed methodology successfully predicts su profile at a field test site using FFP test data reported in the literature.

Digitalization of Large-Scale Testing Facilities for the Wind Industry: DIGIT-BENCH Digital Twin

Testing of large wind turbine components plays a central role in delivering reliable yet cost-effective technology. However, these experiments are often lengthy and costly. Fatigue testing of a wind turbine blade might take up to 12-14 months, whereas highly accelerated lifetime testing of a nacelle demands 6-8 months. The exchange of simulation models and data between OEMs and test facilities is recognized as a critical factor in the planning of an experimental campaign. In fact, OEMs are typically very protective of their industrial secrets, and sharing such sensitive information may constitute a threat. It follows that the use of simulation models to enable more effective experimentation is not pursued efficiently.Digital twins are emerging as a key enabling technology to improve the operation & maintenance of test benches for the wind industry. A digital twin combines physical systems and their digital models into a cyber-physical system to provide functionalities that cannot be attained by either physical or digital assets independently. The seamless integration of the test bench with digital models offered by a digital twin is expected to enhance the interaction between OEM and test bench operators.This proceeding illustrates the status of the development of the DIGIT-BENCH digital twin developed by R&D Test Systems (R&D) and Aarhus University to serve large-scale test facilities for the wind industry. The digital twin utilizes FMI-based co-simulation to enable the coupling of physical/digital components in an industrial-secret-friendly environment. The digital twin concept is demonstrated on a 2-degrees-of-freedom test bench installed at Aarhus University.

Experimental investigation of shear-extension coupling effect in anisotropic reinforced concrete membrane elements

Performance based analysis under seismic loads using the finite element method for wall-type reinforced concrete (RC) members in buildings and in important structures like liquid retaining structures, nuclear containment structures, offshore concrete gravity structures etc., necessitates the understanding of the non-linear behaviour of the constituent membrane elements. The current orthotropic formulation of the softened membrane model (SMM) can be strictly used only when the reinforcement is symmetric to the principal axes of applied stresses. When the reinforcement is asymmetric, shear strain is generated due to the normal stresses in the principal axes of applied stresses, which is referred to as shear-extension coupling. An anisotropic formulation is required to capture the generated shear strain. The current study quantifies the shear strain due to asymmetry in reinforcement, by testing panels under biaxial tension-compression using a large-scale panel testing facility. A model for the shear strain is proposed based on the tests data. The paper presents the experimental programme, important test results and the modelling of shear strain. Expression developed for the shear strain can be incorporated in the solution algorithm of the SMM for improved prediction of the shear behaviour of a membrane element. This further aids in accurate prediction of the seismic performance of the important structures mentioned earlier.

Annular Dump Diffuser and Deswirl System for Back-Pressure Control in Engine-Scale Transonic Annular Cascade

Abstract A common requirement for turbomachinery testing facilities is the ability to independently control Mach number and Reynolds number. In practice, this means independent control of the inlet total pressure and exit static pressure in a test facility. In this paper, we present a solution to this problem with particular applicability to large-scale annular test facilities. We describe the design and commissioning of a combined annular dump diffuser and deswirl system for back-pressure control in environments with high-whirl transonic flow. The particular application was an annular cascade of nozzle guide vanes from a current civil engine. The purpose was to provide independent control of Mach number and Reynolds number, by controlling the back-pressure in the intermediate annular plenum which forms the dump diffuser. The dump diffuser is necessary to facilitate optical and probe access (without interaction effects) and to reduce the risk of exit static pressure disturbances (due to particular duct design). The system has been installed and validated in the engine component aerothermal (ECAT) facility at the University of Oxford. In this implementation of the system, the high-whirl transonic flow from the nozzle guide vanes passes through a short, parallel annular duct, and is dumped into an annular plenum, before being re-accelerated into a deswirl vane ring. The deswirl ring turns the flow to the axial direction. The flow is then discharged through a variable choke plate into a silencer. Conditioning the flow to have zero whirl at the choke plate reduces the sensitivity of the choke plate effective blockage to the whirl angle. The design, deswirl vane aerodynamic performance, and overall system performance are assessed with detailed experiments and 3D unsteady computational fluid dynamics predictions. The control of high-whirl transonic flow is notoriously challenging, and the deswirl system has application to exhaust conditioning in a number of applications including annular cascade experiments and rocket turbo-pump exhaust systems.

