Modeling and Simulation of Static and Dynamic Behavior of Soil Structure Systems Boris Jeremić Feng, Yang, Behbehani, Sinha, Wang, Pisanó, Abell University of California, Davis Lawrence Berkeley National Laboratory GeoMEast2018 Cairo, Egypt
Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Motivation Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Motivation Motivation Improve modeling and simulation for infrastructure objects Use select fidelity (high low) numerical models to analyze static and dynamic behavior of soil/rock structure fluid systems Reduction of modeling uncertainty, ability to perform desired level of sophistication modeling and simulation Accurately follow the flow of input and dissipation of energy in a soil structure system Development of an expert system for modeling and simulation of Earthquakes, Soils, Structures and their Interaction, : http://real-essi.info/
Motivation Predictive Capabilities Prediction under Uncertainty: use of computational model to predict the state of SSI system under conditions for which the computational model has not been validated. Verification provides evidence that the model is solved correctly. Mathematics issue. Validation provides evidence that the correct model is solved. Physics issue. Modeling and parametric uncertainties are always present, need to be addressed Goal: Predict and Inform rather than (force) Fit
Motivation Motivation: Modeling Uncertainty Simplified modeling: Features (important?) are neglected, simplified out (6C ground motions, inelasticity) Modeling Uncertainty: unrealistic (unnecessary?) modeling simplifications Modeling simplifications are justifiable if one or two level higher sophistication model shows that features being simplified out are not important
Motivation Uncertainties Modeling uncertainty, introduced by simplifying assumptions low sophistication modeling and simulation medium sophistication modeling and simulation high sophistication modeling and simulation choice of sophistication level for confidence in analysis results Parametric uncertainty, propagation of uncertainty in material, K ep propagation of uncertainty in loads, F(t) results are PDFs and CDFs for
Motivation Modeling Uncertainty Simplified modeling: Features (important?) are neglected (3C, 6C ground motions, inelasticity) Modeling Uncertainty: unrealistic and unnecessary modeling simplifications Modeling simplifications are justifiable if one or two level higher sophistication model shows that features being simplified out are not important
Motivation Parametric Uncertainty: Soil Stiffness Young s Modulus, E (kpa) 30000 25000 20000 15000 10000 5000 E = (101.125*19.3) N 0.63 Normalized Frequency 0.00008 0.00006 0.00004 0.00002 5 10 15 20 25 30 35 SPT N Value 10000 0 10000 Residual (w.r.t Mean) Young s Modulus (kpa) Transformation of SPT N-value: 1-D Young s modulus, E (cf. Phoon and Kulhawy (1999B))
0.12 0.10 0.08 0.06 0.04 0.02 0.00 20 25 30 35 40 45 50 55 60 Friction Angle [ ] 0.25 0.20 0.15 0.10 0.05 0.00 20 25 30 35 40 45 50 55 60 Friction Angle [ ] 0.0035 0.0030 0.0025 0.0020 0.0015 0.0010 0.0005 0.0000 0 200 400 600 800 1000 1200 1400 Undrained Shear Strength [kpa] 0.045 0.040 0.035 0.030 0.025 0.020 0.015 0.010 0.005 0.000 0 50 100 150 200 250 300 Undrained Shear Strength [kpa] Motivation Parametric Uncertainty: Material Properties Probability Density function Min COV Max COV Cumulative Probability Density function 1.0 0.8 0.6 0.4 0.2 Min COV Probability Density function Min COV Max COV Cumulative Probability Density function 1.0 0.8 0.6 0.4 0.2 Min COV Max COV Max COV 0.0 10 20 30 40 50 60 70 80 Friction Angle [ ] 0.0 0 200 400 600 800 1000 1200 1400 Undrained Shear Strength [kpa] Field φ Field c u Min COV Max COV 1.0 Min COV Max COV 1.0 Probability Density function Cumulative Probability Density function 0.8 0.6 0.4 0.2 Probability Density function Cumulative Probability Density function 0.8 0.6 0.4 0.2 Min COV Min COV Max COV Max COV 0.0 10 20 30 40 50 60 70 80 Friction Angle [ ] 0.0 0 50 100 150 200 250 300 350 400 Undrained Shear Strength [kpa] Lab φ Lab c u
