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IAN BUCKLEUNIVERSITY OF NEVADA RENO
PAC I F I C R IM FORUM EARTHQUAKE RES I L I ENCE NUCLEAR FAC I L I T I E S
UN IVERS I T Y OF CAL I FORN IA BERKE L E Y, JANUARY 23 ‐24 , 2017
Experimental validation of computational frameworks for soil‐structure‐interaction in nuclear facilities
Acknowledgements◦ Sponsor: Department of Energy / Lawrence Berkeley National Laboratory
◦As part of contract: A modern computational framework for the nonlinear analysis of nuclear facilities and systems
◦Major co‐investigators: ◦ David McCallen, Lawrence Berkeley National Laboratory◦ Boris Jeremic, University of California Davis◦ Arthur Rodgers, Lawrence Livermore National Laboratory
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Options for experimental validation of computational frameworks for soil‐structure‐interaction1. Geotechnical centrifuge: accurate soil modeling, but at a scale
where structural models are not realistic
2. Laminar soil box on shake table: more realistic structural models but soil properties are not modeled correctly
3. Case studies following major earthquakes: need more instrumented sites and structures
Conventional wisdom is to build as big‐a‐box (or centrifuge) as possible to minimize limitations of each approach.
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Large laminar soil box at E‐defense, Japan
E‐Defense Laminar Box: 6m (H) x 8m dia.
Inter‐laminate mechanism: THK LM bearing
Basic parameters1. Dedicated platform (vs. shared platform with existing shake
tables) 2. Laminar walls (vs. rigid walls)3. Biaxial (vs. uniaxial excitation)4. Circular (vs. square or rectangular)
Basic performance parameters1. Achievable soil strain: 2% 2. Dense soil: 120 pcf; assume upper bound soil strength3. Two configurations:
i. 24 ft diameter x 20 ft high (550 tons soil)ii. 24 ft diameter x 15 ft high (410 tons soil)
To design soil box and platen need to know… 1. Base shear and overturning moment on table platen for both
cases (550 ton and 410 ton boxes) at 2% strain
2. Complementary shears at interface of soil and box wall at 2%
3. Maximum forces and deformations in walls of box
4. Response of foundation (reactive mass) when box is at 2% strain
Using numerical simulations to provide answers1. DEEPsoil for 1D, nonlinear, soil‐column analyses for
preliminary design
2. LS‐DYNA for 2D and 3D nonlinear analyses of box and soil
3. Suite of 10, 2‐component ground motions taken from PEER database, for sites with similar seismogenic and geotechnicfeatures as found at LANL, and scaled for PGA as follows:
Scale Factor 1.0 2.0 3.0 4.0
PGA 0.26g 0.52 g 0.78 g 1.04 g
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Overview of LS‐DYNA models
10B Y10E Y 0.0010I Y 0.00 Y10K Y 0.33 Y10L Y 1.00 Y11I Y 0.00 Y Y Y11K Y 0.33 Y Y Y11L Y 1.00 Y Y Y11KK Y 0.33 Y Y 1.0011MM Y 0.85 Y Y 1.0011LL Y 1.00 Y Y 1.00
11MM2 Y 0.85 Y Y 1.00
2D ModelsPerfect Contact
Sliding at wall‐soil
Wall‐soil friction
GapBottom plate
Horiz const
Soil‐Plate
