Equipment Site Description

Transcription

1 Equipment Site Description The primary objective of this project is to create a facility in which a full-scale subassembly can be subjected to complex loading and imposed deformation states at multiple connection points on the subassembly, including the connection between the structure and its foundation. The MUST-SIM facility will have the following unique features: (i) 6-DOF load and position control at multiple connection points, (ii) system modularity to allow for easy expansion and low-cost maintenance/operation, (iii) multiple dense arrays of non-contact measurement devices, and (iv) advanced visualization and data mining capabilities for integrated teleoperation and teleobservation (telepresence), as shown in Figure D The facility will realize the above features through the development of six-dof Loading and Boundary Condition Boxes (LBCB) that allow for precise application of complex load and boundary conditions. The LBCBs will be able to impose motions on the test structures that are determined from the results of concurrently running numerical models of the test specimen and the surrounding structure/foundation/soil system employing pseudo-dynamic testing methods. Dense arrays of state-of-the-art, non-contact instrumentation, will allow near real-time model updating for the model-based simulation. In addition, this facility and its teleoperation capabilities will be enhanced by development of multi-function data visualization and knowledge interpretation tools in cooperation with the Automated Learning Group of the National Center for Supercomputing Applications (NCSA). Structural Finite Element Analysis Sectional Actions/Deformations at Contact Points Geotechnical Finite Element Analysis User Decision Non-Contact Three Non-contact Displacement Measurements Instrumentation Systems Data Visualization and Knowledge Integration Data Comparison, Analysis, and Decision Making Figure D.12-1: Principal components and information flow in the MUST-SIM Facility The distributed simulation and control software developed by the MUST-SIM team enables not only the utilization of the best available geotechnical and structural testing sites regardless of their geographical location, but also avails of the opportunity to deploy the best features of a number of analytical tools in one system analysis. The current version of this software controls four stations which could be physical or analytical simulation sites. In Figure D.12-2, a three-site simulation is depicted, where Sites A and B are physical and Site C is analytical. This schema is currently being applied to a multi-site test in collaboration with the System Integration (SI) team, and the University of Colorado. Page 1 of 5

2 Site A Site B Servo-Controller Simulation Coordinator Servo-Controller D N R N Hydraulic Actuator Hydraulic Actuator Site C Figure D.12-2: Schema for a Three-Site Test including NEESgrid Software Products The three loading and boundary condition boxes (LBCBs), shown in Figure D.12-3, have 3000, 1500 and 4500 kn load capacities in the two horizontal and one vertical directions. The corresponding deformation capabilities are 125mm, 250mm and degrees rotation. The boxes can be anchored at any of 3 sides to either wall or floor, thus providing a versatile and adaptable experimental set up. The individual depicted next to the boxes is to give an indication of scale. Figure D.12-3: Full scale Loading and Boundary Condition Box (LBCB) An L-shaped reaction structure is an integral part of the facility. Its location with respect to the strong floor in the Newmark Laboratory is shown in Figure D The wall is 50x29 feet, and has a height of 23 feet. It is designed to resist the maximum force from the LBCB when placed at the top left corner and can also support all three LBCBs reacting against the wall at the same time. Page 2 of 5

3 50 5 NEES Zone Figure D.12-4: Location and Dimensions of Reaction Wall The development, calibration, and validation of comprehensive numerical models require a density of experimental test data that is similar to the density of elements used in numerical simulation models. While conventional instruments such as strain gauges and displacement transducers have been the mainstay in structural research, the effort, expense, and space required by each of these gauges limits their usefulness in collecting the detailed data that is necessary for model validation and verification. Over the last few years, there has been a tremendous growth in the capabilities of non-contact instrumentation methods for measuring displacements and strains at a very large numbers of individual points. The three non-contact measurement technologies that have been identified for use in the MUST-SIM Facility are summarized below. The Krypton s RODYM Dynamic Measurement Machine is able to measure the position of up to 256 small (8 gram and 8 mm diameter) light emitting diode markers in three-dimensional space to an accuracy of plus/minus 0.02 mm at a sampling rate of up to 3000 individual readings per second. The Krypton system consists of a portable housing containing three 2048 CCD line-element cameras. The camera system has an effective measurement volume of 17 m 3. No calibration of the system is required by external researchers. The Stress Photonics Gray Field Polariscope (GFP-1200) is a full field non-contact stress/strain measurement system that is based on the principles of photoelasticity. To use Stress Photonics Grey-Field Polariscope, an application of a thin (0.25 mm) plastic coating (photoelastic material/epoxy) is applied to the surface of the test specimen. A light source is then used to emit circular polarized light and a digital camera is used to measure the fringe patterns. Unlike with traditional photoelasticity, the GFP-1200 system measures small variations in patterns of circular light. As a result, reliable sub-fringe level accuracy can be obtained with high resolution in the stress/strain levels being resolved. A three-color system enables the system to compensate for variations in the thickness of the coating. The plastic coating does not creep; hence it is possible to stop a test for multiple days without a concern for loss of accuracy. Close-Range Digital Photogrammetry is used as a third non-contact measurement methodology. Widely used in aerial mapping, this methodology has recently become increasingly popular for other applications in the field of engineering and solid modeling. In a structural engineering application, the system can be used to measure the movements of targets placed on the surface of the test specimen from which strains, crack widths, and other features can be determined. High accuracies can be obtained by capturing subsequent images through conventional and digital cameras. Over the last few years there has been a major increase in the quality of digital cameras and image analysis tool while there has been a significant decrease in the cost of these tools. State-of-the-art software for structural and geotechnical analysis is being assembled from the work of the Project Team and also work within other NEES facilities. The software is being integrated with the testing and control Page 3 of 5

