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PCI 124 Application Handout.pdf

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PCI 124 Application Handout.pdf

  1. 1. PCI 124 Specification For Fire Resistance Of Precast/Prestressed Concrete SPEAKER INFO Slides to be omitted for 60-min virtual presentation Slides modified by Matt
  2. 2. NCEES REGISTERED PROGRAM PCI has met the standards and requirements of the Registered Continuing Education Program (RCEP) of the National Council of Examiners for Engineers & Surveyors (NCEES). Credit earned on completion of this program will be reported to RCEP. A certificate of completion will be issued to each participant. As such, it does not include content that may be deemed or construed to be an approval or endorsement by NCEES or RCEP. 2
  3. 3. LEARNING OBJECTIVES PCI 124 SPECIFICATION FOR FIRE RESISTANCE • Review evolution history for fire resistance design of precast/prestressed concrete in PCI 124. • Examine the format of PCI 124. • Review examples using the Prescriptive- based provisions of PCI 124. • Review examples using the Rational Design-based provisions of PCI 124. • Review special considerations for poke- throughs and connections of precast
  4. 4. EVOLUTION OF PCI 124 PCI 124 SPECIFICATION FOR FIRE RESISTANCE 4
  5. 5. PCI 124 SPECIFICATION FOR FIRE RESISTANCE • 1960s – PCI develops procedures for calculated fire resistant design of precast. • 1977 – PCI publishes the first edition of design manual for precast. • ICBO issues Evaluation Report 3264 to accept the 1977 edition as alternate method in UBC • 2000 – 1st Edition of IBC includes MNL 124-77 for precast prestressed slabs. EVOLUTION OF PCI 124 5
  6. 6. • IBC 703.3 Alternate Methods • Documented fire resistance designs • Prescriptive Design – Section 719 • Calculation Method – Section 720 • Engineering Comparisons - ASTM E119 • Alternate Means – IBC 104.11 2000 INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 6
  7. 7. • IBC 720.2.3.1 Slab cover • Minimum cover to positive moment reinforcement • IBC Table 720.2.3(2) - precast • MNL 124 as alternate for precast prestressed slabs 2000 INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 7
  8. 8. IBC 104.11 Alternate Materials, Designs and Methods • Documented alternate materials, design and methods • Code alternatives proposed for approval • Research reports and supporting data • Testing where necessary INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 8
  9. 9. • IBC 104.11 Means • Evaluation reports – ESR 1997 INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 9
  10. 10. • PCI becomes SDO – 2014 (Standards Development Organization) • PCI Standards Committee established. • PCI Fire Committee assigned revisions • MNL 124 revised into mandatory language. • Designated PCI 124 • Final approval October 2019 INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 10
  11. 11. • PCI 124 becomes approved method in 2021 IBC • Section 722.1 1. Concrete/Masonry – ACI 216.1 2. Precast Concrete – PCI 124 3. Steel – Chapter 5 of ASCE 29 4. Wood – Chapter 16 – AWC-NDS 2021 INTERNATIONAL BUILDING CODE EVOLUTION OF PCI 124 11
  12. 12. • Chapter 1 - General • Scope – Precast & Cast-in-place • Definitions • Notations • Referenced Standards SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 FORMAT 12
  13. 13. • Chapter 2 - General • Steel properties • Concrete properties • Restrained/unrestrained • Methods for fire resistance • Prescriptive Fire-Resistance • Rational Design SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 FORMAT 13
  14. 14. • Chapter 3 - Precast Concrete • General • Prescriptive requirements – columns, beams, slabs & walls • Rational design – slabs/beams SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 FORMAT 14
  15. 15. • Chapter 4 - Special Considerations • Protection of openings • Protection of connections • Appendix - Commentary SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 FORMAT 15
  16. 16. • Section 2.4 Determining Restrained/Unrestrained Conditions • 2.4.1 Precast considered restrained when building frame resists thermal expansion of floor/roof elements • Unrestrained if not meeting 2.4.1 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 16
  17. 17. • Section 3.2 Prescriptive Requirements • Precast Columns • Steel Columns with Precast Covers • Precast Walls (solid, hollow-core, ribbed) • Precast Beams • Precast Floor/Roof Slabs SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 17