Motivation Motivation: Seismic Hazard
Motivation Motivation: Egypt Seismic Design Accelerations
Simulator System Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Simulator System Simulator System The, (Realistic Modeling and Simulation of Earthquakes, Soils, Structures and their Interaction) Simulator is a software, hardware and documentation system for high fidelity, high performance, time domain, nonlinear/inelastic, deterministic or probabilistic, 3D, finite element modeling and simulation of: statics and dynamics of soil, statics and dynamics of rock, statics and dynamics of structures, statics of soil-structure systems, and dynamics of earthquake-soil-structure system interaction
Simulator System Simulator System System Components Pre-processor (gmsh/gmessi, X2ESSI) Program (local, remote, cloud) Post-Processor (Paraview, Python, Matlab) System availability: Educational Institutions: Amazon Web Services (AWS), free Government Agencies, National Labs: AWS GovCloud Professional Practice: AWS, commercial Short Courses (online) System description and documentation at http://real-essi.info/
Simulator System Trusting Simulation Tools, Quality Assurance Full verification suit for each element, model, algorithm Certification in progress for NQA-1 and ISO-90003-2014 Verification: Mathematics issue. Verification provides evidence that the model is solved correctly. Validation: Physics issue. Validation provides evidence that the correct model is solved.
Simulator System Importance of Verification and Validation (V&V) V & V procedures are the primary means of assessing accuracy in modeling and computational simulations V & V procedures are the tools with which we build confidence and credibility in modeling and computational simulations
Simulator System Verification and Validation Real World Conceptual Model Highly accurate solution Analytical solution Benchmark ODE solution Benchmark PDE solution Computational Model Computational Solution Experimental Data Unit Problems Benchmark Cases Subsystem Cases Complete System Verification Validation Oberkampf et al.
Energy Dissipation Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Energy Dissipation Energy Input and Dissipation Energy input, static and dynamic forcing Energy dissipation outside SSI domain: SSI system oscillation radiation Reflected wave radiation Energy dissipation/conversion inside SSI domain: Inelasticity of soil, contact zone, structure, foundation, dissipators Viscous coupling with internal/pore fluids, and external fluids Numerical energy dissipation/production
Energy Dissipation Incremental Plastic Work: Negative incremental energy dissipation Plastic work is NOT plastic dissipation
Energy Dissipation Energy Dissipation on Material Level Single elastic-plastic element under cyclic shear loading Difference between plastic work and dissipation Plastic work can decrease, dissipation always increases
Energy Dissipation Plastic Free Energy Multi-scale effect of particle interlocking/rearrangement Strain energy on particle level
Energy Dissipation Energy Transformation in Elastic-Plastic Material
