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UNBONDED POST-TENSIONING: SEISMIC APPLICATIONS IN CONCRETE STRUCTURAL WALLS

UNBONDED POST-TENSIONING: SEISMIC APPLICATIONS IN CONCRETE STRUCTURAL WALLS. Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A. Tokyo Institute of Technology Yokohama, Japan August 16, 2000. ELEVATION. anchorage. wall panel. unbonded PT steel. horizontal joint.

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UNBONDED POST-TENSIONING: SEISMIC APPLICATIONS IN CONCRETE STRUCTURAL WALLS

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  1. UNBONDED POST-TENSIONING: SEISMIC APPLICATIONS IN CONCRETESTRUCTURAL WALLS Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A Tokyo Institute of Technology Yokohama, Japan August 16, 2000

  2. ELEVATION anchorage wall panel unbonded PT steel horizontal joint spiral reinforcement foundation

  3. LATERAL DISPLACEMENT precast wall gap opening shear slip

  4. BEHAVIOR UNDER LATERAL LOAD base shear, kips (kN) 800 (3558) concrete crushing (failure) PT bar yielding (flexural capacity) effective linear limit (softening) gap opening (decompression) roof drift, % 0 1 2

  5. BONDED VERSUS UNBONDED BEHAVIOR D D N H bonded wall unbonded wall

  6. HYSTERETIC BEHAVIOR base shear, kips (kN) 800 (3558) roof drift, % 1 -2 2 -1 0 -800 (-3558)

  7. OUTLINE • Unbonded post-tensioned precast walls • without supplemental damping • with supplemental damping • Unbonded post-tensioned hybrid coupled walls

  8. UNBONDED POST-TENSIONED WALLSWITHOUT SUPPLEMENTALENERGY DISSIPATIONAnalytical Modeling

  9. ANALYTICAL MODEL node truss element constraint fiber element wall model cross-section

  10. BEAM-COLUMN SUBASSEMBLAGE TESTS NIST (1993) N H upper crosshead 7.5 ft (2.3 m) 4.3 ft (1.3 m) lower crosshead

  11. MEASURED VERSUS PREDICTED RESPONSE lateral load, kips (kN) 50 measured (NIST) predicted drift, % -6 6 0 -50 (222) El-Sheikh et al. 1997

  12. FINITE ELEMENT (ABAQUS) MODEL nonlinear plane stress elements truss elements contact elements

  13. GAP OPENING

  14. FINITE ELEMENT VERSUS FIBER ELEMENT base shear, kips (kN) 1000 (4448) yielding state 500 gap opening state finite element fiber element 0 0.5 1 1.5 2 2.5 roof drift, %

  15. Seismic Design andResponse Evaluation

  16. DESIGN OBJECTIVES immediate occupancy collapse prevention base shear design level gr. mt. survival level gr. mt. roof drift

  17. BUILDING LAYOUT FOR HIGH SEISMICITY 8 x 24 ft = 192 ft (60 m) gravity load frame lateral load frame hollow- core panels wall N 110 ft (35 m) S inverted T-beam L-beam column

  18. WALL WH1CROSS SECTION C L PT bars ap=1.5 in2 (9.6 cm2) fpi=0.60fpu #3 spirals rsp=7% 12 in (31 cm) 10 ft (3 m) half wall length

  19. ROOF-DRIFT TIME-HISTORY roof drift, % 4 2 0 -2 Hollister (survival) unbonded PT precast wall cast-in-place RC wall -4 0 10 20 30 time, seconds

  20. WALLS WITH SUPPLEMENTAL ENERGY DISSIPATION U.S. National Science FoundationCMS 98-74872CAREER Program

  21. VISCOUS DAMPED WALLS viscous damper diagonal brace bracing column floor slab wall

  22. DAMPER DEFORMATION diagonal brace bracing column viscous damper wall panel gap

  23. DAMPER DEFORMATION 6 tension compression 5 4 at yielding state Dllp=0.84% floor 3 2 1 0 -2 (-5) -1 2 (5) 1 damper deformation, in (cm)

  24. DESIGN OBJECTIVE base shear SURVIVAL LEVEL GROUND MOTION damped system undamped system roof drift

  25. DAMPER DESIGN - WALL WH1 Sa, g 3 Dllp=0.84% MIV=67 in/sec (171 cm/sec) Te = 0.64 sec. xev=3% 2 Teff=0.80 sec. 10% xr=22% 15% 23% 1 30% 40% X 0 4 8 12 16 (41) spectral displacement Sd , in (cm)

