1. The Alaskan Way Viaduct Steve Kramer University of Washington Seattle, Washington

2. The Alaskan Way Viaduct Steve Kramer University of Washington Seattle, Washington (The interesting stuff, not the structural stuff)

3. Alaskan Way Viaduct 2.2 miles long 86,000 vehicles per day North of Yesler Designed by City of Seattle Constructed in 1950 South of Yesler Designed by Washington State DOH Constructed in 1956

4. Alaskan Way Viaduct

5. © 1993 DeLorme Mapping Seattle Yesler Terrace Elliott Bay 99 Harborview Hospital U S Marina Hospital Mason Hospital Union Depot King Street Station Seattle University 1ST 4TH ALASKAN WAY BOREN E MADISON RAINIER AVE S S 1ST STEWART YESLER WAY I-5 RAMP I-90 © 1993 DeLorme Mapping Seattle section WSDOT section Alaskan Way Viaduct

7. Seattle section WSDOT section

8. Alaskan Way Viaduct Seattle Section

9. Alaskan Way Viaduct WSDOT Section

10. Seismic Vulnerability Concerns Loma Prieta earthquake M=7.1 100 km south of Oakland Cypress Structure Highway 17 in Oakland Double-deck reinforced concrete structure Similar age Similar design requirements Pile supported due to soft surficial soils

11. Cypress Structure

13. Alaskan Way Viaduct Investigations 1990 WSDOT internal review 1991-92UW review 1993-95 UW/WSDOT investigation 1995-96WSDOT seawall investigation

14. UW / WSDOT Investigation WSDOT Seawall Investigation Structural Engineering Aspects Geotechnical Engineering Aspects Seawall performance Effects on AWV Remediation strategies

15. Geotechnical Engineering Investigation Site characterization Seismic hazard analysis Ground response analyses Foundation response characteristics Evaluation of liquefaction hazards

16. Site Characterization Review of historical records Review of previous subsurface investigations Supplemental subsurface investigations ­ ­ SPT ­ ­ CPT ­ ­ Seismic cone ­ ­ Downhole seismic

17. Seattle, 1888 Historical Records

18. Seattle, 1884 Historical Records Lake Washington Yesler I-5

19. Looking NW from Beacon Hill

20. Looking north along waterfront

21. Looking east from Elliot Bay

22. Seattle Regrading Activities

23. Tideflats, 1896 Tideflat Reclamation

25. Railroad Avenue - 1920s

27. Seattle Seawall 12,000 lb/ft lateral thrust Four different wall types - - Timber pile-supported relieving platform (2) - - Pile-supported concrete wall - - Fill and rip rap wall Total cost: $1.4 million

28. Type B Seawall Section

29. Precast Section Master Pile Timber Relieving Platform Batter Piles (12) Vertical Piles (6)

30. Pile/Platform Connection

31. Seawall Construction

33. Fill and Rip Rap Wall Section

34. Alaskan Way Viaduct History - - Originally intended as downtown bypass - - Design began in 1948, bids opened 1949 - - Seattle section opened April 4, 1953 - - WSDOT section opened Sept 3, 1959 - - Seneca Street off-ramp opened 1961 - - Columbia Street on-ramp opened 1966 Facts - - 7,600 ft long - - 58,867 yards of concrete, 7,460 tons of rebar - - 171,410 ft of piling

35. 36 ft 22 ft 70 ft Typical Elevation (WSDOT Section) 57 ft

36. 36 ft 22 ft 47 ft Typical Interior Bent (WSDOT Section)

37. Foundations WSDOT Section Seattle Section

38. 2’ 2.5’ Foundations Seattle Section WSDOT Section 17’ 13.5’ 12’ 3.5’

39. Seattle Section WSDOT Section Originally intended to use only H-piles Contractor requested change Steel piles - 48 tons All other piles - 40 tons

40. S. Massachusetts St. Columbia St. University St. Yesler Way S. Royal Brougham Way Blanchard SubsurfaceData Stewart St. 50 shallow borings by SED in 1948 17 deep borings by WSDOH in mid-1950s Various borings by others 8 borings with SPT 16 CPT soundings with seismic cone 2 deep borings with downhole seismic

41. 100 50 0 -50 -100 -150 Elevaion (ft) Elevation (ft) 100 0 50 -50 -100 -150 Waterfront Fill Tideflat Deposit Till 1000 ft Blanchard Stewart University Yesler Massachusetts Royal Brougham Subsurface Profile

42. Standard Penetration Resistance (blows/ft) Depth (ft) Uncorrected SPT Resistance

43. Uncorrected CPT Tip Resistance Depth (ft) Cone Penetration Tip Resistance (tsf)

44. 0 100 150 200 250 50 01000 20003000 Shear Wave Velocity (ft/sec) Depth Below Top of Till (ft) Federal Building B-1 B-2 Till Stiffness Average

45. Input Motions PSHA (10% in 50 yrs = 475-year return period) - - Peak acceleration - - Spectral velocities - - Bracketed duration Design-level response spectrum Quasi-synthetic time histories Deconvolution to produce 3 “bedrock” motions Acceleration (g) Time (sec)