  18. 18. • Section 3.2.1 Precast Columns • Precast Columns - f’c < 12,000 psi • Table 3.2.1 - Minimum column dimension • Section 3.2.1.2 – Minimum main longitudinal reinforcement cover SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 18
  19. 19. • Section 3.2.1 Precast Columns • Precast Columns - f’c < 12,000 psi SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 19
  20. 20. • Section 3.2.1 Precast Columns • Precast Columns - f’c > 12,000 psi • All concrete types & fire resistances 24‐in min 24‐in min SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 20
  21. 21. • Section 3.2.1 Precast Columns • Section 3.2.1.2 – Minimum Reinforcement Cover (all columns) • All Main Longitudinal Reinforcement • Minimum 1-inch per 1-hour fire resistance • Maximum cover 2-inches Columns Cover SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 21
  22. 22. • Section 3.2.1 Precast Columns • Section 3.2.1.2 – Minimum Reinforcement cover for columns - f’c > 12,000 psi • Spiral/Tie Reinforcement • Free ends of rectangular ties terminate with 135-degree standard hook • Free ends of circular ties terminate with 90-degree standard hook • Free ends of spirals/lap splices terminate with 90-degree standard hook • Hook extensions @ 6 bar diameters, min 3” • Hook extensions directed to column core SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 22
  23. 23. • Section 3.2.2 Precast Walls • Section 3.2.2.1 – Solid wall panels SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE Table 3.2.2(c) Multi-course solid wall panels 23
  24. 24. • Section 3.2.2 Precast Walls • Section 3.2.2.3 – Non-uniform wall panels • Hollow-core – equivalent thickness Equivalent Thickness = Net cross-sectional concrete area (neglect shaded area) Nominal panel width • Use Equivalent Thickness with Table 3.2.2(a) • Cores filled with expanded shale/clay/slate or vermiculite/perlite – Use panel thickness SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 24
  25. 25. • Section 3.2.2 Precast Walls • Section 3.2.2.3 – Non-uniform wall panels • If t < s/4, Equivalent Thickness = t t s SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 25
  26. 26. • Section 3.2.2 Precast Walls • Section 3.2.2.3 – Non-uniform wall panels • If t > s/2 Equivalent thickness = Net Cross-sectional concrete area (neglect shaded area) Nominal panel width SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 26
  27. 27. • Section 3.2.2 Precast Walls • Section 3.2.2.3 – Non-uniform wall panels If s/2 > t > s/4 use the following equation te = t + (4t/s – 1)(Te – t) EQ (3.2.2-1) Where Te = Net Cross-sectional concrete area (neglect shaded area) Nominal panel width SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 27
  28. 28. • Section 3.2.2 Precast Walls • Section 3.2.2.3.3 – Non-uniform tapered panels • Equivalent thickness at the lesser of the following distances: • 2t from thinnest portion of panel, • Or 6-inches from thinnest portion of panel SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 28
  29. 29. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 FORMAT 29
  30. 30. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels • Based on following equation and Figure 3.2(e) R = (R1 0.59 + R2 0.59 + …….. Rn 0.59)1.7 Eq (3.2.2.4‐1) Where Rn 0.59 is the value for the specific fire resistant component from Figure 3.2(e) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 30
  31. 31. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels • Based on equation and Figure 3.2(e) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 31
  32. 32. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels • Based on equation and Figure 3.2(e) Insulated Wall: • Outer wythe – 2.5‐in. Sil. Agg. • R1 0.59 = 8.0 • Inner wythe – 2‐in. Sil. Agg. • R2 0.59 = 6.75. • Core – 1‐in foam plastic, R3 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 32
  33. 33. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels • Based on equation and Figure 3.2(e) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 33
  34. 34. • Section 3.2.2 Precast Walls • Section 3.2.2.3.4 – Insulated panels • Based on following equation and Figure 3.2(e) R = (R1 0.59 + R2 0.59 + …….. Rn 0.59)1.7 Eq (3.2.2.4‐1) R = (8.0 + 6.75 + 2.57)1.7 ≈ 127 min. → 2.0+ hours Outer Wythe Inner Wythe Insulated Core SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 34
