Partially Post-Tensioned Precast Concrete Walls Yahya C. (Gino) Kurama Assistant Professor University of Notre Dame Notre Dame, Indiana, USA American Concrete Institute Spring 2003 Convention Vancouver, Canada April 2, 2003

POST-TENSIONED PRECAST CONCRETE WALL anchorage wall panel horizontal joint unbonded PT bars spiral reinforcement foundation spiral unbonded bonded reinforcement wire mesh PT bar precast wall with full PT

BEHAVIOR UNDER LATERAL LOADS gap opening

HYSTERETIC BEHAVIOR base shear, kips (kN) 800 (3558) roof drift, % -2 -1 1 2 -800 (-3558)

VERTICALLY JOINTED WALLS friction or metallic-yield damper Priestley et al. Perez et al. Kurama Pall et al.

DISPLACED SHAPE

WALLS WITH PARTIAL POST-TENSIONING unbonded PT bar bonded mild bar unbonded bonded PT bar mild bar precast wall with partial PT

ENERGY DISSIPATION mild steel yielding

PARTIALLY POST-TENSIONED PRECAST FRAME column fiber reinforced grout mild steel bar trough beam PT tendon beam-to-column joint Cheok et al. Priestley et al. Stanton et al. Nakaki et al.

OBJECTIVES Investigate precast wall systems with PT steel and mild steel Develop seismic design approach Evaluate seismic response

OUTLINE Prototype walls and expected behavior Seismic design approach and evaluation Summary and conclusions

PROTOTYPE WALLS Four fully post-tensioned walls Four walls with only mild steel (emulative walls) Four partially post-tensioned walls

PLAN LAYOUT OF PROTOTYPE BUILDINGS 8 x 24 ft = 192 ft (58.5 m) hollow- gravity load lateral load core frame panels frame 40 + 30 + 40 = 110 ft (33.5 m) wall inverted column L-beam T-beam N 4 story building, high seismicity 6 story building, high seismicity 10 story building, high seismicity 6 story building, medium seismicity

FULLY POST-TENSIONED WALLS 133 ft (41 ft) 81 ft 81 ft (25 ft) (25 ft) 55 ft (17 ft) 20 ft (6 m) 20 ft (6 m) 26 ft (8 m) 20 ft (6 m) 4 story high seismicity 6 story high seismicity 10 story high seismicity 6 story medium seismicity

FULLY POST-TENSIONED WALLS C L C L #3 spirals Ap=1.49in2 (961mm2) #3 spirals Ap=1.49in2 (961mm2) rsp=7.3% fpi=0.60-0.65fpu rsp=7.3% fpi=0.60-0.65fpu 12in. 12in. (305mm) (305mm) 10 ft (3 m) 10 ft (3 m) Wall PH4 Wall PH6 C L C L #3 spirals Ap=1.49in2 (961mm2) #3 spirals Ap=1.49in2 (961mm2) rsp=7.3% fpi=0.60-0.65fpu rsp=1.8% fpi=0.625fpu 12in. 12in. (305mm) (305mm) 13 ft (4 m) 10 ft (3 m) Wall PH10 Wall PM6

EMULATIVE WALLS Wall EH4 Wall EH6 Wall EH10 Wall EM6 No. 8 bars 16 pairs 5 pairs C 15 pairs 5 pairs L C L @ 2.25 in. @ 18 in. @ 2.5 in. @ 18 in. (@ 57 mm) (@ 457 mm) (@ 63 mm) (@ 457 mm) 12in. 12in. (305mm) (305mm) 10 ft (3 m) 10 ft (3 m) Wall EH4 Wall EH6 No. 8 bars No. 5 bars No. 6 bars No. 5 bars 20 pairs 6 pairs C 7 pairs 5 pairs L C L @ 2.25 in. @ 18 in. @ 5.25 in. @ 18 in. (@ 57 mm) (@ 457 mm) (@ 133 mm) (@ 457 mm) 12in. 12in. (305mm) (305mm) 13 ft (4 m) 10 ft (3 m) Wall EH10 Wall EM6

