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Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A

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Presentation on theme: "Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A"— Presentation transcript:

1 Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A
UNBONDED POST-TENSIONING: SEISMIC APPLICATIONS IN CONCRETE STRUCTURAL WALLS Yahya C. Kurama University of Notre Dame Notre Dame, Indiana, U.S.A Tokyo Institute of Technology Yokohama, Japan August 16, 2000

2 anchorage wall panel unbonded PT steel horizontal joint spiral
ELEVATION anchorage wall panel unbonded PT steel horizontal joint spiral reinforcement foundation

3 LATERAL DISPLACEMENT precast wall gap opening shear slip

4 BEHAVIOR UNDER LATERAL LOAD
base shear, kips (kN) 800 (3558) concrete crushing (failure) PT bar yielding (flexural capacity) effective linear limit (softening) gap opening (decompression) roof drift, % 1 2

5 BONDED VERSUS UNBONDED BEHAVIOR
wall unbonded wall

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

7 Unbonded post-tensioned precast walls without supplemental damping
OUTLINE Unbonded post-tensioned precast walls without supplemental damping with supplemental damping Unbonded post-tensioned hybrid coupled walls

8 UNBONDED POST-TENSIONED WALLS WITHOUT SUPPLEMENTAL ENERGY DISSIPATION Analytical Modeling

9 ANALYTICAL MODEL node truss element constraint fiber element wall model cross-section

10 BEAM-COLUMN SUBASSEMBLAGE TESTS
NIST (1993) N H upper crosshead 7.5 ft (2.3 m) 4.3 ft (1.3 m) lower crosshead

11 MEASURED VERSUS PREDICTED RESPONSE
lateral load, kips (kN) 50 measured (NIST) predicted drift, % -6 6 -50 (222) El-Sheikh et al. 1997

12 FINITE ELEMENT (ABAQUS) MODEL
nonlinear plane stress elements truss elements contact elements

13 GAP OPENING

14 FINITE ELEMENT VERSUS FIBER ELEMENT
base shear, kips (kN) 1000 (4448) yielding state 500 gap opening state finite element fiber element 0.5 1 1.5 2 2.5 roof drift, %

15 Seismic Design and Response Evaluation

16 immediate occupancy collapse prevention base shear design
DESIGN OBJECTIVES immediate occupancy collapse prevention base shear design level gr. mt. survival level gr. mt. roof drift

17 BUILDING LAYOUT FOR HIGH SEISMICITY
8 x 24 ft = 192 ft (60 m) gravity load frame hollow- core panels lateral load frame wall N 110 ft (35 m) S inverted T-beam column L-beam

18 C L PT bars ap=1.5 in2 (9.6 cm2) #3 spirals fpi=0.60fpu rsp=7% 12 in
WALL WH1 CROSS SECTION C L PT bars ap=1.5 in2 (9.6 cm2) fpi=0.60fpu #3 spirals rsp=7% 12 in (31 cm) 10 ft (3 m) half wall length

19 ROOF-DRIFT TIME-HISTORY
4 2 -2 Hollister (survival) unbonded PT precast wall cast-in-place RC wall -4 10 20 30 time, seconds

20 WALLS WITH SUPPLEMENTAL ENERGY DISSIPATION
U.S. National Science Foundation CMS CAREER Program

21 viscous damper diagonal brace bracing column floor slab wall
VISCOUS DAMPED WALLS viscous damper diagonal brace bracing column floor slab wall

22 bracing diagonal viscous column brace damper wall panel gap
DAMPER DEFORMATION bracing column diagonal brace viscous damper wall panel gap

23 damper deformation, in (cm)
6 compression tension 5 4 at yielding state Dllp=0.84% floor 3 2 1 -2 (-5) -1 1 2 (5) damper deformation, in (cm)

24 SURVIVAL LEVEL GROUND MOTION
DESIGN OBJECTIVE base shear SURVIVAL LEVEL GROUND MOTION damped system undamped system roof drift

25 spectral displacement Sd , in (cm)
DAMPER DESIGN - WALL WH1 Sa, g 3 Dllp=0.84% MIV=67 in/sec (171 cm/sec) Te = 0.64 sec. xev=3% 2 Teff=0.80 sec. 10% xr=22% 15% 23% 1 30% 40% X 4 8 12 16 (41) spectral displacement Sd , in (cm)