Energy Dissipation Energy Dissipation Control Mechanisms 500 Kinetic Energy 500 Kinetic Energy 500 Kinetic Energy Strain Energy Strain Energy Strain Energy 400 Plastic Free Energy Plastic Dissipation 400 Plastic Free Energy Plastic Dissipation 400 Plastic Free Energy Plastic Dissipation Viscous Damping Viscous Damping Viscous Damping Numerical Damping Numerical Damping Numerical Damping Energy [MJ] 300 200 Input Work Energy [MJ] 300 200 Input Work Energy [MJ] 300 200 Input Work 100 100 100 0 0 2 4 6 8 10 Time [s] 0 0 2 4 6 8 10 Time [s] 0 0 2 4 6 8 10 Time [s] Plasticity Viscous Numerical
Energy Dissipation Energy Dissipation Control Energy [MJ] 2000 1750 1500 1250 1000 750 Kinetic Energy Strain Energy Plastic Free Energy Plastic Dissipation Viscous Damping Numerical Damping Input Work 500 250 0 0 2 4 6 8 10 Time [s]
Energy Dissipation Inelastic Modeling for Soil Structure System Soil elastic-plastic Dry, single phase Unsaturated (partially saturated) Fully saturated Contact, inelastic, soil/rock foundation Dry, single phase, Normal (hard and soft, gap open/close), Friction (nonlinear) Fully saturated, suction and excess pressure (buoyant force) Structural inelasticity/damage Nonlinear/inelastic fiber beams Nonlinear/inelastic reinforced concrete walls. plates, shells Alcali Silica Reaction concrete modeling
Energy Dissipation NPP Model Auxiliary Building Containment Building Damping Layers Center of ESSI Box Foundation Damping Layers Contact Soil DRM Layer
Energy Dissipation Structure Model The nuclear power plant structure comprise of Auxiliary building, f aux 1 = 8Hz Containment/Shield building, f cont 1 = 4Hz Concrete raft foundation: 3.5m thick Figure: Auxiliary and Containment Building
Energy Dissipation Inelastic Soil and Inelastic Contact Shear velocity of soil V s = 500m/s Undrained shear strength (Dickenson 1994) V s [m/s] = 23(S u [kpa]) 0.475 For V s = 500m/s Undrained Strength S u = 650kPa and Young s Modulus of E = 1.3GPa von Mises, Armstrong Frederick kinematic hardening (S u = 650kPa at γ = 0.01%; h a = 30MPa, c r = 25) Soft contact (concrete-soil), gaping and nonlinear shear 1000 2 1e10 Stress σ [kpa] 500 0 500 Stiffness K n [N/m] 1 1000 20 10 0 10 20 Strain ǫ [%] 0 0.0 0.5 1.0 Penetration δ n [mm]
Energy Dissipation Acc. Response, Top of Containment Building 1 Elastic Inelastic 1 Elastic Inelastic 1 Elastic Inelastic A x [g] 0 A y [g] 0 A z [g] 0 1 0 10 20 30 40 Time [s] 0.10 Elastic Inelastic 1 0 10 20 30 40 Time [s] 0.10 Elastic Inelastic 1 0 10 20 30 40 Time [s] 0.10 Elastic Inelastic FFT A x [g] 0.05 FFT A y [g] 0.05 FFT A z [g] 0.05 0.00 0 5 10 15 20 Frequency [Hz] 0.00 0 5 10 15 20 Frequency [Hz] 0.00 0 5 10 15 20 Frequency [Hz]
Energy Dissipation Acceleration Traces, Elastic vs Inelastic 100 24 100 24 1g 1g A 22 A 22 50 50 B 20 B 20 0 C 18 0 C 18 Depth [m] D 16 Time [s] Depth [m] D 16 Time [s] 50 E 14 50 E 14 F F 12 12 100 G 100 G 10 10 150 150 100 50 0 50 100 150 Width [m] 8 150 150 100 50 0 50 100 150 Width [m] 8
Energy Dissipation Energy Dissipation in NPP Model (MP4)
Slab Flange Web Energy Dissipation Wall, Regular and ASR Concrete 1000 ESSI Experiment 1000 ESSI Experiment Shear Force [kn] 500 0 500 Shear Force [kn] 500 0 500 1000 1000 6 4 2 0 2 4 6 8 Horizontal Displacement [mm] 8 6 4 2 0 2 4 6 Horizontal Displacement [mm]
Coupled Systems Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Coupled Systems Fully Coupled Formulation, u-p-u Fully saturated soil Partially, un-saturated soil
Coupled Systems Fully Coupled Formulation, u-p-u
Coupled Systems Liquefaction as Base Isolation, Model
Coupled Systems Liquefaction, Wave Propagation
Coupled Systems Liquefaction, Stress-Strain Response
Coupled Systems Pile in Liquefiable Soil, Model z x Lumped Mass Nonlinear Beam Column Element 6 m upu Element e1 e2 Elastic Beam Column Element A9 B9 3 m 12 m e3 e4 e5 e6 e7 e8 C9 D9 E9 F9 G9 H9 I9 15 m Pile ui Ui p Beam u p U solid 12 m θi