PARTIALLY POST-TENSIONED WALLS No. 5 bars No. 5 bars No. 8 bars No. 5 bars 7 pairs 5 pairs C L 7 pairs 5 pairs C L @ 5.5 in. @ 18 in. @ 5.5 in. @ 18 in. (@ 140 mm) (@ 457 mm) (@ 140 mm) (@ 457 mm) 12in. 12in. (305mm) (305mm) 10 ft (3 m) 10 ft (3 m) Wall HH6-25 Wall HH6-50 No. 8 bars No. 5 bars No. 5 bars 11 pairs 5 pairs C L 8 pairs C L @ 3.5 in. @ 18 in. @ 17 in. (@ 89 mm) (@ 457 mm) (@ 432 mm) 12in. 12in. (305mm) (305mm) 10 ft (3 m) 10 ft (3 m) Wall HH6-75 Wall HM6-50

ANALYTICAL WALL MODEL truss element fiber element kinematic constraint stress, ksi (MPa) 100 (690) truss element MILD STEEL -100 (690) -0.08 0.08 fiber element strain stress, ksi (MPa) stress, ksi (MPa) 7 (48) 160 (1103) 120 (827) kinematic constraint strain 0.0351 strain 0.006 PT STEEL CONCRETE

WALL BEHAVIOR UNDER MONOTONIC LOADS base shear, kips (kN) base shear, kips (kN) 1500 1000 (6672) (4448) Wall PH6 Wall HH6-25 Wall HH6-50 Wall PH4 Wall HH6-75 Wall EH4 Wall EH6 3 roof drift, % roof drift, % 3 base shear, kips (kN) base shear, kips (kN) 1000 500 (4448) (2224) Wall PM6 Wall PH10 Wall HM6-50 Wall EH10 Wall EM6 3 2 roof drift, % roof drift, %

SIX STORY WALLS IN HIGH SEISMICITY base shear, kips (kN) base shear, kips (kN) base shear, kips (kN) 1000 Wall HH6-25 Wall HH6-50 (4448) Wall PH6 (-4448) -1000 -3 3 -3 3 -3 3 roof drift, % roof drift, % roof drift, % base shear, kips (kN) base shear, kips (kN) 1000 1000 (4448) Wall HH6-75 (4448) Wall EH6 (-4448) (-4448) -1000 -1000 -3 3 -3 3 roof drift, % roof drift, %

NORMALIZED INELASTIC ENERGY DISSIPATION base shear, kips (kN) 1000 (4448) Dh ksec -Dc Dh dh = -Dc Ue Ue (-4448) -1000 -3 3 roof drift, %

NORMALIZED INELASTIC ENERGY DISSIPATION (dh = Dh / Ue) (dh = Dh / Ue) 2 2 Wall PH4 Wall PH6 Wall EH4 Wall HH6-25 1.5 1.5 Wall HH6-50 Wall HH6-75 Wall EH6 1 1 0.5 0.5 cycle roof drift, % 3 cycle roof drift, % 3 (dh = Dh / Ue) (dh = Dh / Ue) 2 2 Wall PH10 Wall PM6 Wall EH10 Wall HM6-50 1.5 1.5 Wall EM6 1 1 0.5 0.5 3 cycle roof drift, % cycle roof drift, % 2

DYNAMIC RESPONSE roof drift, % roof drift, % 2.5 2.5 PH4 NOSY PH6 EH4 PGA=0.97g HH6-25 HH6-50 NOSY HH6-75 PGA=0.97g EH6 -2.5 -2.5 15 15 time, seconds time, seconds roof drift, % roof drift, % 2.5 1.5 PH10 NOSY EH10 PGA=0.39g PM6 NOSY HM6-50 PGA=0.97g EM6 -2.5 -1.5 15 15 time, seconds time, seconds

REDUCTION IN MAXIMUM ROOF DRIFT normalized maximum roof drift 1.0 0.8 0.6 0.4 PH6 HH6-25 HH6-50 HH6-75 EH6 0.2 average 0.2 0.4 0.6 0.8 1 normalized mild steel ratio

REDUCTION IN NUMBER OF DRIFT PEAKS average number of drift peaks average number of drift peaks 8 8 WALL PH4 WALL PH6 WALL EH4 WALL HH6-25 6 6 WALL HH6-50 WALL HH6-75 4 4 WALL EH6 2 2 0.5 1 0.5 1 normalized amplitude of drift peak normalized amplitude of drift peak average number of drift peaks average number of drift peaks 8 8 WALL PH10 WALL PM6 6 WALL EH10 6 WALL HM6-50 WALL EM6 4 4 2 2 0.5 1 0.5 1 normalized amplitude of drift peak normalized amplitude of drift peak

OUTLINE Prototype walls Expected behavior Seismic design approach and evaluation Summary and conclusions

FIRST MODE REPRESENTATION -1.5 1.5 4 8 12 16 time, seconds roof drift, % first mode total Wall HW1 SAC LA25, PGA=0.87g