Hydrogen recombination scaling experiments at CNL’s hydrogen safety test facility

After many years of passive autocatalytic recombiner (PAR) experimentation and analytical investigations, there are still gaps in the understanding of PAR behavior. For instance, PAR performance under severe accident conditions including issues related to low oxygen content, presence of carbon monoxide, and reactive or non-reactive aerosols still require examination.Following the closure of the large-scale hydrogen test facilities at AECL’s Whiteshell Laboratories (WL), a new Hydrogen Safety Test Facility (HSTF) has been commissioned at Chalk River Laboratories (CRL) to continue the efforts to understand PARs and their operation in various accident scenarios. The HSTF is a spherical pressure vessel with an internal volume of 0.25 m3. This paper presents the experiments performed at the HSTF, investigating the scaling of a PAR under varying concentrations of H2, and steam as well as the effects of initial gas temperature and pressure. The experimental data from the HSTF (0.25 m3) will be compared with the data obtained in the large-scale facilities (6.6 m3 and 60 m3) to establish a scaling factor for the HSTF with a reasonable fit over the range of conditions tested.

Large-scale testing facility for heavy haul track

Given the substantially increased demand for increased axle loads of heavy haul trains, there is an imperative need to develop sustainable track infrastructure. When subjected to heavy axle loading, ballast aggregates rapidly break down, compromising the particle friction and associated load bearing capacity. Therefore, understanding the deformation and degradation (breakage) of ballast subjected to various boundary and loading conditions is crucial for improved track design and performance monitoring. Ideally, field testing should be carried out in real-life tracks to avoid laboratory scale and boundary effects, but field tests are often expensive, time-consuming and may disrupt rail traffic, hence not always feasible. A prototype test facility that can simulate appropriate axle loading and boundary conditions for standard gauge heavy haul tracks is presented in this paper. In collaboration with more than a dozen Universities and Industry organisations, Australia's first and only National Facility for Heavy-haul Railroad Testing (NFHRT) has recently been constructed and is now fully operational. This new facility enables a real-size (1:1 scale) instrumented track section to be subjected to continuous cyclic loading simulated via two pairs of dynamic actuators in synchronized operation. The results of a typical test are presented in this paper including the measured track settlement and lateral deformation, transient vertical and lateral stresses, rail and sleeper accelerations, resilient modulus and breakage of ballast. The test results show that an average track settlement of about 14 mm and lateral displacements up to 9 mm are recorded after 500,000 load cycles. Subjected to a 25-tonne axle load, the maximum vertical stress measured at the sleeper-ballast interface is about 225 kPa and this attenuates with depth. The test results of this iconic facility are generally consistent with actual field measurements obtained in heavy-haul tracks located in the towns of Singleton and Bulli in the state of New South Wales, Australia.

Large-scale testing and finite-element simulation of twin square anchor plates embedded at shallow depth in layered soil media

The motivation and scope of the present work are to investigate the interaction phenomenon of two closely spaced square plate anchors through physical modelling and validating it with the help of finite-element modelling. In the present study, different sizes of plate anchors are considered for studying their uplift behaviour when they are laid as single as well as in a group of two symmetrical anchors. A large-scale model testing facility has been developed and fabricated in order to perform the physical modelling. In physical modelling, poorly graded, dry Quartzanium sand is utilized as the foundation material. PLAXIS3D, a finite-element software for geotechnical engineering, has been used to validate the experimental results obtained from the large-scale model testing facility. The effects of embedment depth and size of the anchor plate as well as layering in soil media are the parameters considered in order to determine the interaction factors with respect to the uplift capacity and displacement of anchors.