Examined different ground motions, contact conditions, mesh sizes, element formulations, effect of sliding, friction and gapping at the soil‐wall and soil‐base plate interfaces
Model 10I (μ=0) vs 10K (μ=0.33) vs 10L (μ=1) vs 10B (perfect contact)I
Forces in Walls
K
L
Increasing the friction coefficient increases the forces in the walls significantly. This coefficient is a key parameter. As the coefficient increases (10L) the model approaches the behavior of the perfect contact model (10B)
μ=0
μ=0.33
μ=1.0
Perfect
Reaction Forcesright wall
The forces in the soil‐box walls are out‐of‐phase during shaking due to the overturning moment
Model 10E vs 10I (μ=0) vs 10K (μ=0.33) vs 10L (μ=1) vs 10B (perfect contact)
0.000
5.000
10.000
15.000
20.000
25.000
30.000
35.000
40.000
1 2 3 4 5
Force (kips)
Models
Max base Shear
0.000
50.000
100.000
150.000
200.000
250.000
300.000
350.000
400.000
450.000
1 2 3 4 5
Mom
ent (kip‐ft)
Models
Max OTM
0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
1 2 3 4 5
Force (kips)
Models
Max Tension in Left Wall
0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
1 2 3 4 5
Force (kips)
Models
Max Tension in Right Wall
Sliding and gapping at the soil‐wall interface have little effect on the base shear, a slight effect on overturning moment (OTM) and a major effect on the axial forces in the walls
ModelNumber Name
1 10E2 10I
3 10K4 10L
6 10B
Model 10I (μ=0) vs 10B (perfect contact)Response histories of vertical reactions at base of the soil box
Small coefficients of friction at the soil‐wall interface allow soil to slide which introduces non‐uniform shear stresses in soil close to the walls indicating a significant boundary layer. To minimize the size of this layer and increase the area of uniform shear stresses, a larger coefficient of friction is required at both the soil‐wall and soil‐base plate interfaces
Model 10I (μ=0) vs 10B (perfect contact)Snapshot of vertical reactions at base of the soil box as a function of location:
Small coefficients of friction at the soil‐wall interface allow soil to slide which introduces non‐uniform shear stresses in soil close to the walls indicating a significant boundary layer. To minimize the size of this layer and increase the area of uniform shear stresses a larger coefficient of friction is required at both the soil‐wall and soil‐base plate interfaces
Sensitivity to input motions
Number Name1 4x Cerro 2372 4x El Centro 1803 4x Hector 0904 4x Landers 260
Ground Motion0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
1 2 3 4
Force (kips)
Ground motion
Base Shear
Model 10B_perfect contact
Model 11K_frictioncoefficient=0.33
200.00220.00240.00
260.00280.00300.00320.00340.00360.00380.00400.00
1 2 3 4
Mom
ent (kip‐ft)
Ground motion
OTMs
Model 10B_perfect contact
Model 11K_frictioncoefficient=0.33
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
1 2 3 4
Force (kips)
Ground motion
Max Tension in Left Wall
Model 10B_perfectcontact
Model 11K_frictioncoefficient=0.33
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
1 2 2 3 3 4 4
Force (kips)
Ground motion
Max Tension in Right Wall
Model 10B_perfectcontact
Model 11K_frictioncoefficient=0.33
3D models
