UNBONDED POST-TENSIONEDHYBRID COUPLED WALLSYahya C. KURAMAUniversity of Notre DameNotre Dame, Indiana

Qiang SHEN, Michael MAY (graduate students)Cooperative Earthquake Research Program on Composite and Hybrid StructuresJune 24-25, 2001Berkeley, California

UP COUPLED WALL SUBASSEMBLAGEbeamPT tendonconnectionregionPTanchorembeddedplateanglePT tendonwall regionspiralcover plateconcretesteel

DEFORMED SHAPE AND COUPLING FORCEScontactregiongapopeningPPVcouplingVcouplingdbzlb

BROAD OBJECTIVESInvestigate feasibility and limitationsDevelop seismic design approachEvaluate seismic responseRESEARCH ISSUESForce/deformation capacity of beam-wall connection regionYielding of the PT steelEnergy dissipationSelf-centeringOverall/local stabilityRESEARCH PHASESSubassemblage behavior: analytical and experimentalMulti-story coupled wall behavior: analytical

ANALYTICAL WALL MODEL (DRAIN-2DX)fiberelementkinematicconstrainttrusselement wall beam wall

MATERIAL PROPERTIESstressstrainTENSIONcompression-only steel fiberTENSIONstressstraincompression-only concrete fiber

ANGLE MODELbolt orPT anchorT ay seat angle at tension yieldingfiber 1angle modelfiber 2axialforceTENSIONdef.axialforceTENSIONdeformationaxialforceTENSIONdeformation= +Kishi and Chen (1990)Tay

FINITE ELEMENT MODEL (ABAQUS)

BEAM STRESSES

CONCRETE STRESSES

DRAIN-2DX VERSUS ABAQUS80050ABAQUS (rigid)ABAQUS (deformable)beam shear (kN)beam rotation (%)05d = 718 mm1000DRAIN-2DX (deformable)ABAQUS (deformable)b d = 577 mmbbeam shear (kN)beam rotation (%)contact/beam depth 501.0DRAIN-2DX (deformable)ABAQUS (deformable)beam rotation (%)5DRAIN-2DX (rigid)ABAQUS (rigid)01000beam rotation (%)beam shear (kN)

BEAM-WALL SUBASSEMBLAGEW21x182L8x8x1-1/8ap = 0.65 in2 (420 mm2) lw = 10 ft lb = 10 ft (3.0 m) lw = 10 ft Ffpi = 0.6 fpu

LATERAL LOAD BEHAVIOR06-602500-2500L8x8x3/406-602500-2500L8x8x1-1/8beam rotation (%)beam moment (kN.m)beam rotation (%)beam moment (kN.m)02500-250006-6no anglebeam rotation (%)beam moment (kN.m)beam moment (kN.m)MpMycover plate yieldingtension angle yieldingdecompression603000 PT-yieldingbeam rotation (%)flange yld.

PARAMETRIC INVESTIGATIONBeam cross-section Wall lengthBeam lengthPT steel areaInitial PT stressAngle sizeCover plate size DESIGN PARAMETERS RESPONSE PARAMETERSDecompressionTension angle yieldingCover plate yieldingBeam flange yieldingPT tendon yielding 30000 6beam moment (kN.m) beam rotation (%)analytical modelbilinear estimationdecompressioncover plate yieldingtension angle yieldingPT tendon yieldingbeam flange yieldingestimation points80 3000beam moment (kN.m) beam rotation (%)decompressioncover plate yieldingtension angle yieldingPT tendon yieldingbeam flange yieldingap=560mm2ap=420mm2ap=280mm2

PROTOTYPE WALLW21x182ap = 0.868 in2 (560 mm2)fpi = 0.65 fpu 10 ft 10 ft 10 ft107 ft(32.6 m) (3.0m 3.0m 3.0 m)PLAN VIEW20 ft 20 ft 20 ft 20 ft 20 ft28 ft 28 ft 28 ft

COUPLED WALL BEHAVIORbase moment (kip.ft)02.5 120000roof drift (%)coupled wallright wallleft wall04roof drift (%) 120000base moment (kip.ft)coupled walltwo uncoupled walls

CYCLIC BEHAVIOR-1.501.5-100001000-1.501.5-100001000-1.501.5-100001000base shear (kips)roof drift (%)-100001000-303base shear (kips)roof drift (%)base shear (kips)roof drift (%)base shear (kips)roof drift (%)8-story precast wall w/ UP beams6-story precast wall w/ UP beams6-story CIP wall w/ UP beams6-story CIP wall w/ embedded beams

base shear, V (kips)DESIGN APPROACH304500roof drift, D (%)1st beam angle yielding 1st beam flange yielding wall base concrete crushing Design EQSurvival EQKK(R/m)VdesVdes/RDdesDsur

MAXIMUM DISPLACEMENT DEMAND(Nassar & Krawinkler, 1991) 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 ProfilesBilinear-Elastic (BE)Elasto-Plastic (EP)Bilinear-Elastic/ Elasto-Plastic (BP)+=FFFDDD(Fbe,Dbe)kbe(brFbe,Dbe)bskbe[(1+br)Fbe,Dbe](1+bs)kbeakbeakbeR=[c(m-1)+1]1/cc= + Ta bTa+1 T

1403.5period, T (sec)1403.5Design EQ (SAC): a=3.83, b=0.87Survival EQ (SAC): a=1.08, b=0.89ductility demand, mperiod, T (sec)ductility demand, mDUCTILITY DEMAND SPECTRA0143.5 period, T (sec)0143.5 period, T (sec)ductility demand, mductility demand, mEP, meanBP, meanBE, meanSurvival EQ (SAC): BP versus EPSurvival EQ (SAC): BP versus BE

EXPERIMENTAL PROGRAMObjectivesInvestigate beam M-q behaviorVerify analy. modelVerify design tools and proceduresBeam-wall connection subassemblagesTen half-scale tests (angle, beam, post-tensioning properties)W10x68PT strandL4x8x3/4ap = 0.217 in2 (140 mm2) lw = 5 ft lb = 5 ft (1.5 m) lw = 5 ft strong floorfpi = 0.65 fpuElevation View (half-scale)load block

EXPERIMENTAL SET-UPbeamwallload blockactuators

SUMMARY AND CONCLUSIONS

Beam BehaviorAnalytical models seem to work wellGap opening governs behaviorLarge self-centering, limited energy dissipationLarge deformations with little damageBilinear estimation for beam behaviorExperimental verification

Wall BehaviorLevel of coupling up to 60-65 percentTwo-level performance based design approach~25% larger displacements compared to embedded systems

ONGOING WORKSubassemblage testsDesign/analysis of multi-story wallsDynamic analyses of multi-story wallsACKNOWLEDGMENTSNational Science Foundation (Dr. S. C. Liu)University of Notre DameCSR American Precast, Inc.Dywidag Systems International, U.S.A, Inc.Insteel Wire ProductsAmbassador SteelIvy Steel & WireDayton/Richmond Concrete Accessories