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UNBONDED POST-TENSIONED HYBRID COUPLED WALLS

UNBONDED POST-TENSIONED HYBRID COUPLED WALLS. Yahya C. KURAMA University of Notre Dame Notre Dame, Indiana Qiang SHEN, Michael MAY (graduate students). Cooperative Earthquake Research Program on Composite and Hybrid Structures June 24-25, 2001 Berkeley, California.

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UNBONDED POST-TENSIONED HYBRID COUPLED WALLS

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  1. UNBONDED POST-TENSIONEDHYBRID COUPLED WALLS Yahya C. KURAMA University of Notre Dame Notre Dame, Indiana Qiang SHEN, Michael MAY (graduate students) Cooperative Earthquake Research Program on Composite and Hybrid Structures June 24-25, 2001 Berkeley, California

  2. UP COUPLED WALL SUBASSEMBLAGE steel concrete spiral connection region PT anchor wall region beam PT tendon cover plate angle embedded plate PT tendon

  3. P z Vcoupling = lb DEFORMED SHAPE AND COUPLING FORCES contact region gap opening Vcoupling P z db P lb Vcoupling

  4. BROAD OBJECTIVES • Investigate feasibility and limitations • Develop seismic design approach • Evaluate seismic response RESEARCH ISSUES • Force/deformation capacity of beam-wall connection region • Yielding of the PT steel • Energy dissipation • Self-centering • Overall/local stability RESEARCH PHASES • Subassemblage behavior: analytical and experimental • Multi-story coupled wall behavior: analytical

  5. RIGHT WALL REGION LEFT WALL REGION wall- angle element wall- height beam elements contact elements elements truss kinematic kinematic element constraint constraint slope= 1:3 embedded plate modeling of wall contact regions ANALYTICAL WALL MODEL (DRAIN-2DX) wall beam wall truss element fiber element kinematic constraint

  6. stress stress TENSION TENSION strain strain compression-tension steel fiber truss element MATERIAL PROPERTIES stress stress TENSION TENSION strain strain compression-only steel fiber compression-only concrete fiber

  7. ANGLE MODEL T Kishi and Chen (1990) ay seat angle at bolt or PT anchor tension yielding axial force axial force axial force TENSION TENSION TENSION Tay = + deformation deformation def. angle model fiber 1 fiber 2

  8. beam rotation=3.3% FINITE ELEMENT MODEL (ABAQUS)

  9. (ksi) BEAM STRESSES

  10. (ksi) beam side PT anchor side CONCRETE STRESSES

  11. DRAIN-2DX VERSUS ABAQUS beam shear (kN) beam shear (kN) 800 1000 ABAQUS (rigid) ABAQUS (deformable) DRAIN-2DX (rigid) ABAQUS (rigid) 0 0 5 5 beam rotation (%) beam rotation (%) beam shear (kN) contact/beam depth 1000 1.0 d = 718 mm b ABAQUS (deformable) d = 577 mm DRAIN-2DX (deformable) b ABAQUS (deformable) DRAIN-2DX (deformable) 0 0 5 5 beam rotation (%) beam rotation (%)

  12. BEAM-WALL SUBASSEMBLAGE F L8x8x1-1/8 W21x182 lw = 10 ft lb = 10 ft (3.0 m) lw = 10 ft fpi = 0.6 fpu ap = 0.65 in2 (420 mm2)

  13. LATERAL LOAD BEHAVIOR beam moment (kN.m) beam moment (kN.m) 2500 3000 M p PT-yielding M y flange yld. 0 cover plate yielding tension angle yielding L8x8x1-1/8 decompression -2500 0 -6 0 6 6 beam rotation (%) beam rotation (%) beam moment (kN.m) beam moment (kN.m) 2500 2500 0 0 L8x8x3/4 no angle -2500 -2500 -6 0 6 -6 0 6 beam rotation (%) beam rotation (%)

  14. PARAMETRIC INVESTIGATION DESIGN PARAMETERSRESPONSE PARAMETERS • Decompression • Tension angle yielding • Cover plate yielding • Beam flange yielding • PT tendon yielding • Beam cross-section • Wall length • Beam length • PT steel area • Initial PT stress • Angle size • Cover plate size beam moment (kN.m) beam moment (kN.m) 3000 3000 ap=560mm2 bilinear estimation ap=420mm2 analytical model ap=280mm2 decompression decompression tension angle yielding cover plate yielding tension angle yielding cover plate yielding beam flange yielding beam flange yielding PT tendon yielding estimation points PT tendon yielding 0 6 0 8 beam rotation (%) beam rotation (%)

