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UNBONDED POST-TENSIONED HYBRID COUPLED WALLS. Yahya C. KURAMA University of Notre Dame Notre Dame, Indiana Qiang SHEN, Michael MAY (graduate students). New Developments in Hybrid and Composite Construction ACI Fall 2001 Convention October 30, 2001 Dallas, Texas.
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UNBONDED POST-TENSIONEDHYBRID COUPLED WALLS Yahya C. KURAMA University of Notre Dame Notre Dame, Indiana Qiang SHEN, Michael MAY (graduate students) New Developments in Hybrid and Composite Construction ACI Fall 2001 Convention October 30, 2001 Dallas, Texas
UP COUPLED WALL SUBASSEMBLAGE steel concrete spiral connection region PT anchor wall region beam PT tendon cover plate angle embedded plate PT tendon
P z Vcoupling = lb DEFORMED SHAPE AND COUPLING FORCES contact region gap opening Vcoupling P z db P lb Vcoupling
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
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
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
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
beam rotation=3.3% FINITE ELEMENT MODEL (ABAQUS)
(ksi) BEAM STRESSES
(ksi) beam side PT anchor side CONCRETE STRESSES
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 (%)
BEAM-WALL SUBASSEMBLAGE F L8x8x1-1/8 W21x182 lw = 3.0 m lb = 3.0 m (10 ft) lw = 3.0 m fpi = 0.6 fpu ap = 420 mm2 (0.65 in2)
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 (%)
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 (%)
PROTOTYPE WALL 32.6 m (107 ft) 8.5 m 8.5 m 8.5 m (28 ft 28 ft 28 ft) 6 m 6 m 6 m 6 m 6 m (20 ft 20 ft 20 ft 20 ft 20 ft) 3.0m 3.0m 3.0 m PLAN VIEW W21x182 (10 ft 10 ft 10 ft) ap = 398 mm2 (0.612 in2) fpi = 0.625 fpu
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 (%)
COUPLED WALL BEHAVIOR overturning/base moment (kN.m) overturning/base moment (kN.m) 90000 90000 CIP wall w/ UP beams precast wall w/ UP beams 1st beam gap opening left wall concrete cracking left wall gap opening 1st beam gap opening right wall gap opening softening of left wall softening of left wall 1st beam angle yielding right wall concrete cracking 1st beam cover plate yielding softening of right wall softening of right wall 1st wall mild steel yielding 1st wall PT-bar yielding 1st beam angle yielding 1st beam flange yielding 1st beam cover plate yielding 1st beam PT-tendon yielding 1st beam PT-tendon yielding right wall concrete crushing two uncoupled walls two uncoupled walls right wall in coupled system right wall in coupled system left wall in coupled system left wall in coupled system 3 0 3 0 roof drift (%) roof drift (%)
CAST-IN-PLACE WALL PARAMETRIC STUDY overturning moment (kN.m) overturning moment (kN.m) 100000 100000 lw=3.05m softening of left wall softening of left wall ws=1.38% softening of right wall softening of right wall lw=2.29m ws=1.73% 1st wall mild steel yield 1st wall mild steel yield lw=3.81m 1st beam angle yield 1st beam angle yield ws=2.07% 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield 0 roof drift (%) roof drift (%) 3 0 3 overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall softening of left wall fbpi=0.625fbpu abp=395mm2 softening of right wall softening of right wall fbpi=0.525fbpu abp=198mm2 1st wall mild steel yield 1st wall mild steel yield 1st beam angle yield 1st beam angle yield abp=593mm2 fbpi=0.725fbpu 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield 0 3 0 3 roof drift (%) roof drift (%)
PRECAST WALL PARAMETRIC STUDY overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall softening of left wall lw=3.05 m wp=1.13% 1st beam angle yield 1st beam angle yield softening of right wall softening of right wall lw=2.29 m wp=1.41% 1st wall PT-bar yield 1st wall PT-bar yield lw=3.81 m wp=1.69% 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield right concrete crush right concrete crush 0 roof drift (%) 3 0 roof drift (%) 3 overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall softening of left wall fbpi=0.625fbpu 1st beam angle yield 1st beam angle yield abp=395mm2 softening of right wall softening of right wall fbpi=0.525fbpu abp=198mm2 1st wall PT-bar yield 1st wall PT-bar yield abp=593mm2 fbpi=0.725fbpu 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield right concrete crush right concrete crush 0 roof drift (%) 3 0 roof drift (%) 3
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 (%)
CYCLIC BEHAVIOR precast wall w/ UP beams CIP wall w/ UP beams 80000 80000 0 0 overturning moment (kN.m) overturning moment (kN.m) -80000 -80000 2.5 0 2.5 2.5 0 2.5 roof drift (%) roof drift (%) CIP wall w/ embedded beams CIP wall w/ UP beams w/o angles 80000 80000 0 0 overturning moment (kN.m) overturning moment (kN.m) -80000 -80000 2.5 0 2.5 2.5 0 2.5 roof drift (%) roof drift (%)
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 (%)
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)
DUCTILITY DEMAND SPECTRA BP, mean regression br = bs = 1/3, a=0.10, High Seismicity, Stiff (Sd) Soil, R=1, 2, 4, 6, 8 (thin thick) 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)
MDOF DYNAMIC ANALYSES (SAC-LA37-2%50yrs) precast wall w/ UP beams CIP wall w/ UP beams 3 3 uncoupled walls uncoupled walls coupled walls coupled walls 0 0 roof-drift (%) roof-drift (%) -3 -3 0 time (seconds) 20 0 time (seconds) 20 CIP wall w/ embedded beams CIP wall w/ UP beams w/o angles 3 3 0 0 roof-drift (%) roof-drift (%) -3 -3 0 20 0 time (seconds) 20 time (seconds)
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 = 1.5 m lb = 1.5 m (5 ft) lw = 1.5 m fpi = 0.6 fpu ap = 140 mm2 (0.217 in2)
EXPERIMENTAL SET-UP actuators wall beam load block
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
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