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Advanced Site Monitoring and Characterization of Site Dynamic Properties. Mourad Zeghal, Tarek Abdoun and Vicente Mercado Department of Civil and Envir . Eng., Rensselaer Polytechnic Institute, Troy, NY Anirban De Manhattan College. Quake Summit 2010, October 8 - 9, 2010. Outline.
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Advanced Site Monitoring and Characterization of Site Dynamic Properties Mourad Zeghal, TarekAbdoun and Vicente Mercado Department of Civil and Envir. Eng., Rensselaer Polytechnic Institute, Troy, NY Anirban De Manhattan College Quake Summit 2010, October 8 - 9, 2010.
Outline • Introduction and Objectives • Shape-Acceleration Array • New Array at Wildlife Refuge Site • Recent Earthquake and Field Test • Data Reduction and System Identification • Concluding Remarks
Introduction • Evaluation of in-Situ Soil Dynamic Properties
Introduction • Evaluation of Soil Dynamic and nonlinear Properties: soil sample tests • How representative of in-situ conditions: • Stress-strain response (damping, etc.) • Lateral spreading and failure
Objectives • Install permanently a network of Shape-Acceleration Arrays (SAAs) with an optimal configuration at the NEES Wildlife refuge site • Monitor the site response (acceleration, permanent displacement and pore pressure) • Future earthquakes (lateral spreading expected) • Field test(s) using T-Rex • Develop efficient data reduction and system identification tools to evaluate the in situ 3D dynamic and nonlinear properties of the site
Shape Acceleration Array 3D measurements • Accelerations • Permanent displacements
NEES Wildlife Refuge Site • Imperial Valley of Southern California • Experienced multiple earthquakes and liquefaction and lateral spreading events in the past
NEES Wildlife Refuge Site • Granular layer anticipated to liquefy during medium-size earthquakes • Significant lateral spreading expected
Shape Acceleration Array Optimal configuration: analytical considerations and numerical simulations
Multi-Dimensional Local Identification • CMP: Control Motion Approach (prescribed motion at all sensor “node” locations, Elmikaty and Zeghal) • CMP Finite Element formulation Interior node Boundary node
Constitutive Model (Saturated Clay) Prevost, 1987 • Von-Mises yield criteria, multi-yield surfaces • Associated flow rule • Kinematic Hardening rule • Shear Modulus Degradation and Reduction • Visco-Elasto-Plastic Stress-Strain relation • Identification Parameters
Concluding Remarks Work in progress to develop a capability to: • measure cyclic and permanent displacements of field sites • Efficiently characterize and estimate (low and large strain) three-dimensional in situ dynamic properties Objective: Enable better understanding of liquefaction, lateral spreading and failure of sites
Acknowledgements • This research is supported by the National Science Foundation (NEESR CMS-0830325) • NEES@UCSB • NEES@UTexas