Aeroelastic Testing of Span-Wire Traffic Signal Systems

Span-wire traffic signals are vulnerable to extreme wind events such as hurricanes and thunder-storms. In past events in the Southeastern Coast of the United States, many failures of span-wire traffic signals were reported. In order to identify their dynamic behavior during extreme wind events and investigate their buffeting response, a large-scale aeroelastic testing was conducted at the NHERI Wall of Wind (WOW) Experimental Facility (EF) at Florida International University (FIU). The WOW is a large-scale open jet wind testing facility, comprised of 12 fans, and capa-ble of simulating winds at speeds up to 70 m/s, corresponding to a Category 5 hurricane. Follow-ing the Froude number criterion, a 1:10 aeroelastic model of a span-wire traffic signal system consisting of two 3-section and one 5-section signals was designed and constructed, based on the properties of its full-scale counterpart. In the testing protocol, various wind directions ranging between 0 and 180 degrees were considered at full-scale wind speeds ranging between 21 m/s and 42.5 m/s. The results of the aeroelastic tests show a similar behavior compared with previous full-scale tests conducted at the WOW. However, an increase in the RMS of accelerations was observed in comparison with those from the full-scale tests. This is attributed to the fact that the aeroelastic model enabled better simulation of low-frequency eddies in the turbulence spectrum compared to the full-scale testing turbulence spectrum.

On theory and methods for advanced detonation-driven hypervelocity shock tunnels.

This study describes theory and methods for developing detonation-driven shock tunnels in hypervelocity test facilities. The primary concept and equations for high-enthalpy shock tunnels are presented first to demonstrate the unique advantage of shock tubes for aerodynamic ground-based testing. Then, the difficulties in simulating flight conditions in hypervelocity shock tunnels are identified, and discussed in detail to address critical issues underlying these difficulties. Theory and methods for developing detonation drivers are proposed, and relevant progress that has advanced the state of the art in large-scale hypersonic test facilities is presented with experimental verifications. Finally, tailored conditions for detonation-driven shock tunnels are described, laying a solid foundation to achieve long test duration. This interface-matching key issue encountered in developing shock tunnels has been investigated for decades, but not solved for detonation drivers in engineering applications.

Thermal-Hydraulic Experimental Testing of the MYRRHA Wire-Wrapped Fuel Assembly

In recent years, extensive thermal-hydraulic experimental tests have been performed on the lead-bismuth eutectic (LBE)–cooled, wire-wrapped fuel assembly (FA) of MYRRHA. These thermal-hydraulic tests were performed using FA mock-ups in large-scale LBE experimental test facilities at SCK•CEN (Belgium), ENEA (Italy), and Karlsruhe Institute of Technology (Germany). The FA pressure drop characteristics and flow-induced vibration (FIV) characteristics were tested with a full-scale 127-pin mock-up test section. The existing pressure drop correlations of Rehme and of Cheng and Todreas (simplified model) predict the experimental pressure drop data very well and are considered suitable for use in the design and safety analysis of the MYRRHA system. FIVs are very limited in the wire-wrapped bundle, and fuel pin fatigue damage from vibration during operation is not expected. Further analysis and testing are required to determine if damage from fretting corrosion could be expected.Heat transfer characteristics of the FA were investigated experimentally in two separate 19-pin heated rod test sections cooled by LBE. The existing Kazimi-Carelli correlation predicts the global average Nusselt numbers very well, but the correlation is not developed to capture local hot spots. For the FA safety analysis, to further determine operational safety margins, a hot-spot factor is defined and analyzed to determine the hot-spot temperature penalty.

Experimental Investigation of Structural Response of Corrugated Steel Sheet Subjected to Repeated Impact Loading: Performance of LNG Cargo Containment System

The primary barrier in contact with LNG (Liquefied natural gas) cargo is manufactured from stainless steel, and has a corrugated membrane structure due to thermal deformation caused by extreme temperature differences. Because the primary barrier is tailored to be LNG watertight, the structural integrity of the primary barrier must be maintained despite the increase in LNG sloshing load. Among the various types of fluid impacts in a cargo hold, jet flow runs up along the wall of the cargo hold and extreme impact load is exerted on the side of the corrugation of the primary barrier. However, the impact behavior of the primary barrier under the prevailing environment has not been investigated due to the limitation of test methods. Thus, in the present study, the inelastic structural behavior of thin-walled and curved-shaped structures for liquefied natural gas cargo containment systems under repeated impact loading was investigated experimentally. Custom-built structural impact test equipment with large-scale weight drop test facilities was fabricated, and a series of structural impact tests were carried out. The impact energy and the number of repetitions were taken into account in order to investigate the characteristics of the inelastic structural behavior, such as plastic deformation and reaction force time history according to impact energy.

