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

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

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

BROAD OBJECTIVES RESEARCH ISSUES RESEARCH PHASES 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

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

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

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

FINITE ELEMENT MODEL (ABAQUS) beam rotation=3.3%

BEAM STRESSES (ksi)

CONCRETE STRESSES (ksi) beam side PT anchor

DRAIN-2DX VERSUS ABAQUS beam shear (kN) beam shear (kN) 800 1000 ABAQUS (rigid) ABAQUS (deformable) ABAQUS (rigid) DRAIN-2DX (rigid) beam rotation (%) 5 5 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) 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) 3000 2500 p PT-yielding M y flange yld. cover plate yielding tension angle yielding L8x8x1-1/8 decompression -2500 6 -6 6 beam rotation (%) beam rotation (%) beam moment (kN.m) beam moment (kN.m) 2500 2500 L8x8x3/4 no angle -2500 -2500 -6 -6 6 6 beam rotation (%) beam rotation (%)

PARAMETRIC INVESTIGATION DESIGN PARAMETERS RESPONSE PARAMETERS Beam cross-section Wall length Beam length PT steel area Initial PT stress Angle size Cover plate size Decompression Tension angle yielding Cover plate yielding Beam flange yielding PT tendon yielding 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 tension angle yielding cover plate yielding cover plate yielding beam flange yielding beam flange yielding PT tendon yielding PT tendon yielding estimation points 8 6 beam rotation (%) beam rotation (%)

PROTOTYPE WALL 8.5 m 8.5 m 8.5 m (28 ft 28 ft 28 ft) 32.6 m (107 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 (10 ft 10 ft 10 ft) W21x182 ap = 398 mm2 (0.612 in2) fpi = 0.625 fpu

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

COUPLED WALL BEHAVIOR 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 right wall concrete cracking 1st beam angle yielding 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 3 roof drift (%) roof drift (%)

CAST-IN-PLACE WALL PARAMETRIC STUDY overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall lw=3.05m softening of left wall ws=1.38% softening of right wall lw=2.29m softening of right wall 1st wall mild steel yield 1st wall mild steel yield ws=1.73% 1st beam angle yield lw=3.81m 1st beam angle yield ws=2.07% 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield roof drift (%) 3 roof drift (%) 3 overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall abp=395mm2 softening of left wall fbpi=0.625fbpu softening of right wall softening of right wall 1st wall mild steel yield abp=198mm2 1st wall mild steel yield fbpi=0.525fbpu 1st beam angle yield abp=593mm2 1st beam angle yield fbpi=0.725fbpu 1st beam flange yield 1st beam flange yield 1st beam tendon yield 1st beam tendon yield roof drift (%) 3 roof drift (%) 3

PRECAST WALL PARAMETRIC STUDY overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall softening of left wall 1st beam angle yield lw=3.05 m 1st beam angle yield wp=1.13% softening of right wall lw=2.29 m softening of right wall wp=1.41% 1st wall PT-bar yield 1st wall PT-bar yield lw=3.81 m 1st beam flange yield 1st beam flange yield wp=1.69% 1st beam tendon yield 1st beam tendon yield right concrete crush right concrete crush roof drift (%) 3 roof drift (%) 3 overturning moment (kN.m) overturning moment (kN.m) 100000 100000 softening of left wall softening of left wall 1st beam angle yield abp=395mm2 1st beam angle yield fbpi=0.625fbpu softening of right wall softening of right wall abp=198mm2 fbpi=0.525fbpu 1st wall PT-bar yield 1st wall PT-bar yield 1st beam flange yield abp=593mm2 1st beam flange yield fbpi=0.725fbpu 1st beam tendon yield 1st beam tendon yield right concrete crush right concrete crush roof drift (%) 3 roof drift (%) 3

CYCLIC BEHAVIOR 8-story precast wall w/ UP beams 1000 1000 base shear (kips) base shear (kips) -1000 -1000 -3 3 -1.5 1.5 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) -1000 -1000 -1.5 1.5 -1.5 1.5 roof drift (%) roof drift (%)

CYCLIC BEHAVIOR CIP wall w/ UP beams precast wall w/ UP beams 80000 80000 overturning moment (kN.m) overturning moment (kN.m) -80000 -80000 2.5 2.5 2.5 2.5 roof drift (%) roof drift (%) CIP wall w/ embedded beams CIP wall w/ UP beams w/o angles 80000 80000 overturning moment (kN.m) overturning moment (kN.m) -80000 -80000 2.5 2.5 2.5 2.5 roof drift (%) roof drift (%)

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

MAXIMUM DISPLACEMENT DEMAND F F F akbe akbe [(1+br)Fbe,Dbe] (Fbe,Dbe) (brFbe,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 Ta b c= + Ta+1 T (Nassar & Krawinkler, 1991)

DUCTILITY DEMAND SPECTRA 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 regression BP, mean 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 3.5 3.5 period, T (sec) period, T (sec)

MDOF DYNAMIC ANALYSES (SAC-LA37-2%50yrs) CIP wall w/ UP beams precast wall w/ UP beams 3 3 uncoupled walls uncoupled walls coupled walls coupled walls roof-drift (%) roof-drift (%) -3 -3 time (seconds) 20 time (seconds) 20 CIP wall w/ embedded beams CIP wall w/ UP beams w/o angles 3 3 roof-drift (%) roof-drift (%) -3 -3 time (seconds) 20 time (seconds) 20

Elevation View (half-scale) 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 ACKNOWLEDGMENTS 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