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.
Download ReportTranscript 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.
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 concrete steel PT anchor spiral beam connection region wall region PT tendon cover plate angle embedded plate PT tendon DEFORMED SHAPE AND COUPLING FORCES contact region gap opening Vcoupling P z lb Pz Vcoupling = lb Vcoupling d P b 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) wall beam wall RIGHT WALL REGION LEFT WALL REGION truss element fiber element angle element beam elements wallheight elements truss kinematic element constraint kinematic constraint slope= 1:3 embedded plate kinematic constraint modeling of wall contact regions wallcontact elements MATERIAL PROPERTIES stress stress TENSION TENSION strain compression-only steel fiber stress TENSION strain compression-tension steel fiber strain compression-only concrete fiber stress TENSION strain truss element ANGLE MODEL Tay Kishi and Chen (1990) seat angle at tension yielding bolt or PT anchor axial force axial force TENSION Tay = deformation angle model axial force TENSION TENSION + deformation fiber 1 def. fiber 2 FINITE ELEMENT MODEL (ABAQUS) beam rotation=3.3% BEAM STRESSES (ksi) CONCRETE STRESSES (ksi) PT anchor side beam side DRAIN-2DX VERSUS ABAQUS beam shear (kN) 1000 beam shear (kN) 800 ABAQUS (rigid) DRAIN-2DX (rigid) ABAQUS (deformable) ABAQUS (rigid) 0 beam rotation (%) 5 beam shear (kN) 0 beam rotation (%) 5 contact/beam depth 1.0 1000 db= 718 mm ABAQUS (deformable) DRAIN-2DX (deformable) d b= 577 mm ABAQUS (deformable) DRAIN-2DX (deformable) 0 beam rotation (%) 5 0 beam rotation (%) 5 BEAM-WALL SUBASSEMBLAGE F L8x8x1-1/8 W21x182 lw = 10 ft lb = 10 ft (3.0 m) fpi = 0.6 fpu lw = 10 ft ap = 0.65 in2 (420 mm2) LATERAL LOAD BEHAVIOR beam moment (kN.m) 3000 Mp My beam moment (kN.m) 2500 PT-yielding flange yld. cover plate yielding tension angle yielding 0 L8x8x1-1/8 decompression 0 beam rotation (%) 6 beam moment (kN.m) -2500 -6 6 beam moment (kN.m) 2500 2500 0 0 L8x8x3/4 no angle -2500 -2500 -6 0 beam rotation (%) 0 beam rotation (%) 6 -6 0 beam rotation (%) 6 PARAMETRIC INVESTIGATION DESIGN PARAMETERS • • • • • • • RESPONSE PARAMETERS • • • • • Beam cross-section Wall length Beam length PT steel area Initial PT stress Angle size Cover plate size beam moment (kN.m) 3000 ap=560mm2 Decompression Tension angle yielding Cover plate yielding Beam flange yielding PT tendon yielding beam moment (kN.m) 3000 bilinear estimation analytical model ap=420mm2 ap=280mm2 decompression tension angle yielding cover plate yielding beam flange yielding PT tendon yielding estimation points decompression tension angle yielding cover plate yielding beam flange yielding PT tendon yielding 0 beam rotation (%) 8 0 beam rotation (%) 6 28 ft 28 ft PROTOTYPE WALL 28 ft 107 ft (32.6 m) 20 ft 20 ft 10 ft 10 ft 10 ft (3.0m 3.0m 3.0 m) 20 ft 20 ft PLAN VIEW W21x182 ap = 0.868 in2 (560 mm2) fpi = 0.65 fpu 20 ft COUPLED WALL BEHAVIOR base moment (kip.ft) 120000 base moment (kip.ft) 120000 coupled wall coupled wall two uncoupled walls right wall left wall 0 roof drift (%) 2.5 0 roof drift (%) 4 CYCLIC BEHAVIOR 6-story precast wall w/ UP beams 8-story precast wall w/ UP beams 1000 base shear (kips) base shear (kips) 1000 0 -1000 -3 0 roof drift (%) 3 0 roof drift (%) 1.5 1000 6-story CIP wall w/ embedded beams 1000 base shear (kips) -1000 -1.5 base shear (kips) 6-story CIP wall w/ UP beams 0 0 -1000 -1.5 0 roof drift (%) 1.5 0 -1000 -1.5 0 roof drift (%) 1.5 base shear, V (kips) 4500 DESIGN APPROACH 1st beam angle yielding 1st beam flange yielding Survival EQ 1st beam PT tendon yielding wall base concrete crushing Vdes Design EQ K K(R/m) Vdes/R 0 Ddes roof drift, D (%) Dsur 3 MAXIMUM DISPLACEMENT DEMAND F (Fbe,Dbe) F akbe [(1+br)Fbe,Dbe] (brFbe,Dbe) D D + kbe Bilinear-Elastic (BE) F akbe D = (1+bs)kbe bskbe Elasto-Plastic (EP) • 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 Bilinear-Elastic/ Elasto-Plastic (BP) R=[c(m-1)+1]1/c c= Ta Ta+1 + b T (Nassar & Krawinkler, 1991) DUCTILITY DEMAND SPECTRA br = bs = 1/3, a=0.10, High Seismicity, Stiff 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 BP, mean regression 0 period, T (sec) 0 3.5 Survival EQ (SAC): BP versus EP ductility demand, m 14 period, T (sec) 3.5 Survival EQ (SAC): BP versus BE ductility demand, m 14 BP, mean EP, mean BE, mean 0 period, T (sec) 3.5 0 period, T (sec) 3.5 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 PT strand load block W10x68 strong floor lw = 5 ft lb = 5 ft (1.5 m) fpi = 0.65 fpu lw = 5 ft ap = 0.217 in2 (140 mm2) 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