Coupled Systems Pile in Liquefiable Soil, Results
Introduction Inelasticity Coupled Systems Dam, 3D Slope Stability Jeremic et al. Seismic Motions Summary
Coupled Systems Solid/Structure-Fluid Interaction: gmfoam Mesh separation integrated geometry model FEM & FVM mesh conversion handle discontinuous mesh Incorporate gmessi Interface geometry extraction Interface class SSFI in SSFI OpenFoam Fluid Domain (water) Fluid Domain (air) Solid Domain
Coupled Systems Solid/Structure-Fluid Interaction, Example (MP4)
6C vs 1C Motions Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
6C vs 1C Motions 3D (6D) Seismic Motions All (most) measured motions are full 3C (6C) One example of an almost 2D motion (LSST07, LSST12)
6C vs 1C Motions Regional Geophysical Models Free Field seismic motions on regional scale Knowledge of geology (deep and shallow) needed USGS
6C vs 1C Motions ESSI: 6C or 1C Seismic Motions Full 6C (3C) motions, recorded only in 1C Develop vertically propagating shear wave, 1C Apply 1C shear wave to ESSI system
6C vs 1C Motions 6C Realistic Ground Motions Free field seismic motion models (MP4)
6C vs 1C Motions 6C Realistic Ground Motions (closeup) (MP4)
6C vs 1C Motions 6C vs 1C Free Field Motions One component of motions (1D) from 3D Excellent fit (MP4) (MP4)
6C vs 1C Motions 6C vs 1C NPP ESSI Response Comparison (MP4)
Stress Test Motions Outline Introduction Motivation Simulator System Inelasticity Energy Dissipation Coupled Systems Seismic Motions 6C vs 1C Motions Stress Test Motions Summary
Stress Test Motions Stress Testing SSI Systems Excite SSI system with a suite of seismic motions Waves: P, SV, Sh, Surface (Rayleigh, Love, etc.) Variation in inclination, frequency, energy and duration Try to "break" the system, shake-out strong and weak links L o L w L o L w L o L w
Stress Test Motions Stress Test Source Signals Ricker Ricker2nd Function Amplitude 0.003 0.002 0.001 0-0.001-0.002-0.003-0.004-0.005 0 2 4 6 8 10 12 14 16 18 20 Time [s] Ricker2nd FFT Amplitude 0.00016 0.00014 0.00012 0.0001 8e-05 6e-05 4e-05 2e-05 0 0 2 4 6 8 10 Frequency [Hz] Ormsby Ormsby Function Amplitude 0.12 0.1 0.08 0.06 0.04 0.02 0-0.02-0.04 0 1 2 3 4 5 6 Time [s] Ormsby FFT Amplitude 0.0005 0.00045 0.0004 0.00035 0.0003 0.00025 0.0002 0.00015 0.0001 5e-05 0 0 5 10 15 20 25 30 Frequency [Hz]
Stress Test Motions Free Field, Variation in Input Frequency, θ = 60 o (MP4)
Stress Test Motions SMR ESSI, Variation in Input Frequency, θ = 60 o (MP4)
Stress Test Motions SMR ESSI, 3C vs 3 1C (OGV)
Stress Test Motions Free Field vs ESSI - Different Frequencies B A C Acceleration response - Surface center point A X direction Z direction A x [g] A z [g] 0.50 0.25 0.00 0.25 SMR Free field 0.50 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] 0.50 0.25 0.00 0.25 SMR Free field 0.50 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] A x [g] A z [g] 60 30 0 30 SMR Free field 60 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] 60 30 0 30 SMR Free field 60 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] A x [g] A z [g] 60 30 0 30 SMR Free field 60 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] 60 30 0 30 SMR Free field 60 0.0 0.2 0.4 0.6 0.8 1.0 Time [s] (a) f = 1Hz θ = 60 o (b) f = 5Hz θ = 60 o (c) f = 10Hz θ = 60 o
Summary Summary Numerical modeling to predict and inform, rather than fit Education and Training is the key! Funding from and collaboration with the US-DOE, US-NRC, CNSC-CCSN, US-NSF, Caltrans, UN-IAEA, and Shimizu Corp. is greatly appreciated, /MS-ESSI Simulator System: http://real-essi.info/ Lecture Notes, Book: http://sokocalo.engr.ucdavis.edu/~jeremic/ LectureNotes/