  35. 35. • Section 3.2.3 Precast Beams • Section 3.2.3.1 – Restrained beam reinforcement concrete cover • Table 3.2.3(a) – Restrained prestressed beams 8-inches or greater width • Table 3.2.3(b) – Restrained prestressed beams all widths • Table 3.2.3(c) – Restrained nonprestressed beams SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 35
  36. 36. • Section 3.2.3 Precast Beams • Section 3.2.3.1 – Restrained beam reinforcement concrete cover SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 36
  37. 37. • Section 3.2.3 Precast Beams • Section 3.2.3.2 – Unrestrained beam reinforcement concrete cover • Table 3.2.3(d) – Unrestrained 8-inches or greater beams • Table 3.2.3(e) – Unrestrained beams all widths • Table 3.2.3(f) – Unrestrained nonprestressed beams SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 37
  38. 38. • Section 3.2.3 Precast Beams • Section 3.2.3.2 – Unrestrained beam reinforcement concrete cover – Table 3.2.3(d) for beams > 8-inches. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 38
  39. 39. • Section 3.2.3 Precast Beams • Section 3.2.3.2 – Unrestrained beam reinforcement concrete cover – Table 3.2.3(e) for beams all widths. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 39
  40. 40. • Table 3.2.3(e) Precast Beams All Widths • Area calculation for stemmed members SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 40
  41. 41. • Table 3.2.3(e) Precast Beams All Widths Area = A-stem + A-Flange (up to 3 X average stem width) Average stem width = (4.5 + 6.5)/2 = 5.5 in. Area stem = 26-in X 5.5-in = 143- in.2 Flange width = 3 X 5.5-in = 16.5 in. Area flange = 4-in X 16.5 in. = 66-in.2 . Total Area = 143-in.2 + 66-in.2 = 209-in.2 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 41
  42. 42. • Section 3.2.3 Precast Beams • Section 3.2.3.2 – Unrestrained beam reinforcement concrete cover – Table 3.2.3(e) for beams all widths. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 42
  43. 43. • Section 3.2.3 Precast Beams • Section 3.2.3.3.1 – Prestressing tendon cover in beams. a) Individual tendon • Surface of tendon to fire face of beam b) Ungrouted duct • Surface of duct to fire face of beam c) Multiple tendons • Average minimum distance from tendon surfaces to fire face of beam SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 43
  44. 44. • Section 3.2.3 Precast Beams • Section 3.2.3.3.1 – Prestressing tendon cover in beams (cont’d). d) Corner tendon (equally spaced) • D/2 from surface of tendon to fire face of beam SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 44
  45. 45. • Section 3.2.3 Precast Beams • Section 3.2.3.3.1 – Prestressing tendon cover in beams (cont’d). e) Stemmed members – multiple vertical tendons located along a vertical line • Average distance from centroid of tendons to bottom of stem. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 45
  46. 46. • Section 3.2.3 Precast Beams • Section 3.2.3.3.1 – Prestressing tendon cover in beams (cont’d). f) Any one tendon – min. of 1-in. and not less than 1/2 of smaller values in Tables 3.2.3(a), 3.2.3(b), 3.2.3(d), or 3.2.3(e). SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 46
  47. 47. • Section 3.2.3 Precast Beams • Section 3.2.3.3.2 – Nonprestressed reinforcement cover in beams. a) Individual bars - Surface of bar to fire face of beam b) Corner bars - D/2 from surface of bar to fire face of beam SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 47
  48. 48. • Section 3.2.3 Precast Beams • Section 3.2.3.3.2 – Nonprestressed reinforcement cover in beams (cont’d). c) One bar – minimum. of 3/4-in. and not less than 1/2 of smaller values in Tables 3.2.3(c) or 3.2.3(f). SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 48
  49. 49. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.1 – Solid single-course slabs – Use Table 3.2.2 (a) for walls. • Nonuniform thick slabs – Use Equivalent Thickness methods for walls in 3.2.2.3 Thickness Slabs SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 49
  50. 50. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.1.2 – Solid single-course slabs with 5/8-inch gypsum board on underside – Fig. 3.2.4(a) Thickness Slabs 5/8-Type X Gyp Board Aggregate type SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 50
