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

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

DEFORMED SHAPE AND COUPLING FORCES contact region gap opening V coupling = P z lblb P P V coupling dbdb z lblb

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

ANALYTICAL WALL MODEL (DRAIN-2DX) fiber element kinematic constraint truss element wall beam wall

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

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

beam rotation=3.3% FINITE ELEMENT MODEL (ABAQUS)

BEAM STRESSES (ksi)

beam side PT anchor side CONCRETE STRESSES (ksi)

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

BEAM-WALL SUBASSEMBLAGE W21x182 L8x8x1-1/8 a p = 0.65 in 2 (420 mm 2 ) l w = 10 ft l b = 10 ft (3.0 m) l w = 10 ft F f pi = 0.6 f pu

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

PARAMETRIC INVESTIGATION Beam cross-section Wall length Beam length PT steel area Initial PT stress Angle size Cover plate size DESIGN PARAMETERS RESPONSE PARAMETERS Decompression Tension angle yielding Cover plate yielding Beam flange yielding PT tendon yielding beam moment (kN.m) beam rotation (%) analytical model bilinear estimation decompression cover plate yielding tension angle yielding PT tendon yielding beam flange yielding estimation points beam moment (kN.m) beam rotation (%) decompression cover plate yielding tension angle yielding PT tendon yielding beam flange yielding a p =560mm 2 a p =420mm 2 a p =280mm 2

PROTOTYPE WALL W21x182 a p = in 2 (560 mm 2 ) f pi = 0.65 f pu 10 ft 10 ft 10 ft 107 ft (32.6 m) (3.0m 3.0m 3.0 m) PLAN VIEW 20 ft 20 ft 20 ft 20 ft 20 ft 28 ft 28 ft 28 ft

COUPLED WALL BEHAVIOR base moment (kip.ft) roof drift (%) coupled wall right wall left wall 04 roof drift (%) base moment (kip.ft) coupled wall two uncoupled walls

CYCLIC BEHAVIOR base shear (kips) roof drift (%) base shear (kips) roof drift (%) base shear (kips) roof drift (%) base shear (kips) roof drift (%) 8-story precast wall w/ UP beams 6-story precast wall w/ UP beams 6-story CIP wall w/ UP beams 6-story CIP wall w/ embedded beams

base shear, V (kips) DESIGN APPROACH roof drift,  (%) 1st beam angle yielding 1st beam flange yielding wall base concrete crushing 1st beam PT tendon yielding Design EQ Survival EQ K K(R  V des V des /R  des  sur

MAXIMUM DISPLACEMENT DEMAND (Nassar & Krawinkler, 1991)  r =  s = 1/4, 1/3, 1/2  = 0.02, 0.10 Moderate and High Seismicity Design-Level and Survival-Level Stiff Soil and Medium Soil Profiles Bilinear-Elastic (BE)Elasto-Plastic (EP)Bilinear-Elastic/ Elasto-Plastic (BP) += F FF  (F be,  be ) k be (  r F be,  be )  s k be [(1+  r )F be,  be ] (1+  s )k be  k be R=[c  1)+1] 1/c c= + T a b T a +1 T

period, T (sec) Design EQ (SAC): a=3.83, b=0.87Survival EQ (SAC): a=1.08, b=0.89 ductility demand,  period, T (sec) ductility demand,  DUCTILITY DEMAND SPECTRA period, T (sec) period, T (sec) regression BP, mean ductility demand,  EP, mean BP, mean BE, mean Survival EQ (SAC): BP versus EPSurvival EQ (SAC): BP versus BE  r =  s = 1/3,  =0.10, High Seismicity, Stiff Soil, R=1, 2, 4, 6, 8 (thin thick)

EXPERIMENTAL PROGRAM Objectives Investigate beam M-  behavior Verify analy. model Verify design tools and procedures Beam-wall connection subassemblages Ten half-scale tests (angle, beam, post-tensioning properties) W10x68 PT strand L4x8x3/4 a p = in 2 (140 mm 2 ) l w = 5 ft l b = 5 ft (1.5 m) l w = 5 ft strong floor f pi = 0.65 f pu Elevation View (half-scale) load block

EXPERIMENTAL SET-UP beam wall load block actuators

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 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