26 ROOF DRIFT TIME HISTORY - WALL WH1
3 damped Newhall, 0.66g undamped Dllp=0.84% Dllp=0.84% -3 20 time, seconds

27 MAXIMUM ROOF DRIFT - WALL WH1
Dmax, % 7 undamped wall damped wall Dllp= 0.84% 0.4 0.8 1.2 peak ground acceleration PGA, g

28 MAXIMUM ROOF DRIFT - WALL WP1
Dmax, % 7 undamped wall damped wall Dllp= 1.14% 0.4 0.8 1.2 peak ground acceleration PGA, g

29 MAXIMUM ROOF DRIFT - WALL WP2
Dmax, % 7 undamped wall damped wall Dllp= 1.47% 0.4 0.8 1.2 peak ground acceleration PGA, g

30 MAXIMUM ROOF ACCELERATION - WALL WH1
amax, g 0.5 1 1.5 2 0.4 0.8 1.2 peak ground acceleration PGA, g undamped wall damped wall

31 UNBONDED POST-TENSIONED HYBRID COUPLED WALL SYSTEMS
U.S. National Science Foundation CMS U.S.-Japan Cooperative Program on Composite and Hybrid Structures

32 EMBEDDED STEEL COUPLING BEAM
embedment region steel beam

33 TEST RESULTS FOR EMBEDDED BEAMS
Harries et al.1997

34 POST-TENSIONED COUPLING BEAM
PT anchor connection region wall region beam PT steel angle embedded plate PT steel

35 DEFORMED SHAPE contact region gap opening

36 COUPLING FORCES Vcoupling P z db P lb Vcoupling P z Vcoupling = lb

37 RESEARCH ISSUES Force/deformation capacity of beam-wall connection region beam angle Yielding of the PT steel Energy dissipation Self-centering Overall/local stability

38 truss element kinematic constraint fiber element fiber element
ANALYTICAL WALL MODEL wall beam wall truss element kinematic constraint fiber element fiber element

39 BEAM-WALL SUBASSEMBLAGE
F L8x8x3/4 W18x234 PT strand lw = 10 ft lb = 10 ft (3.0 m) lw = 10 ft fpi = fpu ap = 1.28 in2 (840 mm2)

40 MOMENT-ROTATION BEHAVIOR
moment Mb, kip.ft (kN.m) 2500 (3390) Mp My 1250 ultimate PT-yield softening decompression 2 4 6 8 10 rotation qb, percent

41 CYCLIC LOAD BEHAVIOR moment Mb, kip.ft (kN.m) -10 -5 5 10 -2500 2500
5 10 -2500 2500 (3390) rotation qb, percent monotonic cyclic

42 ap and fpi (Pi = constant)
4 8 10 2500 (3390) moment Mb, kip.ft (kN.m) rotation qb, percent 2 6 1250

43 PT STEEL AREA 4 8 10 2500 (3390) moment Mb, kip.ft (kN.m)
4 8 10 2500 (3390) moment Mb, kip.ft (kN.m) rotation qb, percent 1250 2 6

44 TRILINEAR ESTIMATION 4 8 10 1250 2500 (3390) ultimate PT-yield
4 8 10 1250 2500 (3390) ultimate PT-yield softening smooth relationship trilinear estimate moment Mb, kip.ft (kN.m) rotation qb, percent 2 6

45 W18x234 ap = 0.868 in2 (560 mm2) fpi = 0.7 fpu PROTOTYPE WALL 82 ft
12 ft ft ft 82 ft (24.9 m) fpi = 0.7 fpu (3.7m 2.4m 3.7 m)

46 COUPLING EFFECT 1 2 3 4 roof drift, percent 40000 80000 120000
1 2 3 4 roof drift, percent 40000 80000 120000 (162720) base moment, kip.ft (kN.m) coupled wall two uncoupled walls

47 Beam-wall connection subassemblages Ten half-scale tests
EXPERIMENTAL PROGRAM Beam-wall connection subassemblages Ten half-scale tests Objectives Investigate beam M-q behavior Verify analytical model Verify design tools and procedures

48 ELEVATION VIEW (HALF-SCALE)
L4x7x3/8 W10X100 PT strand strong floor lw = 5 ft lb = 5 ft (1.5 m) lw = 5 ft fpi = 0.7 fpu ap = in2 (140 mm2)

49 Large self-centering capability Softening, thus, period elongation
CONCLUSIONS Unbonded post-tensioning is a feasible construction method for reinforced concrete walls in seismic regions Large self-centering capability Softening, thus, period elongation Small inelastic energy dissipation Need supplemental energy dissipation in high seismic regions

50


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