  51. 51. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.2 – Multi-course floor slabs Figures 3.2.4(b), 3.2.4(c) or 3.2.4(d) Multi-Course Floor Slabs Layer Thickness Lt-Wt. Conc. Normal. Wt. Conc. Fig. 3.2(b) Layer Thickness Cellular/Perlite/Vermiculite Normal Wt. Conc. Fig. 3.2(d) Concrete VCF/SMF/IM Layer Thickness Fig. 3.2(c) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 51
  52. 52. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.2 – Multi-course floor slabs Figure 3.2.4(b) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 52
  53. 53. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.2 – Multi-course floor slabs Figures 3.2.4(c) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 53
  54. 54. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.3 – Multi-course roof slabs – Fig. 3.2.4(e) Fig. 3.2.4(e) Multi-Course Roof Slabs Layer Thickness Mineral Board Normal. Wt. Conc. Layer Thickness Glass Fiber Board Normal Wt. Conc. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 54
  55. 55. • Section 3.2.4 Precast Floors/Roofs • Section 3.2.4.3 – Multi-course roof slabs Figures 3.2.4(e) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 55
  56. 56. • Section 3.2.4 Precast Floors/Roof • Section 3.2.4.4 – Slab reinforcement cover • Table 3.2.4(a) – Unrestrained prestressed slabs • Table 3.2.4(b) – Unrestrained nonprestressed slabs • Figure 3.2.4(f) – Equivalent cover - IM, VCM or SMF SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 56
  57. 57. • Section 3.2.4 Precast Floors/Roof • Section 3.2.4.4 – Slab reinforcement cover SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 57
  58. 58. • Section 3.2.4 Precast Floors/Roof • Section 3.2.4.4 – Slab reinforcement cover SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 PRESCRIPTIVE 58
  59. 59. • Section 3.3 Rational Design • Precast Floor/Roof Slabs • Precast Beams SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 59
  60. 60. • Section 3.3 Rational Design • Conditions Covered • Simple and Continuous spans • Restrained and Unrestrained systems SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 60
  61. 61. • Section 3.3 Rational Design • 3.3. – Heat Transmission Criteria The minimum dimensions of a member are per Section 3.2.2 Heated Surface SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 61
  62. 62. • Section 3.3 Rational Design • 3.3.1 -Material properties at elevated temperature (Concrete) If concrete temperature > 9000F, reduced concrete compressive strength, f‘co, shall be used in calculating equivalent rectangular stress block, ao. Heated Surface SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 62
  63. 63. • Section 3.3 Rational Design • 3.3.1 -Material properties at elevated temperature (Steel) Steel temp is measured at centroid of reinforcement SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 63
  64. 64. • Section 3.3 Rational Design • 3.3.2 – Structural Capacity of unrestrained beams and slabs The applied moment, M, shall not exceed nominal flexural strength , Mno, at elevated temperature based on the internal temperature of steel and concrete. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 64
  65. 65. • Section 3.3 Rational Design • 3.3.2 – Demand for simply supported unrestrained slabs and beams M is determined from: 𝑀 1.0𝑀 1.0𝑀 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 65
  66. 66. • Section 3.3 Rational Design • 3.3.2 – Unrestrained simply supported slabs and beams Mno is determined from: Eq. 3.3.2‐1 Eq. 3.3.2‐2 Eq. 3.3.2‐3 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 66
  67. 67. • Section 3.3 Rational Design • 3.3.3 – Restrained simply supported slabs and beams For restrained systems the temperature of steel and concrete is determined at 1/2 of the fire resistance but not less than 1-hour. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 67
  68. 68. • Section 3.3 Rational Design • 3.3.4 – Beams and slabs continuous at supports The applied moment, M, shall not exceed nominal flexural strength , Mno, at elevated temperature based on the internal temperature of steel or concrete at the given fire resistance. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 68
  69. 69. • Section 3.3 Rational Design • 3.3.4.1 – Positive Moment • 3.3.4.2 – Negative Moment • The positive nominal flexural strength at elevated temperature, M+ no,, per Eq. 3.3.2-1. • The negative nominal flexural strength at elevated temperature, M- no,, per Eq. 3.3.2-1. • Applied negative moment, M-- shall not exceed M- no at elevated temp. Eq. 3.3.2‐1 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 69