46. Ground Response Analysis Equivalent linear analyses (SHAKE) Nonlinear, effective stress analyses (TESS, DESRA) Numerous soil profiles

47. 0 20 30 40 50 10 Time (sec) 0.6 0.0 -0.6 0.6 0.0 -0.6 0.6 0.0 -0.6 Acceleration (g) 10 ft soft soil 50 ft soft soil 100 ft soft soil Ground Surface Motions

48. 0.0 Period (sec) 1.0 2.0 3.0 4.0 5.0 0.0 1.0 2.0 0.5 1.5 2.5 S (g) a Ground Surface Response Spectra 10 ft soft soil 50 ft soft soil 100 ft soft soil

49. Waterfront Fill Tideflat Deposit Till a max 0.0 0.5 Peak Accelerations

50. Liquefaction Susceptibility Historical evidence - - Sand boils in 1949 and 1965 - - Broken pipes in 1949 and 1965 - - Lateral movements in 1965 Construction techniques - - Hydraulic filling - - Dumping through water Previous investigations - - Mabey and Youd (1991) - - Grant et al. (1992)

51. Scenario Earthquake #1 Scenario Earthquake #2 M 7.5 a max 0.30 g 0.15 g Displacement (in.) >100 14 - 100 84 - 100 6 - 48 45 - 84 2 - 12 10 - 45 0 - 4 Little liquefaction susceptibility but in areas with steep slopes. Liquefaction is unlikely, but if it were to occur, large displacements are possible. No displacement likely due to liquefaction. Mabey and Youd (1991)

52. Depth (ft) (N ) 1 60 (N ) 1 60 required to prevent liquefaction Liquefaction Evaluation Standard Penetration Test

53. (N ) 1 60 Depth (ft) (N ) 1 60 required to prevent liquefaction Liquefaction Evaluation Standard Penetration Test

54. FS L Depth (ft) SPT-Based Factor of Safety

55. Depth (ft) (q ) c 1 (q ) c 1 required to prevent liquefaction (tsf) Liquefaction Evaluation Cone Penetration Test

56. Depth (ft) (q ) c 1 (tsf) Liquefaction Evaluation Cone Penetration Test (q ) c 1 required to prevent liquefaction

57. Depth (ft) (N ) 1 60 Design-level ground motion Liquefaction Evaluation Comparison with 1965 observations

58. Depth (ft) (N ) 1 60 Design-level ground motion 1965 ground motion Liquefaction Evaluation Comparison with 1965 observations

59. (N ) 1 60 Depth (ft) Design-level ground motion Liquefaction Evaluation Comparison with 1965 observations

60. (N ) 1 60 Depth (ft) Design-level ground motion 1965 ground motion Liquefaction Evaluation Comparison with 1965 observations

61. FS L Depth (ft) SPT-Based Factor of Safety 1965 ground motion

62. Effects of Liquefaction Sand boils - expected over most of length Post-earthquake settlement - - Up to 1” in fill above water table - - Up to 25” in soft, saturated soils Vertical pile movement - - Tip capacity reached at r = 0.6 - - Tips of southernmost piles in liquefiable soil Lateral pile movement - - Depends on lateral soil movement - - 10”-12” expected to cause bending failure - - Lateral soil movement depends on seawall movement u All movements variable due to variability of soil profile

63. Seawall Investigation Transverse profile characterization - - 5 additional borings (2 offshore) - - 3 additional CPT soundings Seawall structure characterization - - Member sizes - - Member properties - - Connection strengths Computational model - - Soil - - Seawall - - Soil-seawall interaction Estimation of permanent deformations due to liquefaction FLAC

64. FLAC Fast Lagrangian Analysis of Continua Explicit finite difference code Large-strain capabilities Several soil constitutive models Structural elements (beams, piles, cables) Interface elements (normal and shear) Coupled stress-deformation and flow capabilities Incremental construction modeling Graphical display of results Dynamic option Creep option FISH programming language

65. Alaskan Way Viaduct Type B Wall Model Entire Section

66. Alaskan Way Viaduct Type B Wall Model Entire Section 3400 soil elements 610 structural elements

67. Type B Wall Model

68. Precast Section Master Pile Timber Relieving Platform Batter Piles (12) Vertical Piles (6) Type B Wall Model

69. Modeling Approach Strain Stress G G f i Strain due to softening Primary effects of liquefaction - - Reduction of soil strength - - Reduction of soil stiffness Stiffness reduction approach 1. Analyze with pre- liquefaction properties 2. Analyze with post- liquefaction properties 3. Subtract pre- liquefaction displacements from post- liquefaction displacements

70. Displacements Maximum Displ = 0.71 ft

71. Deformed Shape Deformations magnified by factor of 5

72. Bending Moments

73. Type B Wall Before liquefaction

74. Type B Wall During liquefaction

75. Type B Wall After liquefaction

76. Fill and Rip Rap Wall Before liquefaction

77. Fill and Rip Rap Wall During liquefaction

78. Fill and Rip Rap Wall After liquefaction

79. Columbia St. Madison St. University St. S. Washington St. Zones of Large Lateral Movements