A Brief Overview of the NEESgrid Simulation Platform OpenSees: Application to the Soil Foundation Structure Interaction Problems

Transcription

1 A Brief Overview of the NEESgrid Simulation Platform OpenSees: Application to the Soil Foundation Structure Interaction Problems Boris Jeremić Department of Civil and Environmental Engineering University of California, Davis Third UJNR Workshop on Soil-Structure Interaction March 9-3, 4, Vallombrosa Center, Menlo Park, California Supported in part by the NSF, PEER, Caltrans, and Cal EPA. Collaborators: Professors Zhaohui Yang (UAA), Sashi Kunnath (UCD), Gregory Fenves (UCB), Jacobo Bielak (CMU), Drs. Francis McKenna (UCB), and research students Xiaoyan Wu (UW) Ritu Jain (UCD), Jinxiu Liao (UCD). Jeremić, 3rd UJNR Workshop 1

2 Leitmotiv Create high fidelity models of constructed facilities (bridges, buildings, port structures, dams...). Models will live concurrently with the physical system they represent. Models to provide owners and operators with the capabilities to assess operations and future performance. Use observed performance to update and validate models through simulations. Jeremić, 3rd UJNR Workshop

3 Presentation Overview The NEES MiniGrand Challenge Project Validation experiments Simulation challenge OpenSees NEESgrid simulation platform Template Elasto Plasticity Full Coupling of Solid and Fluid Seismic Motions (FEM input) Distributed Memory Parallel Computing General Large Deformations Jeremić, 3rd UJNR Workshop 3

4 Validation Experiments A validation experiment should be jointly designed and executed by experimentalist and computationalist Need for close working relationship from inception to documentation Elimination of typical competition between each Complete honesty concerning strengths and weaknesses of both experimental and computational simulations A validation Experiment should be designed to capture the relevant physics Measure all important modeling data in the experiment Characteristics and imperfections of the experimental facility should be included in the model Jeremić, 3rd UJNR Workshop 4

5 Application Domain System complexity Application Domain Validation Domain Inference System Parameter Inference Based on physics or statistics Validation domain non convex aggregation of physical tests Physical experiments (NEES) provide for non overlapping validation domain Jeremić, 3rd UJNR Workshop 5

6 NEES SFSI Project Participants: Wood (UT), Anagnos (SHSU), Arduino (UW), Eberhard (UW), Fenves (UCB), Finholt (UM), Futrelle (NCSA), Grant (UK), Jeremić (UCD), Kramer (UW), Kutter (UCD), Matamoros (UK), McMullin (SHSU), Ramirez (PU), Rathje (UT), Saidi (UNR), Sanders (UNR), Stokoe (UT), Wilson (UCD). Jeremić, 3rd UJNR Workshop 6

7 Validation SFSI Experiments UC Davis centrifuge, single piles, bents, frames, scale 1/5 UT Austin, pile, pile column, bent, scale 1/4 UN Reno, frame (3 bents), scale 1/4 Purdue U., pier components, scale 1/ and 1/1 Jeremić, 3rd UJNR Workshop 7

8 The OpenSees Platform SFSI components Small deformation, single phase, linear and nonlinear elasticity and incremental template elasto plasticity (PY springs, D/3D solids) General, large deformation huperelasticity and hyperelasto plasticity for solids Full coupling of solid and fluid (u p U), (small deformations only at the moment) Elastic and inelastic beam column elements, elastic plate and plane stress elements (shells), small and large deformations Seismic input through the Domain Reduction Method Jeremić, 3rd UJNR Workshop 8

9 Template Elasto Plasticity Yield surfaces: von Mises, Drucker Prager, Rounded Mohr Coulomb, Cam Clay, Parabolic Leon, Plastic flow directions (potential surfaces): von Mises, Drucker Prager, Rounded Mohr Coulomb, Cam Clay, Manzari Dafalias, Parabolic Leon, Isotropic or kinematic hardening/softening linear and/or nonlinear isotropic hardening/softening linear or nonlinear kinematic hardening/softening Hierarchical database of models (by materials) Jeremić, 3rd UJNR Workshop 9

