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DESIGN OF LARGE OPENINGS IN UNBONDED POST-TENSIONED PRECAST CONCRETE WALLS

DESIGN OF LARGE OPENINGS IN UNBONDED POST-TENSIONED PRECAST CONCRETE WALLS. Michael G. Allen Yahya C. Kurama University of Notre Dame Notre Dame, IN. PCI Committee Days, Chicago, Illinois, April 14-15, 2000. 1998 PCI Daniel P. Jenny Research Fellowship University of Notre Dame. ELEVATION.

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DESIGN OF LARGE OPENINGS IN UNBONDED POST-TENSIONED PRECAST CONCRETE WALLS

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  1. DESIGN OF LARGE OPENINGS IN UNBONDED POST-TENSIONED PRECAST CONCRETE WALLS Michael G. Allen Yahya C. Kurama University of Notre Dame Notre Dame, IN PCI Committee Days, Chicago, Illinois, April 14-15, 2000

  2. 1998 PCI Daniel P. Jenny Research FellowshipUniversity of Notre Dame

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

  4. GAP OPENING BEHAVIOR gap

  5. UNDER LATERAL LOADS AT FAILURE compression stresses shear stresses

  6. 3 3 CRACKING 5 2 1 4 3 2 5

  7. RESEARCH OBJECTIVES • Develop analytical model • Conduct parametric investigation • Develop design approach

  8. FINITE ELEMENT MODEL nonlinear plane stress elements truss elements contact elements

  9. GAP OPENING

  10. STAGES OF RESPONSE • Gravity and post-tensioning only • Lateral loads

  11. UNDER GRAVITY AND POST-TENSIONING ONLY Asf

  12. DESIGN PREDICTION C T C

  13. Asf (predicted/ABAQUS)ALL CASES 1.5 1.0 lp=10 feet (fci=0.68 ksi) lp=20 feet (fci=1.48 ksi) lp=15 feet (fci=0.44 ksi) 0.5 lp=20 feet (fci=0.67 ksi) lp=15 feet (fci=0.68 ksi) lp=20 feet (fci=0.34 ksi) lp=20 feet (fci=0.68 ksi) 0 2.0 4.0 ho/lo

  14. UNDER LATERAL LOADS AT FAILURE xcr compression stresses shear stresses Tmax

  15. CRITICAL SECTION xcr

  16. LARGE OPENING VERSUS SMALL OPENINING xcr xcr large opening small opening

  17. PANEL REGION TO BE ANALYZED xcr

  18. FREE BODY DIAGRAM Ntop Ngrav Vtop V1 Ncr Mcr Vlc Nlc Mlc

  19. FREE BODY DIAGRAM

  20. MOMENT AT CRITICAL SECTION, Mcr M / Mcr 8 ho/hp = 0.125 0 Mlc V1 Nlc Vtop Ngrav Vlc Ntop -8 0.5 0 0.25 lo/lp

  21. M / Mcr 8 ho/hp = 0.375 0 -8 0.5 0 0.25 lo/lp MOMENT AT CRITICAL SECTION Mlc V1 Nlc Vtop Ngrav Vlc Ntop

  22. M / Mcr 8 lo/lp = 0.1 0 -8 0.5 0 0.25 ho/hp MOMENT AT CRITICAL SECTION Mlc V1 Nlc Vtop Ngrav Vlc Ntop

  23. MOMENT AT CRITICAL SECTION M / Mcr lo/lp = 0.4 8 V1 Vtop Vlc 0 Mlc Nlc Ngravity Ntop -8 0.5 0 0.25 ho/hp

  24. PREDICTED VERSUS ACTUAL MOMENT lo/lp = 0.3 Mcr (104 kip-in) 0 -1 Vtop Mcr ABAQUS (Vtop) -2 Ncr predicted (Vtop) ABAQUS (Vlc) predicted (Vlc) Vlc -3 0.5 0 0.25 ho/hp

  25. PREDICTED VERSUS ACTUAL MOMENT Mcr (104 kip-in) ho/hp = 0.25 0 -1 ABAQUS (Vtop) -2 predicted (Vtop) ABAQUS (Vlc) predicted (Vlc) -3 0.5 0 0.25 lo/lp

  26. PREDICTED VERSUS ACTUAL MOMENT Mcr (104 kip-in) 3 ho/hp = 0.25 ABAQUS (Mlc) predicted (Mlc) ABAQUS (Ntop) 2 predicted (Ntop) 1 0 0.5 0.25 lo/lp

  27. PREDICTED VERSUS ACTUAL MOMENT Mcr (104 kip-in) 3 lo/lp = 0.3 ABAQUS (Mlc) predicted (Mlc) ABAQUS (Ntop) 2 predicted (Ntop) 1 0 0.5 0.25 ho/hp

  28. TOTAL Mcr Mcr (104 kip-in) ho/hp = 0.375 3 ABAQUS predicted 2 1 0 0.5 0.25 lo/lp

  29. TOTAL Mcr Mcr (104 kip-in) lo/lp = 0.3 3 ABAQUS predicted 2 1 0 0.5 0.25 ho/hp

  30. TOTAL Ncr Ncr (kip) ho/hp = 0.25 400 0 ABAQUS predicted -400 0.5 0 0.25 lo/lp

  31. TOTAL Ncr Ncr (kip) lo/lp = 0.3 400 0 ABAQUS predicted -400 0.5 0 0.25 ho/hp

  32. Asf IN TOP CHORD Asf (in2) ho/hp = 0.25 6 3 ABAQUS predicted 0 0.5 0.25 lo/lp

  33. Asf IN TOP CHORD Asf (in2) lo/lp = 0.3 6 3 ABAQUS predicted 0 0.5 0.25 ho/hp

  34. Asf (predicted/ABAQUS)TOP CHORD 3 2 1 0 1.5 3 ho/lo

  35. Asf IN LEFT CHORD Asf (in2) 6 ho/hp = 0.25 3 ABAQUS predicted 0 0.5 0.25 lo/lp

  36. Asf IN LEFT CHORD

  37. Asf IN MIDDLE CHORD Asf (in2) 6 lo/lp = 0.3 3 ABAQUS predicted 0 0.5 0.25 ho/hp

  38. Asf (predicted/ABAQUS)LEFT CHORD 3 1.5 0 1.5 3 ho/lo

  39. CONCLUSIONS Analytical Model • ABAQUS model developed for walls with openings • ABAQUS results compare well with DRAIN-2DX results and closed form results Parametric Investigation • Gravity and post-tensioning loads only • As fci increases, steel requirement increases significantly • As ho increases, steel requirement decreases, especially for longer walls • As lo increases, steel requirement increases, especially for shorter walls

  40. CONCLUSIONS Design Approach • Utilizes a strut-and-tie model • Can be used to predict the ABAQUS results; and • To design the reinforcement above the openings • Asc to prevent cracking • Asf to minimize crack widths

  41. REMAINING WORK • Finish design for lateral loads • Experimental verification (Lehigh Tests)

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