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3D_1B Y3D_1I Y 0.00 Y3D_1K Y 0.33 Y3D_2I Y 0.00 Y Y 1.003D_2K Y 0.33 Y Y 1.003D_2M Y 0.85 Y Y 1.003D_3M Y 0.85 Y Y 1.003D_4M Y 0.85 Y Y 1.003D_5M Y 0.85 Y Y 1.003D_6M Y 0.85 Y Y 1.003D_7M Y 0.85 Y Y 1.003D_8M Y 0.85 Y Y 1.00
ModelsPerfect Contact
Sliding at wall‐soil
Wall‐soil friction
Gap ottom plaSoil‐Plate
Examined different ground motions, magnitudes, contact conditions, directions of shaking (uniaxial vs biaxial shaking), mesh sizes, element formulations, wall types
3D
Motion in X Motion in Y Biaxial Motion
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Effect of biaxial shaking –Model 3D_2M (μ=0.85)X
Y
LS‐DYNA 2D vs LS‐DYNA 3D: Wall Forces
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The 2D LS‐DYNA analyses gave maximum tensile forces in the walls that were up to 23% less than the forces obtained from the 3D analyses. This indicates the significance of 3D effects, which cannot be captured by simplified 2D analyses
2D Models Contact soil‐wall
Ground Motion
2D Max NetTension (kips/ft)
3D Max Net Tension (kips/ft) Ratio 2D/3D
11MM μ = 0.85 4x Cerro 237 12.6116.43 0.7715.10 0.84
10B perfect 4x Cerro 237 15.85 18.00 0.88
System Predicted Performance Against Requirements: 3X Motions, 550 tons soil
650 Ton 3X Motions
Max Abs Top Soil Disp (in)
Max Abs Base Shear (kips)
Max Soil Strain Any
Layer (%)Max OTM (kip‐ft)
Max Surface PGA (g)
Max Shake Table Disp X
Max Shake Table Disp Y
Min Shake Table Disp X
Min Shake Table Disp Y
Min Shake Table Vel X
Max Shake Table Vel Y
Min Shake Table Vel X
Min Shake Table Vel Y
Max Shake Table Force X
Max Shake Table Force Y
Min Shake Table Force X
Min Shake Table Force Y
Max Servo Valve X
Max Servo Valve Y
Min Servo Valve X
Min Servo Valve Y
Blowdown
Cerro 3.4/5.3 771/877 2.6/5.8 8471/8763 0.9/1.0 27 29 ‐22 ‐39 39 73 ‐49 ‐58 99 122 ‐96 ‐105 100 100 ‐100 ‐100 2884Denali 1.7/3.3 691/903 1.3/1.8 7701/8952 0.8/0.8 23 31 ‐35 ‐33 47 57 ‐44 ‐64 105 100 ‐106 ‐93 100 100 ‐100 ‐100 3863ElCen 3.5/5.5 878/925 2.2/3.8 8881/9770 0.8/0.9 36 33 ‐25 ‐31 56 64 ‐49 ‐55 103 114 ‐121 ‐136 100 100 ‐100 ‐100 3748Erzican 3.3/2.7 885/859 1.9/1.7 8513/8646 0.8/0.7 74 38 ‐31 ‐32 91 68 ‐105 ‐40 106 89 ‐121 ‐70 100 100 ‐100 ‐30 4395Gilroy 2.2/4.1 818/866 1.4/2.6 8410/9937 0.7/0.9 12 16 ‐15 ‐9 52 42 ‐56 ‐33 79 109 ‐106 ‐86 89 100 ‐100 ‐57 4795Gilroy2 4.0/3.3 892/838 2.1/1.6 9188/8452 0.8/0.8 42 26 ‐53 ‐23 70 42 ‐69 ‐56 138 113 ‐123 ‐83 100 100 ‐100 ‐64 4219Hector 1.9/4.9 709/850 1.1/4.2 7686/9435 0.7/1.0 18 48 ‐17 ‐42 45 75 ‐32 ‐79 91 125 ‐70 ‐89 100 100 ‐25 ‐100 3946Landers 1.0/0.6 546/543 0.6/0.4 6109/5849 0.7/0.6 16 16 ‐22 ‐9 31 20 ‐29 ‐25 72 65 ‐84 ‐63 23 15 ‐28 ‐19 4923Nishi 5.1/4.0 889/756 5.4/3.0 9357/8839 1.0/0.9 16 22 ‐16 ‐23 47 52 ‐36 ‐56 84 116 ‐78 ‐116 67 100 ‐30 ‐100 4351Takatori 5.1/2.8 832/733 3.4/3.4 9477/7446 0.9/0.9 37 80 ‐31 ‐83 60 106 ‐50 ‐78 92 105 ‐97 ‐86 60 100 ‐100 ‐100 2972
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Model 7 vs Model 8: Tall vs Short box
Model 7 Model 8 Height=20ft Height=15ft
Base Shear in X OTM in X Wall Forces
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Tall vs Short boxX
