2005 OpenSees Symposium OpenSees

Transcription

1 P E E R 25 OpenSees Symposium OpenSees Geotechnical Capabilities and Applications Dr. Liangcai He Prof. Ahmed Elgamal Dr. Zhaohui Yang Mr. James L. Yan Mr. Jinchi Lu (U.C. San Diego)

2 Soil Materials and Elements in OpenSees ( 2D/3D solid-fluid fully coupled elements for simulating pore pressure generation/redistribution/dissipation (based on the u-p formulation of Zienkiewitz and Chan). 3D soil material models for simulating drained/undrained cyclic behavior, including liquefaction and liquefaction-induced permanent ground deformation. For user convenience, predefined soil material parameters are available for a wide range of soil types. Manual pages are available at OpenSees web site (under Model- Building Objects section) 25 examples are available at

3 Solid-Fluid Fully Coupled Elements Implemented in OpenSees ( Plane-strain elements 9_4_QuadUP quadup 3D elements 2_8_BrickUP brickup

4 Pressure Dependent Soil Model (for Sands and Silts) Multi-surface, non-associative plasticity model, incorporating soil dilatancy and liquefaction effects.

5 Pressure Independent Soil Model (for Clays and Silts) Multi-surface, associative plasticity model. τ γ τ Failure surface P'

6 Undrained Material Model Coupled with sand/clay materials above to simulate undrained soil response (e.g., soil below ground water table).

7 References for Soil Models and Fully-Coupled Elements Ahmed Elgamal, Zhaohui Yang, Ender Parra, and Ahmed Ragheb (23). "Modeling of Cyclic Mobility in Saturated Cohesionless Soils, Int. J. Plasticity, 9(6), Ahmed Elgamal, Zhaohui Yang, and Ender Parra (22). "Computational Modeling of Cyclic Mobility and Post-Liquefaction Site Response," Soil Dynamics and Earthquake Engineering, 22(4), Zhaohui Yang and Ahmed Elgamal (22). "Influence of Permeability on Liquefaction-Induced Shear Deformation," J. Engineering Mechanics, ASCE, 28(7), Zhaohui Yang, Ahmed Elgamal, and Ender Parra (23). "A Computational Model for Liquefaction and Associated Shear Deformation," J. Geotechnical and Geoenvironmental Engineering, ASCE, 29(2), 927.

8 OpenSees analysis of bridge-ground interaction effects Prof. J. Conte, Mr. Y. Zhang, Mr. G. Acero (Structural) Prof. A. Elgamal, Dr. Z. Yang, Mr. James Yan (Geotechnical)

9 OpenSees Model of Humboldt Bay Bridge (UCSD) Water Table

10 Soil Materials Sand model response 2 Shear stress (kpa) Shear strain (%) Clay model response 6 4 Shear stress (kpa) Shear strain (%)

11 Concrete Piers (Conte, Acero, Zhang) Force-based nonlinear beam-column element with fiber cross section Stress Stress Stress Stress Strain Strain Concrete: Kent-Scott-Park Model Steel: Bilinear Model 2 x 4 x 5 Unconfined concrete Confined concrete Moment [k-in] Moment (kips-in) Moment (kips-in) Reinforcing Steel Curvature (/in) x -3 Monotonic Pushover (Single Column on Fixed Base) Curvature (/in) x -3 Cyclic Pushover (Single Column on Fixed Base)

12 Precast, Prestressed Pile Groups (Conte, Acero, Zhang) OpenSees Model Response Nonlinear Fiber Beam-Column Element Unconfined concrete Confined concrete Reinforcing steel

13 Main Deformation Pattern: Settlement and Lateral Movement of Abutments

14 Moment-Curvature Response at Column Base (Conte, Acero, Zhang) x 4 x 4 Base Section of Column Base Section of Column x 4 x 4 Base Section of Column 2 Base Section of Column 2 x 4 x 4 Base Section of Column 3 Base Section of Column 3 x 4 x 4 Base Section of Column 4 Base Section of Column Moment [kn-m] Moment (KN*m) Moment (KN*m) Moment [kn-m] Moment (KN*m) Moment (KN*m) Moment [kn-m] Moment (KN*m) Moment (KN*m) Moment [kn-m] Moment (KN*m) Moment (KN*m) Curvature -.2 (/m) Curvature -.2 (/m) Curvature -.2 (/m) Curvature -.2 (/m).2.4 Curvature (/m) Curvature (/m) Curvature (/m) Curvature (/m) Column Column 2 Column 3 Column 4 x 4 x 4 Base Section of Column 5 Base Section of Column 5 x 4 x 4 Base Section of Column 6 Base Section of Column 6 x 4 x 4 Base Section of Column 7 Base Section of Column 7 x 4 x 4 Base Section of Column 8 Base Section of Column 8 Moment [kn-m] Moment (KN*m) Moment (KN*m) Moment Moment (KN*m) [kn-m] Moment (KN*m) Moment (KN*m) [kn-m] Moment (KN*m) Moment [kn-m] Moment (KN*m) Moment (KN*m) Curvature -.2 (/m) Curvature -.2 (/m) Curvature -.2 (/m) Curvature -.2 (/m).2.4 Curvature (/m) Curvature (/m) Curvature (/m) Curvature (/m) Column 5 Column 6 Column 7 Column 8