4 software to deliver capabilities of modeling complex structures and materials alongside foundation materials, as well as deformation and failure of the foundation. This will drive the test in an online computer-controlled manner using recent development in algorithms that take into account the characteristics of the loading system (actuators, servovalves, etc.). Current developments are based on a dual approach of utilizing simple MatLab analysis software for simple frame analysis whilst developments of control algorithms fully integral with the finite element analysis package ABAQUS is nearing completion. Figure D.12-5 shows the MUST-SIM development of a 3-site distributed simulation based on Matlab, and intended for use in the SI-UIUC-Colorado collaborative test. Figure D.12-5: MatLab-based Simulation Controller Developed by MUST-SIM for Distributed Testing Multi-function data visualization and knowledge interpretation tools are being developed for the NEES site with the Automated Learning Group of the National Center for Supercomputing Applications (NCSA). This will be accomplished in four stages: (i) visualization, (ii) integration and interpretation of multiple-source test data, (iii) integration of test and analysis information, and (iv) model adjustment and optimization. Teaming with NCSA in developing visualization tools ensures the efficacy of the project. Finally, the control and telepresence system does a three-level algorithm comprising network (supervisory), link, and servo levels, affording full teleobservation and teleoperation capabilities in an open, easy-to-modify architecture. The three-level control system provides high levels of safety in terms of teleoperation of such large facility. The PIs and the Project Team have an established record in all aspects outlined above (online dynamic testing, instrumentation, analysis, visualization, and control). Education and training is a vital component of the MUST-SIM vision. Towards this end, an interactive web site is under development where users can access a kinematic simulator of the LBCBs, shown in Figure D.12-6, and can run virtual experiments. A second stage in the educational learning curve is use of a fully-functional 5:1 scale LBCB (Figure D.12-6) where testing scenarios may be played whilst providing an analytical representation of the rest of the structure-foundation-soil system. The above-mentioned two-stage approach is not only for engineering students and other groups, but is also part of the advanced user-training program of the Facility. Page 4 of 5

5 Position Command PID Shore Western Load Command PID G -1 x l Act G Structure l x outer loop inner loop LBCB Figure D.12-6: Kinematic Simulator (left) and 5:1 Scale Box (right) for Education and Training The MUST-SIM facility provides a total testing-analysis-visualization-display environment that combines the ability to test portions of structures under complex and continuously changing boundary and loading conditions with the ability to either model or indeed test the SSI feature of response. This is achieved through high precision application of six degrees of freedom with very high precision in both forces and displacements. Therefore, it is a NEES asset that has hitherto not been available. From the instrumentation viewpoint, there is a serious and clearly identified gap between the level of information obtained from advanced analysis and that from laboratory testing. This gap has hindered convincing and intensive calibration of software where only one or two response parameters, usually displacements, are compared to test results. The instrumentation component of this facility bridges this gap and provides, in addition to high resolution control of the test, detailed information on structural performance that enables the real calibration and enhancement of analysis software. The density of the instrumentation program for a test specimen will be comparable to that of a finite element idealization. The integration of the test with the analysis software, through extensive instrumentation using new non-contact technologies alongside traditional strain gauging and LVDTs, renders the facility novel in this respect too. The MUST-SIM NEES facility will stimulate new and unique approaches to research to address earthquake engineering issues through a collaborative shared-use testing environment, ultimately leading to improved seismic performance of our infrastructure, reduced economic losses in natural disasters, and more reliable structures. Moreover, the MUST-SIM NEES facility, with its state-of-the-art components, will be fully integrated with the undergraduate and graduate programs of the Department of Civil and Environmental Engineering at the University of Illinois at Urbana-Champaign and will feature in demonstrations to minority and under-represented groups of potential students. Therefore, the wider impacts of this NEES facility are in developing advanced and reliable criteria for upgrading the existing infrastructure systems and the design of new systems, and in educating engineers and engineering students in earthquake testing, analysis, instrumentation, visualization and ultimately, in seismic risk assessment and reduction. Page 5 of 5