Y
Tall Box
Short Box
Tall (20ft) vs Short box (15ft)
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kips kips kip‐ft kip‐ft kips/ft3D_7Mxy 3 x Cerro 237 & 147 710 732 7733 8209 16.343D_8Mxy 3 x Cerro 237 & 147 574 614 4520 4921 8.99
Ratio squat/tall 0.81 0.84 0.58 0.60 0.55
Models Ground MotionMax Base Shear X
Max Base Shear Y
Max OTMx Max OTMyMax Net Tension
There are significant reductions of the OTMS and Wall Forces in the squat box
System Predicted Performance Against Requirements: 3X Motions, 410 tons soil, short
490 Ton Squat 3X Motions
Max Abs Top Soil Disp (in)
Max Abs Base Shear (kips)
Max Soil Strain Any
Layer (%)Max OTM (kip‐ft)
Max Surface PGA (g)
Max Shake Table Disp X
Max Shake Table Disp Y
Min Shake Table Disp X
Min Shake Table Disp Y
Min Shake Table Vel X
Max Shake Table Vel Y
Min Shake Table Vel X
Min Shake Table Vel Y
Max Shake Table Force X
Max Shake Table Force Y
Min Shake Table Force X
Min Shake Table Force Y
Max Servo Valve X
Max Servo Valve Y
Min Servo Valve X
Min Servo Valve Y
Blowdown
Cerro 3.2/4.2 671/739 3.0/5.6 5559/5206 1.0/1.1 27 29 ‐22 ‐39 39 73 ‐49 ‐58 84 104 ‐81 ‐88 59 100 ‐60 ‐100 2882Denali 1.3/2.2 611/731 1.4/1.6 4792/5148 0.9/0.9 23 31 ‐35 ‐33 47 57 ‐44 ‐64 91 84 ‐95 ‐83 48 45 ‐49 ‐93 3851ElCen 3.2/4.8 759/810 3.0/4.3 5318/6193 1.0/1.1 36 33 ‐25 ‐31 56 64 ‐49 ‐55 94 100 ‐112 ‐118 100 100 ‐100 ‐100 3727Erzican 2.7/1.7 686/680 2.1/1.5 5536/4771 0.9/0.8 74 38 ‐31 ‐32 91 68 ‐105 ‐40 92 75 ‐96 ‐62 100 93 ‐100 ‐30 4334Gilroy 1.9/3.9 685/769 1.7/2.9 4884/6064 0.8/1.0 12 16 ‐15 ‐9 52 42 ‐56 ‐33 73 96 ‐88 ‐77 66 100 ‐73 ‐37 4786Gilroy2 3.5/2.5 758/707 3.6/2.0 5408/4940 0.9/0.9 42 26 ‐53 ‐23 70 42 ‐69 ‐56 118 95 ‐111 ‐71 100 100 ‐100 ‐52 4214Hector 1.5/4.3 625/732 1.0/4.7 4723/5727 0.8/1.1 18 48 ‐17 ‐42 45 75 ‐32 ‐79 79 107 ‐71 ‐78 67 100 ‐23 ‐100 3928Landers 0.8/0.6 504/484 0.7/0.5 4011/3618 0.8/0.8 16 16 ‐22 ‐9 31 20 ‐29 ‐25 63 62 ‐79 ‐55 23 15 ‐23 ‐18 4926Nishi 4.6/3.3 769/669 6.2/3.3 5683/5330 1.0/1.1 16 22 ‐16 ‐23 47 52 ‐36 ‐56 71 105 ‐74 ‐104 43 100 ‐27 ‐100 4329Takatori 4.0/2.2 712/618 3.6/3.1 5689/4634 1.1/1.1 37 80 ‐31 ‐83 60 106 ‐50 ‐78 80 87 ‐81 ‐66 55 100 ‐40 ‐100 2948
Location of platen in Large‐Scale Structures Laboratory
150 ft
50 ft
Schematic of platen for 550/410‐ton biaxial soil box
Platen is 24 x 24 ftstiffened steel box supported on 8/12 hydrostatic bearing actuators and tie down struts.
Eight, 220 K actuators, (4 at each end of platen) +/‐ 10 inch dynamic stroke
Octagonal Box – (15 ft high, 21 frames, 75 tons)
Octagonal Box –Wall Section
560 elastomeric bearings◦ 32 bearings/frame for lower 14 frames◦ 16 bearings/frame for the top 7 frames
Additional acknowledgements◦UNR Design Team: ◦ Anastasia Bitsani, Graduate Student, numerical modeling ◦ Sherif Elfass, Research Faculty, soil box design◦ Denis Istrati, Graduate Student, numerical modeling◦ Patrick Laplace, Research Faculty, platen design◦ Ramin Motamed, Academic Faculty, geotechnical modeling◦ Raj Siddharthan, Academic Faculty, geotechnical modeling
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Thank you!