  15. PROTOTYPE WALL 107 ft (32.6 m) 28 ft 28 ft 28 ft 20 ft 20 ft 20 ft 20 ft 20 ft PLAN VIEW 10 ft 10 ft 10 ft W21x182 (3.0m 3.0m 3.0 m) ap = 0.868 in2 (560 mm2) fpi = 0.65 fpu

  16. COUPLED WALL BEHAVIOR base moment (kip.ft) base moment (kip.ft) 120000 120000 coupled wall coupled wall two uncoupled walls right wall left wall 0 2.5 0 4 roof drift (%) roof drift (%)

  17. CYCLIC BEHAVIOR 6-story precast wall w/ UP beams 8-story precast wall w/ UP beams 1000 1000 base shear (kips) 0 0 base shear (kips) -1000 -1000 0 1.5 -1.5 -3 0 3 roof drift (%) roof drift (%) 6-story CIP wall w/ UP beams 6-story CIP wall w/ embedded beams 1000 1000 base shear (kips) base shear (kips) 0 0 -1000 -1000 0 -1.5 1.5 0 1.5 -1.5 roof drift (%) roof drift (%)

  18. DESIGN APPROACH 1st beam PT tendon yielding base shear, V (kips) 4500 1st beam angle yielding Survival EQ 1st beam flange yielding wall base concrete crushing Design EQ Vdes K K(R/m) Vdes/R 0 Dsur Ddes 3 roof drift, D (%)

  19. MAXIMUM DISPLACEMENT DEMAND F F F akbe akbe [(1+br)Fbe,Dbe] (brFbe,Dbe) (Fbe,Dbe) D D D + = kbe (1+bs)kbe bskbe Bilinear-Elastic (BE) Elasto-Plastic (EP) Bilinear-Elastic/ Elasto-Plastic (BP) • br = bs = 1/4, 1/3, 1/2 • a = 0.02, 0.10 • Moderate and High Seismicity • Design-Level and Survival-Level • Stiff Soil and Medium Soil Profiles R=[c(m-1)+1]1/c Tab c= + Ta+1 T (Nassar & Krawinkler, 1991)

  20. DUCTILITY DEMAND SPECTRA br = bs = 1/3, a=0.10, High Seismicity, Stiff Soil, R=1, 2, 4, 6, 8 (thin thick) BP, mean regression Design EQ (SAC): a=3.83, b=0.87 Survival EQ (SAC): a=1.08, b=0.89 ductility demand, m ductility demand, m 14 14 0 0 3.5 3.5 period, T (sec) period, T (sec) Survival EQ (SAC): BP versus EP Survival EQ (SAC): BP versus BE ductility demand, m ductility demand, m 14 14 BP, mean EP, mean BE, mean 0 0 3.5 3.5 period, T (sec) period, T (sec)

  21. EXPERIMENTAL PROGRAM • Beam-wall connection subassemblages • Ten half-scale tests (angle, beam, post-tensioning properties) Elevation View (half-scale) • Objectives • Investigate beam M-q behavior • Verify analy. model • Verify design tools and procedures L4x8x3/4 load block W10x68 PT strand strong floor lw = 5 ft lb = 5 ft (1.5 m) lw = 5 ft fpi = 0.65 fpu ap = 0.217 in2 (140 mm2)

  22. EXPERIMENTAL SET-UP actuators wall beam load block

  23. SUMMARY AND CONCLUSIONS Beam Behavior • Analytical models seem to work well • Gap opening governs behavior • Large self-centering, limited energy dissipation • Large deformations with little damage • Bilinear estimation for beam behavior • Experimental verification • Wall Behavior • Level of coupling up to 60-65 percent • Two-level performance based design approach • ~25% larger displacements compared to embedded systems

  24. ONGOING WORK • Subassemblage tests • Design/analysis of multi-story walls • Dynamic analyses of multi-story walls ACKNOWLEDGMENTS • National Science Foundation (Dr. S. C. Liu) • University of Notre Dame • CSR American Precast, Inc. • Dywidag Systems International, U.S.A, Inc. • Insteel Wire Products • Ambassador Steel • Ivy Steel & Wire • Dayton/Richmond Concrete Accessories

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