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Virtual Experiments for Teaching Hysteretic Structural Behavior. Shirley J. Dyke, Nestor Castaneda, and Zach Feinstein Washington University in St. Louis (NEESR-CABER Project). Outline. Goals and Vision Instructional Objectives Framework for the “Virtual” Experiment
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Virtual Experiments for Teaching Hysteretic Structural Behavior Shirley J. Dyke, Nestor Castaneda, and ZachFeinstein Washington University in St. Louis (NEESR-CABER Project)
Outline • Goals and Vision • Instructional Objectives • Framework for the “Virtual” Experiment • Current Limitations and Future Plans • Acknowledgements
Objective “Provide undergraduate students with an inquiry-based educational tool to understand the assumptions used in numerical modeling and their implications by performing a comparison of numerical and experimental data.”
Vision “Provide a unified framework to support the development of a series of virtual experiments created within the NEES network using the shared data repository and cyber-infrastructure capabilities.”
Instructional Objectives • Users select the dimensions of the column they want to examine, e.g. the column geometry, section details, and material properties. • Two different analysis methods (linear and non-linear structural behavior) are implemented to consider different modeling assumptions. • A comparison between numerical and experimental results can be performed.
Framework for “Virtual” Exercise • NTCP communication protocol is used to send model parameters from client to the server site. • Server site will perform analysis (openSEES) and send output files to RBNB by using FTP (File Transfer Protocol) • Standard TCP/IP communication protocol is performed between RBNB and client site to send experimental and numerical data to the client. • Visualization and further data analysis can be performed by using RDV interface.
Components: Experimental Data • Sample data provided from tested column • Height= 3.6m, diameter=60cm • Lateral loads applied using a hydraulic actuator • Strains and displacements are measured
Components: OpenSEES • One option (opensource and integrated with NEES cybertools) for modeling hysteretic structural behavior • Used for the numerical simulation component of the virtual exercise • Used to model the hysteretic structural behavior of reinforced concrete columns using a nonlinear and linear beam-column element.
Numerical Model Description • Single 2-D non-linear Beam-Column element. 6 DOF – 3 Free – 3 Constraints (Base) • Radial Fiber section - 23 and 4 rings in the core and cover, respectively, plus 20 wedges.
Numerical Model Description • Concrete was modeled with “OpenSees Concrete 02 model”. • Steel was modeled with “OpenSees Steel 02 model” • Gravity effects are modeled applying a compression load at the tip of the column equivalent to the self-weight. • No confinement and P-Delta effects are modeled.
Components: RDV –Control Panel • A GUI is available for the students to set up, run and visualize the numerical simulation. • Using RDV (real-time data viewer) students may plot and extract the numerical and experimental results for comparisons.
Implementation • This experiment has been implemented by two sets of students, UConn and WashU. • Feedback was solicited and is being incorporated into the tool.
Limitations • Currently the system does not support multiple simultaneous OpenSees analyses. • “Start” button re-enabled each 60 seconds, independently of actual run time for each simulation. • Limits must be set for some model parameters within a reasonable range to ensure convergence.
Future Plans • Video from the structural testing will be integrated into the tool in the future. • Increase variety of experimental data sources to give students better variety for comparisons. • Increase the number of numerical analysis options based on different modeling assumptions.
Future Plans • Improve server capacities to run OpenSees using multiple simultaneous runs and avoid unnecessary delays. • Implementation of a more robust communication protocol between RBNB and client site.
Integration with NEES EOT • Cyberinfrastructure capabilities facilitate remote participation and operation of experiments or simulations, including geographically distributed and hybrid simulations. • “Virtual” experiments may involve research tools, real-world data and cyberinfrastructure capabilities, encouraging students to gain experience with these capabilities. • A broader set of students and institutions can access virtual tools, improving engineering education globally.
Acknowledgments • Funding has been provided in part by NSF Grants CMS-0530737 (NEESR Program) and CMS-0625640. • NSF Research Experiences for Undergraduates (NSF EEC–0353718). • Prof. D.J. Belarbi, Dr. Sang-Wook Bae and Suriya Prakash for providing experimental data for this virtual exercise • NEESit staff for technical support