  26. ROOF DRIFT TIME HISTORY - WALL WH1 D, % 3 damped Newhall, 0.66g undamped Dllp=0.84% 0 Dllp=0.84% -3 0 20 time, seconds

  27. MAXIMUM ROOF DRIFT - WALL WH1 Dmax, % 7 undamped wall damped wall Dllp= 0.84% 0 0.4 0.8 1.2 peak ground acceleration PGA, g

  28. MAXIMUM ROOF DRIFT - WALL WP1 Dmax, % 7 undamped wall damped wall Dllp= 1.14% 0 0.4 0.8 1.2 peak ground acceleration PGA, g

  29. MAXIMUM ROOF DRIFT - WALL WP2 Dmax, % 7 undamped wall damped wall Dllp= 1.47% 0 0.4 0.8 1.2 peak ground acceleration PGA, g

  30. 2 1.5 1 0.5 undamped wall damped wall 0 0.4 0.8 1.2 peak ground acceleration PGA, g MAXIMUM ROOF ACCELERATION - WALL WH1 amax, g

  31. U.S. National Science FoundationCMS 98-10067U.S.-Japan Cooperative Program onComposite and Hybrid Structures UNBONDED POST-TENSIONED HYBRID COUPLED WALL SYSTEMS

  32. EMBEDDED STEEL COUPLING BEAM embedment region steel beam

  33. TEST RESULTS FOR EMBEDDED BEAMS Harries et al.1997

  34. POST-TENSIONED COUPLING BEAM connection region PT anchor wall region beam PT steel angle embedded plate PT steel

  35. DEFORMED SHAPE contact region gap opening

  36. COUPLING FORCES Vcoupling P z db P lb Vcoupling P z Vcoupling = lb

  37. RESEARCH ISSUES • Force/deformation capacity of beam-wall connection region • beam • angle • Yielding of the PT steel • Energy dissipation • Self-centering • Overall/local stability

  38. ANALYTICAL WALL MODEL wall beam wall truss element kinematic constraint fiber element fiber element

  39. BEAM-WALL SUBASSEMBLAGE F L8x8x3/4 W18x234 PT strand lw = 10 ft lb = 10 ft (3.0 m) lw = 10 ft fpi = 0.5-0.7 fpu ap = 1.28 in2 (840 mm2)

  40. MOMENT-ROTATION BEHAVIOR moment Mb, kip.ft (kN.m) 2500 (3390) Mp My 1250 ultimate PT-yield softening decompression 0 2 4 6 8 10 rotation qb, percent

  41. CYCLIC LOAD BEHAVIOR moment Mb, kip.ft (kN.m) 2500 (3390) monotonic cyclic 0 -2500 -5 -10 0 5 10 rotation qb, percent

  42. ap and fpi (Pi = constant) moment Mb, kip.ft (kN.m) 2500 (3390) 1250 0 2 4 6 8 10 rotation qb, percent

  43. PT STEEL AREA moment Mb, kip.ft (kN.m) 2500 (3390) 1250 0 2 4 6 8 10 rotation qb, percent

  44. TRILINEAR ESTIMATION moment Mb, kip.ft (kN.m) 2500 (3390) 1250 ultimate PT-yield softening smooth relationship trilinear estimate 0 2 4 6 8 10 rotation qb, percent

  45. W18x234 82 ft (24.9 m) ap = 0.868 in2 (560 mm2) fpi = 0.7 fpu 12 ft 8 ft 12 ft (3.7m 2.4m 3.7 m) PROTOTYPE WALL

  46. COUPLING EFFECT base moment, kip.ft (kN.m) 120000 (162720) coupled wall 80000 40000 two uncoupled walls 0 1 2 3 4 roof drift, percent

  47. EXPERIMENTAL PROGRAM • Beam-wall connection subassemblages • Ten half-scale tests • Objectives • Investigate beam M-q behavior • Verify analytical model • Verify design tools and procedures

  48. ELEVATION VIEW (HALF-SCALE) L4x7x3/8 W10X100 PT strand strong floor lw = 5 ft lb = 5 ft (1.5 m) lw = 5 ft fpi = 0.7 fpu ap = 0.217 in2 (140 mm2)

  49. CONCLUSIONS • Unbonded post-tensioning is a feasible construction method for reinforced concrete walls in seismic regions • Large self-centering capability • Softening, thus, period elongation • Small inelastic energy dissipation • Need supplemental energy dissipation in high seismic regions

  50. http://www.nd.edu/~concrete

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