Youssef Hashash Associate Professor In collaboration with Duhee

Youssef Hashash Associate Professor In collaboration with Duhee Park Post-Doctoral Research Assistant University of Illinois at Urbana-Champaign PEER 2 G 02 First Meeting September 21, 2004

DEEPSOIL n 1 -D Site response analysis code n Nonlinear / Equivalent linear analysis n User interface 2 Hashash and Park

Motivation for Development n Thick soil deposits such as those encountered in the Mississippi Embayment in Mid-America n Sponsored in part by Mid-America Earthquake Center n References: q q Park, D. and Y. M. A. Hashash (2004). "Soil damping formulation in nonlinear time domain site response analysis. " Journal of Earthquake Engineering 8(2): 249 -274. Hashash, Y. M. A. , and Park, D. (2002). "Viscous damping formulation and high frequency motion propagation in nonlinear site response analysis. " Soil Dynamics and Earthquake Engineering, 22(7), pp. 611 -624. Hashash, Y. M. A. , and Park, D. (2001). "Non-linear one-dimensional seismic ground motion propagation in the Mississippi embayment. " Engineering Geology, 62(1 -3), 185206. Park, D. (2003). ESTIMATION OF NON-LINEAR SEISMIC SITE EFFECTS FOR DEEP DEPOSITS OF THE MISSISSIPPI EMBAYMENT. Department of Civil and Environmental Engineering. Urbana, University of Illinois at Urbana-Champaign: 337 p. 3 Hashash and Park

Outline n Features of DEEPSOIL q q q Nonlinear n Numerical Model n User Interface Equivalent Linear n Numerical Model n User Interface Additional Features of the User Interface 4 Hashash and Park

Nonlinear (NL) Features n n n Soil Model Viscous Damping Formulation Dynamic Integration Scheme Increased Numerical Accuracy User Interface 5 Hashash and Park

NL Feature – Soil Model n Extended Modified Hyperbolic Model q q Based on Modified Hyperbolic Model (Matasovic, 1993) Confining pressure dependent Modified Hyperbolic Model 6 Hashash and Park

NL Feature – Soil Model G / Gmax & Confinement Damping & Confinement 7 Hashash and Park

NL Feature– Viscous Damping Formulation Viscous damping formulation [C] ØSimplified Rayleigh damping formulation ØFull Rayleigh damping formulation Conventional Selection of Frequencies/Modes (CRF) Proposed Selection (RF) ØExtended Rayleigh damping formulation (ERF) 8 Hashash and Park

Feature 2 – Viscous Damping Formulation Target Damping Ratio Fig 3 -1 Page 68 9 Hashash and Park

Feature 2 – Viscous Damping Formulation Target Damping Ratio Selection of frequencies/modes for Full Rayleigh damping formulation CRF (Conventional RF) : fm = 1 st mode of soil column, fn=dominant period of input motion RF (Proposed RF) : fm and fn chosen from transfer function of soil column and frequency content of input motion An iterative process 10 Hashash and Park

NL Feature– Viscous Damping Formulation Target Damping Ratio 11 Hashash and Park

Numerical Implementation Cyclic soil response model Input ground motion Multi-degree of freedom lumped parameter model 12 Hashash and Park

Nonlinear (NL) Integration Scheme n Newmark Beta Method (Average acceleration method: =1/4, =1/2 q Implicit Method q Unconditionally stable q No numerical damping 13 Hashash and Park

NL Feature – Viscous Damping Formulation n RF – Conventional Approach q Use first mode of soil column and a higher mode or predominant period of ground motion 14 Hashash and Park

NL Feature – Viscous Damping Formulation n RF/ERF Proposed Guideline q q Use iterative procedure to obtain best match with frequency domain solution Dependent on soil column Dependent on input motion ERF: Computationally expensive 15 Hashash and Park

NL Feature – Viscous Damping Formulation n Variable [C] Matrix q Updates stiffness in the RF formulation 16 Hashash and Park

NLFixed Feature – Increased Numerical Accuracy Sub-incrementation Scheme: Independent of strain level Flexible Sub-incrementation Scheme: depends on strain level Input Motion Station JMA NS Kobe Earthquake, PGA = 0. 82 g 17 Hashash and Park

NL User Interface – Input Soil Profile 18 Hashash and Park

NL User Interface – Input Soil Profile 19 Hashash and Park

NL User Interface – Soil Model Parameter Selection 20 Hashash and Park

NL User Interface – Viscous Damping Formulation 300 m ME Profile M=8, R=32 km Motion 21 Hashash and Park

NL User Interface – Viscous Damping Formulation 22 Hashash and Park

NL User Interface – Viscous Damping Formulation 23 Hashash and Park

NL User Interface – Viscous Damping Formulation 24 Hashash and Park

NL User Interface – Numerical Accuracy Control 25 Hashash and Park

NL User Interface – Output 26 Hashash and Park

Equivalent linear (EQL) Features n n 3 Types of Complex shear modulus q Frequency independent (Kramer, 1996) q Frequency dependent (Udaka, 1975) q Simplified (Kramer, 1996) No limitation on q q q number of layers number of materials number of motion data points 27 Hashash and Park

EQL Features (SHAKE, use with care) 28 Hashash and Park

Additional Features 29 Hashash and Park

Verification of DEEPSOIL Loma Prieta Earthquake, M = 7. 1, October 19, 1989 -Significance of viscous damping in DEEPSOIL (Strong Motion & non-linear material) -Soil column: ~88 m 30 Hashash and Park

Verification of DEEPSOIL E-W N-S 31 Hashash and Park

Nonlinear Soil Model Parameters n n No Fixed Parameter Selected to match various reference dynamic curves (G/Gmax and damping curves) 32 Hashash and Park

NL Soil Model Parameters – Mississippi Embayment (ME) ME study ME EPRI 1. 4 0. 85 s 0. 8 0. 9 (a) Reference strain @ ’ref 0. 163 0. 07 ’ref 0. 18 b 0. 63 0. 4 33 c Varies with depth d 0 0 Hashash and Park

NL Soil Model Parameters - EPRI ME study ME EPRI 1. 4 0. 85 s 0. 8 0. 9 (a) Reference strain @ ’ref 0. 163 0. 07 ’ref 0. 18 b 0. 63 0. 4 34 c Varies with depth d 0 0 Hashash and Park

NL Soil Model Parameters-Treasure Island 35 Young Bay Mud Old Bay Mud 0. 8 0. 9 s 0. 8 0. 7 (a) Referenc e strain @ ’ref 0. 17 0. 065 ’ref N/A b 0. 0 c 1. 5 d 0 0. 0 Hashash and Park