10 Template Examples q (kpa) ε v q (kpa) ε v ε a ε a ε a ε a 3 6 q (kpa) ε v q (kpa) ε v ε a ε a 5 ε a ε a q (kpa) 5 5 ε v q (kpa) 1 1 ε v ε a ε a ε a ε a Jeremić, 3rd UJNR Workshop 1

11 Single Pile in Layered Soils SAND φ = 37.1 o SAND φ = 37.1 o Depth (m) SOFT CLAY Cu = 1.7 kpa SAND φ = 37.1 o 4 4 Depth (m) SOFT CLAY Cu = 1.7 kpa SAND φ = 37.1 o Bending Moment (kn.m) Shear Force (kn) Lateral Resistance (kn/m) Bending Moment (kn.m) Shear Force (kn) Lateral Resistance (kn/m) Jeremić, 3rd UJNR Workshop 11

12 Pile Group Simulations Lateral Load Distribution in Each Pile Trail Row, Side Pile Third Row, Side Pile Second Row, Side Pile Lead Row, Side Pile Trail Row, Middle Pile Third Row, Middle Pile Second Row, Middle Pile Lead Row, Middle Pile Displacement at Pile Group Cap (cm) Plastic zone Load distribution Pile interactions (P-Y) Jeremić, 3rd UJNR Workshop 1

13 Full Coupling of Solid and Fluid (M s ) KijL (M f ) KijL (C 1 ) KijL (C ) KijL (C ) LjiK (C 3 ) KijL ū Lj p L Ū Lj ū Lj p L Ū Lj (K EP ) KijL (G 1 ) KiL (G 1 ) LjK (P ) KL (G ) LjK (G ) KiL ( f s ) Ki ( f f ) Ki + + ū Lj p L Ū Lj = Pore pressure (kpa) Solid Displacement (m) 1 x Top node m from top 3 4m from top 6m from top x 1 3 Fluid Displacement (m) (C 1 ) KijL = (C ) KijL = (C 3 ) KijL = Time (sec) Ω N u,u K n k 1 ij N u,u L dω Jeremić, 3rd UJNR Workshop 13

14 Seismic Input Domain Reduction Method, (Bielak et al. at CMU) Seismic motions and accelerations input at the layer of elements that encompass an elastic plastic zone (using SHAKE, Green s functions, Quake, SCEC...), non reflective boundaries Jeremić, 3rd UJNR Workshop 14

15 Verification SFSI Model. Acceleration (m/s ) Displacement (m) Time (s) Time (s) Jeremić, 3rd UJNR Workshop 15

16 SFSI: Stiff Soil Model Z(m) Max Z(m) Max Displacement (m) Displacement (m) Time (s) Time (s) Free Field SFSI Jeremić, 3rd UJNR Workshop 16

17 SFSI: Soft Soil Model Z(m) Z(m) Max Displacement (m) Displacement (m) Time (s) Time (s) Free Field SFSI Jeremić, 3rd UJNR Workshop 17

18 SFSI Model: Pile Column Behavior Displacemnt (m).1 Displacement (m) Time (s) Time (s) Stiff soil Soft soil Jeremić, 3rd UJNR Workshop 18

19 SFSI Model: Seismic Results Z(m) Max Z(m) Max Displacement (m) Displacement (m) Time (s) Time (s) Stiff soil Soft soil Jeremić, 3rd UJNR Workshop 19

20 I 88 SFSI Example Jeremic, 3rd UJNR Workshop

21 SFSI Advantageous.1 Fixed Model SFSI Model 6 x 1 6 Fixed Model SFSI model 4 Horizantal Displacement (m).5.5 Shear Force (N) Time (Sec) Displacement (m).5.1 Kobe JMA Jeremić, 3rd UJNR Workshop 1

22 SFSI Disadvantageous Horizantal Displacement (m) Fixed Model SFSI Model Shear Force (N) x Fixed Model SFSI model Time (Sec) Displacement (m) LP Corralitos Jeremić, 3rd UJNR Workshop

23 Conclusions SFSI problem requires close cooperation of experimentalists, modelers and simulators, Validation domain and Application domain to be bridged using simulation tools, One such simulation tool is OpenSees, the NEESgrid simulation platform The main OpenSees web site has links to documentation, examples, source code, executables, message board... Jeremić, 3rd UJNR Workshop 3