ESWIRP: European Strategic Wind tunnels Improved Research Potential program overview

“European Strategic Wind tunnel Improved Research Potential” ESWIRP was a project in the EU 7th Framework Program (FP7—Grant agreement no: FP7-227816), which was aiming at improving the performance capabilities of three strategic wind tunnels in Europe, by strengthening the cooperation between these wind tunnels in a new consortium. The research consortium members are Office National d’Etudes et de Recherches Aérospatiales (operating the S1MA as its largest sonic wind tunnel), German–Dutch wind tunnels [operating the large low-speed facility (LLF) as its largest low-speed wind tunnel], and European transonic wind tunnel (ETW) (operating its cryogenic wind tunnel). Together, these wind tunnels cover a wide range of experimental capabilities of relevance to civil aviation and aeronautical research in general. The project started in October 2009 for a period of 5 years. The European financial contribution was €7.2 million. The project consist of two major parts: (1) improvements to the testing infrastructure; and (2) the provision of wind tunnel access to research groups which do not usually have the means to access such large-scale test facilities. These topics also involved public dissemination and information activities. Although the tunnels covered in this project are of a complementary nature, the infrastructure activities were joined together, by a common representation of, and approach to, the tunnel performance characteristics. To this end, a generic model of a virtual wind tunnel was developed, enabling operators to assess the effect of the control parameters upon the testing conditions. The final aim of all participants was to provide the user community with an improved set of capabilities to test their innovative ideas. To provide better access to these three major wind tunnels, mainly research groups from European universities were contacted. The approach taken has included maximum transparency of the process and support of the researchers by the organizations responsible for the tunnels. In addition, when possible, we encouraged research groups to work together, to obtain the full benefit of economies of scale in research projects. ESWIRP responded to the targeted approach of the Integrating Activities of the FP7 Capacities Work Program: Networking activities, essentially focused around four topics: (1) organization of information campaigns, lectures and workshops to disseminate knowledge between the partners and future users. (2) Opening of a website for the consultation of wind tunnel standards. (3) Exchange of personnel between the Consortium partners, to foster the spread of good practices and the exchange of technical know-how. (4) Joint development of a reference wind tunnel parameter database. Trans-national access and/or testing services: after the call for proposals by the facility providers, groups of researchers had the opportunity to benefit from free wind tunnel services, including technical assistance to support the corresponding scientific research team(s). Joint research activities, innovative modeling of wind tunnels has helped designers to make better decisions, before the implementation of any novel hardware. Based on a generic finite volume type of modeling approach, the operational behaviour and the time-dependent flow quantities around the wind tunnel circuit have been simulated. Such model can be used, for example, to conceive and tune particular sub-system control laws, or explore the implications of hardware changes. Based on a common approach, dedicated models were developed for S1MA, LLF and ETW. The infrastructure improvements targeted the capability to obtain unsteady test data (with high accuracy) in the ETW, to improve the capability to simulate aircraft behaviour in ground effect in the LLF, and to establish a reliable closed-loop control of test Mach number in the S1MA wind tunnel. European Strategic Wind tunnels Improved Research Potential Program is European support for strategic wind tunnels, key research infrastructures in the development process of current and future aircraft. This is the first time that European authorities have given such support.