15 Soil Shear Stress - Strain Response 5 5 Soil Element 245 Soil Element Soil Element 276 Soil Element Soil Element 35 Soil Element Soil Element 9 Soil Element 9 Shear Stress [kpa] Shear Stress (KPa) Shear Stress (KPa) Shear Stress [kpa] Shear Stress (KPa) Shear Stress (KPa) Shear Stress [kpa] Shear Stress (KPa) Shear Stress (KPa) Shear Stress [kpa] Shear Stress (KPa) Shear Stress (KPa) Shear Strain Shear Strain Shear Strain 5 x -3 5 Shear Strain x Shear Strain Shear Strain Shear Strain.5. Shear Strain

16 3D OpenSees Bridge Model 26,863 elements, 3,237 nodes, and, equations Soil Standard 8-node brick element with pressure-independent nonlinear soil material Boundary: Lysmer Transmitting Boundary

17 Defining Spatially Varying Ground Motion using Domain Reduction Method (Bielak et al. 23) Vertical wave 3 o Inclined wave

18 References for OpenSees Bridge-Ground Interaction Analyses Yuyi Zhang, Gabriel Acero, Joel Conte, Zhaohui Yang and Ahmed Elgamal (24). Seismic Reliability Assessment of a Bridge Ground System, Proceedings of 3th World Conference on Earthquake Engineering, Vancouver, B.C., Canada, August - 6, Paper No Zhaohui Yang, Liangcai He, Jacobo Bielak, Yuyi Zhang, Ahmed Elgamal, Joel Conte. (23). "Nonlinear Seismic Response of a Bridge Site Subjected to Spatially Varying Ground Motion," Proc., 6th ASCE Engineering Mechanics Conference, July 68, Univ. of Washington, Seattle, WA. Yuyi Zhang, Zhaohui Yang, Jacobo Bielak, Joel P. Conte, and Ahmed Elgamal. (23). "Treatment of Seismic Input and Boundary Conditions in Nonlinear Seismic Analysis of a Bridge Ground System," Proc., 6th ASCE Engineering Mechanics Conference, July 68, Univ. of Washington, Seattle, WA. Joel P. Conte, Ahmed Elgamal, Zhaohui Yang, Yuyi Zhang, Gabriel Acero, and Frieder Seible (22). "Nonlinear Seismic Analysis of a Bridge Ground System," (CD-ROM), Proceedings, 5th ASCE Engineering Mechanics Conference, Columbia Univ., New York, June 2-5, A. Smyth (Ed.).

19 OpenSees analysis of liquefaction-induced lateral spreading effects on piles (PhD Thesis, Dr. Liangcai He, UCSD, 25)

20 Shake-table and Soil Box used in the Experiments NIED, Japan

21 5m high,.3m diameter, Japan shake table tests

22 3D Finite Element Study Soil was modeled using BrickUP (8-node) element with pressure-dependent soil material. Piles were modeled using NonlinearBeamColumn with bilinear moment-curvature property.

23 Deformed Mesh at s

24 Pore pressure at s

25 .5.5 Free field displacement profile (w/ or w/o piles) Depth (m) Experimental Numerical without Pile Numerical with pile Groud lateral displacement (m)

26 Free-field excess pore pressure PWP GW 6 (.5 m depth) Experimental Numerical PWP GW (.5 m depth) Excess pore pressure (kpa) PWP GW 4 (2.5 m depth) PWP GW 8 (3.5 m depth) PWP GW 2 (4.5 m depth) Pile moment (kn m) Time (s)

27 Free-field displacement.4 Experimental Numerical DSB 2 ( m depth).2.4 DSB 3 (.5 m depth).2 Lateral Displacement (m).4.2 DSB 4 (. m depth).4 DSB 5 (.5 m depth) Time (s)

28 Free-field acceleration.35 Experimental Numerical AGE 3 (Surface) AGE 4 (.327 m depth).35 Lateral Acceleration (g) AGE 6 (.827 m depth) AGE 8 (.327 m depth) AGE (.827 m depth) Time (s)

29 .35 Free-field acceleration (cont d) Experimental Numerical AGW 4 (2.575 m depth) AGW 6 (3.75 m depth).35 Lateral Acceleration (g) AGW 8 (3.575 m depth) AGW 2 (4.75 m depth) AGW 22 (4.575 m depth) Time (s)

30 Moment (Kn m) Moment (Kn m) Maximum pile moment response (pile base) Time (s) Pile yielded Right Side Stiff pile Left Side Flexible pile Time (s)

31 Pile head displacement Lateral displacement (m) Right side stiff pile Experimental Numerical Left side flexible pile.4.3 M.2. Pile yielded θ Time (s)