Geotechnical and SSI Simulations

Transcription

1 Geotechnical and SSI Simulations Ahmed Elgamal Jinchi Lu Zhaohui Yang 1 Yuyi Zhang, Joel P. Conte, Zhaohui Yang, Ahmed Elgamal, Jacobo Bielak, and Gabriel Acero, Two- Dimensional Nonlinear Earthquake Response Analysis of a Bridge-Foundation-Ground System, Earthquake Spectra, Volume 24, No. 2, pages , May 2008, Earthquake Engineering Research Institute 2 1

2 2-D Finite Element Model in OpenSees Prof. Joel Conte, Joint Research Plane strain condition 11,000 nodes and 10,900 elements; 20,000 DOF s 370 beam-column elements 9,900 quadrilateral soil elements 590 zero-length elements 3 Superstructure Joints Abutment joints: Zero-length elements with gap-hook material Superstructure ZeroLength Element ZeroLength Element Beam Beam 1/2 Expanded Joint Filler All Around Shear Key 5 #4 Rebars per Key Cap Beam Gap & Hook Column Gap & Hook Expansion joints: Zero-length elements with gap-hook material Superstructure ZeroLength Element ZeroLength Element Beam Beam 1/2 Expanded Joint Filler All Around Shear Key 5 #4 Rebars per Key Cap Beam Gap & Hook Column Gap & Hook 4 2

3 OpenSees 3D FE Model 30,237 nodes Three-Dimensional Seismic Response of Humboldt Bay Bridge-Foundation-Ground System, A. Elgamal, L. Yan, Z. Yang, and J. P. Conte, Journal of Structural Engineering, Vol. 134, No. 7, July 1, Transverse and Longitudinal Response 3D Spatial Configuration Abutments Pile Foundations Ground 1,140/280 linear/nonlinear beam-column elements 81 linear shell elements 23,556 solid brick elements 1,806 zero-length elements 5 Piers and Pile Groups (Fiber Discretization of Pier and Pile Cross-Sections) (Prof. P. Fillippou) Kent-Scott-Park model Bilinear 6 3

4 Definition of Seismic Excitation (Engineering Seismology) (1) Rock outcrop motion Shear Wave Velocity (m/s) Deconvolution Using Shake91 Rock profile (3) Incident motion at FE model base Propagation Using Shake91 Soil profile Depth (m) Model Idealization Measured (2) Incident motion at the top of bedrock (2) 240 σ 1 σ 1 = σ 2 = σ 3 Stage I Stage II σ 3 Stiff spring Equivalent supporting force σ 2 Dashpot Equivalent earthquake force Note: Tied node condition on lateral A. Elgamal boundaries Sept 2008 (shear beam concept) 7 Elevation and Plan View of Residual Deformation (Scaling Factor = 50)

5 Numerical Analysis Three-Dimensional Seismic Response of Humboldt Bay Bridge-Foundation-Ground System, A. Elgamal, L. Yan, Z. Yang, and J. P. Conte, Journal of Structural Engineering, Vol. 134, No. 7, July 1, Permanent Deformation of Bridge, Foundations, and Abutments Original position Final position with residual deformation Left abutment #1 Pier & pile group #2 Pier & pile group #3 Pier & pile group #4 Pier & pile group #5 Pier & pile group #6 Pier & pile group #7 Pier & pile group #8 Pier & pile group Right abutment (a) Elevation view (exaggerated scale by a factor of 50) Final position with residual deformation (b) Plan view (exaggerated scale by a factor of 150) Original position 10 5

6 Shallow Foundation Settlement due to Liquefaction Foundation settlement time histories Untreated case Vertical displacement (m) Medium Sand (LMS) Dense Gravel (LDG) Stone Column (LSC) Time (sec) Treated by compaction and high permeability Acceleration (g) Time (sec) Treated by stone columns (Scale factor for deformed meshes: 10) 11 US-Japan Cooperative Research ( ) 12 6

7 1.8m high, UCSD Shake table tests (Prof. Dobry, RPI Test Setup Laminar container provided by Prof. Scott Ashford, UCSD 13 Experiment Preparation 14 7

8 9/14/2008 UCSD Shake table test A. Elgamal Sept NIED, Tsukuba, Japan Shaking Table Tests: US-Japan Research (NSF, NIED, PEER, CALTRANS) 5m height: Liquefaction-Induced lateral Spreading Effects on Piles (NIED, Tsukuba) Professor Kohji Tokimatsu,A.Dr. Masayoshi Elgamal Sept 2008Sato, and Dr. Akio Abe 16 8

9 Before After 1m of Lateral Spreading ( > 3 pile diameters) NIED, Tsukuba, Japan

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13 Gravel Drain/Stone column Ground Modification 25 User Interface for Pile-ground systems a) Isometric view b) Pile head close-up Finite element mesh A. Elgamal for Sept the x3 pile group

14 OpenSees Computations through Graphical Interface OpenSeesPL 0.3 Pile head deflection (in) x3 pile group Single pile Spacing (xd) Pile group displacement of the 3x3 pile group (for different spacing) and the single pile under lateral loading. 27 OpenSees Computations through Graphical Interface OpenSeesPL Spacing = 2D Spacing A. Elgamal = 3D Sept

15 9/14/2008 OpenSees Computations through Graphical Interface OpenSeesPL Spacing = 4D Spacing = 5D A. Elgamal Sept OpenSees Computations through Graphical Interface OpenSeesPL Spacing = 6D Spacing = 7D A. Elgamal Sept

16 OpenSees Computations through Graphical Interface OpenSeesPL Spacing = 8D 31 OpenSeesPL Manual Examples Chapter 6 Examples 6.1 Example 1: Linear Pile in Rigid Ground 6.2 Example 2: Linear Pile in Loose Sand 6.3 Example 3: Linear Pile in Medium Sand 6.4 Example 4: Nonlinear Pile in Linear Soil 6.5 Example 5: Saturated Medium Sand 6.6 Example 6: Stone Columns 6.7 Example 7: Pile in Sloping Ground Appendix A Benchmark Linear Finite Element Analysis of Laterally Loaded Single Pile Using OpenSees & Comparison with Analytical Solution Appendix B Finite Element Analysis of Arkansas Test Series Pile #2 Using Opensees (with LPILE Comparison) Appendix C Finite Element Analysis of Standard CalTrans 16" CIDH Pile Using Opensees for General Comparison with LPILE (with Default P-Y Multiplier = 1.0) Appendix D Finite Element Analysis of Caltrans 42" CIDH Pile Using OpenSees for General Comparison with LPILE (with Default P-Y Multiplier = 1.0) Appendix E Finite Element Analysis of Standard CalTrans 16" CIDH Pile Subjected to Axial Load Appendix F Moment-Curvature Analysis of Circular Nonlinear RC Beam (Fiber Section) 32 16

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