Stratification breakup by a diffuse buoyant jet: The MISTRA HM1-1 and 1-1bis experiments and their CFD analysis

Density stratification and its breakup are important phenomena to consider in the analysis of the hydrogen distribution during a severe accident. Many research projects to understand the stratification behavior have been performed with large and small scale test facilities. Many previous experimental studies, using helium as mimic gas of hydrogen, focused on the stratification breakup by a vertical or horizontal jet. However, in a real containment vessel, the upward flow pattern can be considered “diffuse” and buoyant neither pure jet nor pure plume. HM1-1 and HM1-1bis tests in the MISTRA facility were performed to investigate such erosive flow pattern created from a horizontal hot air jet impinging on a vertical cylinder. The experimental results indicated that the jet flow was quickly mixed with the surrounding gas in the lower region of the initial stratification, and deaccelerated by buoyancy force therein. Consequently, the erosive process became slower at the upper region of the initial stratification. Those observed behavior was analyzed using the computational fluid dynamics (CFD) techniques focusing on models for turbulent Schmidt Sct and Prndtl Prt numbers. Some previous studies mentioned that these numbers significantly change in the stratified flow. The changes of Sct and Prt are very important factor to predict the stratification erosion process. The results have indicated that the simulation can be much improved by using appropriate dynamic models for those numbers. This research is a collaboration activity between CEA and JAEA.

Improved Performance of Ballasted Rail Tracks Using Plastics and Rubber Inclusions

Current railroads require significant upgrading to meet the challenges of heavier loads at higher speeds. Due to excessive track degradation, the Australian rail industry spends large amounts on frequent track repair and maintenance, as well as ground improvement prior to track construction where soft and saturated subgrade soils pose considerable difficulties in design and construction. Moreover, the degradation of ballast particles under impact loading seriously hampers the safety and efficiency of rail tracks, which leads to speed restrictions and more frequent track upgrading. Hence, there is a need for innovative design solutions that can extend the service life of tracks to cater for faster and heavier train traffic. The use of planar geosynthetics and recycled rubber mats placed at the interface of ballast and subballast layer has proven an effective approach to mitigate ballast degradation and improve track longevity. This paper presents the current state-of-the-art knowledge of rail track geomechanics conducted at the University of Wollongong (UOW) including topics relating to laboratory testing and computational modeling approaches. The load-deformation responses of rubber mat/geogrid-stabilised ballast are studied in the laboratory using a large-scale drop weight impact testing facility, and Track Process Simulation Apparatus (TPSA). Numerical modelling using discrete element methods (DEM) are used to model geogrid-reinforced ballasted tracks, capturing both the discrete nature of ballast subject to various types of loading and boundary conditions. These results provide promising approaches to incorporate into the existing track design routines catering for future high speed and heavy haul trains.

Modeling and Control of the CSCEC Multi-Function Testing System

In order to promote the research and development on evaluating the seismic performance of structures, China State Construction Engineering Corporation (CSCEC) planned to construct a large-scale loading testing facility, the Multi-Function Testing System (MFTS). This facility can perform full-scale, real-time, 6-degree-of-freedom static and dynamic testing of rubber bearings and many types of structural components including long columns, shear walls and cross shape joints. The basic performances of the MFTS are a clearance of 9.1 m × 6.6 m × 10 m for specimen installation, maximum x-directional displacement 1500 mm, maximum y-directional velocity 1570 mm/s and maximum z-directional compressive load 108 MN. The system configuration and performance specifications of the MFTS are presented in this paper. The inverse kinematics model and the nonlinear model of the hydraulic servosystem of the MFTS are built. A modified feedback forward kinematics algorithm is developed for real-time control of the MFTS. Internal force characteristics of the loading system are analyzed. The internal force control method based on real-time solution of basis of internal force space is proposed for the system with large motion ranges. The motion controller combining position control loop and internal force control loop is developed. To meet the requirement of simultaneously imposing vertical compressive load and horizontal displacement, a mixed load and displacement controller is designed, where a direct force control loop is used to improve the response speed of the force control and reduce spatial dynamic coupling effects. Finally, a dynamic bearing testing is performed. The test results demonstrate that the system using the proposed controller has good abilities on position tracking, force balance, and load following.