SDOF REPRESENTATION MDOF MODEL SDOF MODEL base shear, kips (kN) 2000 2000 (8896) (8896) (8896) (8896) -2000 -2000 -3 3 -3 3 roof drift, % roof drift, % F akbe F F akbe [(1+br)Fbe,Dbe] (Fbe,Dbe) (brFbe,Dbe) D D D = + kbe (1+bs)kbe bskbe Bilinear-Elastic/ Bilinear-Elastic (BE) Elasto-Plastic (EP) Elasto-Plastic (BP)

SAC GROUND MOTIONS pseudo-acceleration, g 4 Los Ang., SD soil, survival-level (SAC LA21-40) AVG spectrum 2 5% damping 0.5 1 1.5 2 2.5 3 3.5 period, seconds

SDOF/MDOF PEAK DISPLACEMENT SDOF/MDOF maximum displacement ratio 1.2 1.0 mean 0.8 0.6 0.4 Wall HW1 SAC LA21- 40 0.2 50 100 (381) 150 maximum incremental velocity, in/sec (cm/sec)

DUCTILITY DEMAND (Farrow and Kurama, 2001) F akbe F F akbe [(1+br)Fbe,Dbe] (Fbe,Dbe) (brFbe,Dbe) D D D = + kbe (1+bs)kbe bskbe Bilinear-Elastic/ Bilinear-Elastic (BE) Elasto-Plastic (EP) Elasto-Plastic (BP) bs = br = 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) (Farrow and Kurama, 2001)

DUCTILITY DEMAND SPECTRA (Farrow and Kurama, 2001) 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 BP, mean regression 3.5 3.5 period, seconds period, seconds 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, seconds period, seconds

NONLINEAR DEMAND SPECTRA demand acceleration, g demand acceleration, g 1.5 1.5 T = 0.5 sec. m=1 m=1 T = 1.5 sec. a = -0.71 a = -0.71 b = 0.94 b = 0.94 1 1 (linear-elastic) (linear-elastic) 2 a = 2.3 2 1.5 m = demand 1 a = 2.3 b = 1.3 T = 0.5 sec. 1.5 m = 1 T = 1.5 sec. a 1 spectrum b = 1.3 S (g) 0.5 B 2 C 4 S (g) 0.5 a 1 2 8 4 capacity curve 8 F D E 20 40 S (cm) d 60 80 100 (a) 20 40 S (cm) d 60 80 100 4 0.5 1.5 m = 1 1.5 4 b = 0.94 a = -0.71 T = 0.5 sec. 0.5 m = 1 b = 0.94 T = 1.5 sec. a = -0.71 S (g) a 1 A 0.5 B 2 1 2 C 4 8 S (g) 0.5 a 4 8 E D 20 40 S (cm) 60 80 100 20 F 40 S (cm) 60 80 100 d (b) d 8 8 (39) 100 (39) 100 demand displacement, cm (in.) demand displacement, cm (in.)

DESIGN OBJECTIVES – SURVIVAL LEVEL base shear immediate occupancy (Dt=1.19%) collapse prevention (Dt=2.17%) WALL WH1 WALL WH2 roof drift

WALLS HW1 AND HW2 Wall WH1 Wall WH2 No. 10 bars No. 5 bars C 8 pairs @ 2.5 in. @ 18 in. (@ 63 mm) (@ 457 mm) 12in. (305mm) 11 ft (3.35 m) Wall WH1 No. 10 bars No. 5 bars C 7 pairs 6 pairs L @ 2.5 in. @ 18 in. (@ 63 mm) (@ 457 mm) 12in. (305mm) 10 ft (3 m) Wall WH2

WALL HW1 maximum roof drift, % 3 2 Dt=1.19% 1 Dmean=1.13% 50 100 (381) 150 maximum incremental velocity, in/sec (cm/sec)

WALL WH2 maximum roof drift, % 3.5 3 2.5 Dt=2.17% 2 Dmean=1.85% 1.5 1 0.5 50 100 (381) 150 maximum incremental velocity, in/sec (cm/sec)

CONCLUSIONS Energy Dissipation Mild steel reinforcement yielding in tension and compression Design Approach MDOF SDOF Nonlinear demand spectra Target drift Seismic Response Evaluation Maximum drift reduced below target drift Significant scatter in results

National Science Foundation CAREER-Program CMS 98-74872 Program Directors Dr. S. C. Liu Dr. S. MaCabe