A Database for the Experimental Study of Earthquake-Induced Liquefaction and Lateral Spreading in Sands

Centrifuge and large-scale testing in geotechnical engineering are very useful tools for modeling soil behavior under different loading conditions, particularly under earthquake loading. The paper presents an extensive database of nine centrifuge and large-scale liquefaction experiments performed both at the geotechnical centrifuge testing facility at Rensselaer Polytechnic Institute (RPI) and the large-scale testing facility at the University at Buffalo (UB). The database described herein was generated using the NEEShub online DataStore tool under the name “CENSEIS: Centrifuge and Large (Full)-Scale Modeling of Seismic Pore Pressures in Sands” (DOI: http://dx.doi.org/10.4231/D3GF0MX4F ). The paper discusses the tools and materials used in the experiments along with an explanation of each item in the database. Sample analyses are also presented in the paper to give an insight on the capabilities of the database for numerical and analytical applications. The paper is concluded with some possible applications along with tips and limitations of the database.

Towards guidelines for design of loose-laid roof pavers for wind uplift

Hurricanes are among the most costly natural hazards to impact buildings in coastal regions. Building roofs are designed using the wind load provisions of building codes and standards and, in the case of large buildings, wind tunnel tests. Wind permeable roof claddings like roof pavers are not well dealt with in many existing building codes and standards. The objective of this paper is to develop simple guidance in code format for design of loose-laid roof pavers. Large-scale experiments were performed to investigate the wind loading on concrete roof pavers on the flat roof of a low-rise building in Wall of Wind, a large-scale hurricane testing facility at Florida International University. They included wind blow-off tests and pressure measurements on the top and bottom surfaces of pavers. Based on the experimental results simplified guidelines are developed for design of loose-laid roof pavers against wind uplift. The guidelines are formatted so that use can be made of the existing information in codes and standards such as American Society of Civil Engineering (ASCE) 7-10 standard\'s pressure coefficients for components and cladding. The effects of the pavers\' edge-gap to spacer height ratio and parapet height to building height ratio are included in the guidelines as adjustment factors.

<i>In Situ</i> Observation of Stress Accumulation during Sub-Merged Arc Welding

Results obtained from laboratory tests mostly need to be verified under fabrication conditions in order to incorporate design specifics (joint configuration and restraint), which effect the residual stress state considerably. For this purpose, multi-pass sub merged arc welding was performed in a special large-scale testing facility. The impact of varying interpass temperatures could be proven in-situ by means of a pronounced stress accumulation during welding and subsequent heat treatment accompanied by stress determination using X-ray diffraction.

A phased approach to enable hybrid simulation of complex structures

Hybrid simulation has been shown to be a cost-effective approach for assessing the seismic performance of structures. In hybrid simulation, critical parts of a structure are physically tested, while the remaining portions of the system are concurrently simulated computationally, typically using a finite element model. This combination is realized through a numerical time-integration scheme, which allows for investigation of full system-level responses of a structure in a cost-effective manner. However, conducting hybrid simulation of complex structures within large-scale testing facilities presents significant challenges. For example, the chosen modeling scheme may create numerical inaccuracies or even result in unstable simulations; the displacement and force capacity of the experimental system can be exceeded; and a hybrid test may be terminated due to poor communication between modules (e.g., loading controllers, data acquisition systems, simulation coordinator). These problems can cause the simulation to stop suddenly, and in some cases can even result in damage to the experimental specimens; the end result can be failure of the entire experiment. This study proposes a phased approach to hybrid simulation that can validate all of the hybrid simulation components and ensure the integrity large-scale hybrid simulation. In this approach, a series of hybrid simulations employing numerical components and small-scale experimental components are examined to establish this preparedness for the large-scale experiment. This validation program is incorporated into an existing, mature hybrid simulation framework, which is currently utilized in the Multi-Axial Full-Scale Sub-Structuring Testing and Simulation (MUST-SIM) facility of the George E. Brown Network for Earthquake Engineering Simulation (NEES) equipment site at the University of Illinois at Urbana-Champaign. A hybrid simulation of a four-span curved bridge is presented as an example, in which three piers are experimentally controlled in a total of 18 degrees of freedom (DOFs). This simulation illustrates the effectiveness of the phased approach presented in this paper.