  70. 70. • Section 3.3 Rational Design • 3.3.4.3 – Applied negative moment, M- • 3.3.4.3 (a) – Uniformly loaded member, continuous at one support using Fig. 3.3(a) and Eq 3.3.4-1 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 70
  71. 71. • Section 3.3 Rational Design • 3.3.4.3 – Applied negative moment, M- • 3.3.4.3 (a) – Uniformly loaded member, continuous at one support using Fig. 3.3(a) and Eq. 3.3.4-1 thru 3.3.4-3. Eq. 3.3.4‐1 Eq. 3.3.4‐2 Eq. 3.3.4‐3 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 71
  72. 72. • Section 3.3 Rational Design • 3.3.4.3 – Applied negative moment, M- • 3.3.4.3 (b) – Uniformly loaded member, continuous at two supports using Fig. 3.3(b) and Eq 3.3.4-4 thru 3.3.4-6 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 72
  73. 73. • Section 3.3 Rational Design • 3.3.4.3 – Applied negative moment, M- • 3.3.4.3 (b) – Uniformly loaded member, continuous at two supports using Fig. 3.3(b) and Eq 3.3.4-4 thru 3.3.4-6 Eq. 3.3.4‐4 Eq. 3.3.4‐5 Eq. 3.3.4‐6 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 73
  74. 74. • Section 3.3 Rational Design • 3.3.4.3 – Applied negative moment, M- • 3.3.4.3 (c) – Other cases not covered by 3.3.4 (a) or (b) The applied negative moment, M- , at the end of the member shall distribute loads based on reasonable assumptions for member stiffness and design fire conditions. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 74
  75. 75. • Section 3.3 Rational Design • 3.3.4.4 – Negative moment reinforcement • Consider effects on moment redistribution to prevent secondary failure • > 20% of maximum M- extend through span length • Negative moment reinforcement extend a development length beyond the inflection point, Xo , calculated using 1/2 of the required live load SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 75
  76. 76. • Section 3.3 Rational Design • 3.3.4.5 –Moment intensity, M/ Mn • Figures 3.3(c), 3.3(d) or 3.3(e) can be used to determine fire resistance of wide beams and slabs based on M/ Mn for carbonate, siliceous or sand-lightweight aggregate. • Figures not applicable if strands bundled SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 76
  77. 77. • Section 3.3 Rational Design • 3.3.4.5 – Moment intensity, M/ Mn • Figure 3.3(c) – carbonate aggregate SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 77
  78. 78. • Section 3.3 Rational Design • 3.3.5 – Moment intensity, M/ Mn • Beam widths > 10-inches and uniformly spaced strands in horizontal rows – fire resistance shall be based on effective distance u. Effective u = the average thickness of concrete between the centroid of the multiple strands and the nearest fire exposed surface. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 78
  79. 79. Example: Given: The 12RB24 shown Span = 30 ft Dead load (including beam weight) = 1.2 kip/ft Live load = 1.3 kip/ft Consider the component restrained for structural fire resistance determination. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 79
  80. 80. Example, continued: Siliceous aggregate concrete, f’c = 5000 psi, normalweight. Low-relaxation, ½-in.-diameter strand, fpu = 270 ksi Eight strands are shown provide a satisfactory design without fire considerations. Determine the necessary reinforcement for a 4-hr structural fire resistance rating. The beam is subjected to fire from below. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 80
  81. 81. Example, continued: Because the component is considered restrained, use rational design procedures for unrestrained component at one half the rating: that is, 2 hr. Note that IBC results may be more favorable. Try eight strands as shown: 𝐴 8 0.153 1.224 𝑖𝑛. 𝑦 5 2 3 4 8 2.75 𝑖𝑛. 𝑑 24 2.75 21.25 𝑖𝑛. 𝑢 3 2 2 2 0.5 2 2 1 4 8 2.0 𝑖𝑛. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 81
  82. 82. Example, continued: From PCI 124-18 Figure 2.2(c), siliceous aggregate, at 2-hr, strand temperature = 750°F. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 82
  83. 83. Example, continued: From PCI 124-18 Figure 2.2(a) Percentage of strength at 750°F = 54% SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 83
  84. 84. Example, continued: 𝑓 0.54 270 145.8 𝑘𝑠𝑖 From IHB 8th ed. Eq. 5‐1 with 𝛾 0.28, 𝛽 0.8, 𝜌 , 𝑓 𝑓 , 𝑑 21.25 𝑖𝑛. 𝑓 1 𝛾 𝐴 𝑓 𝛽 𝑏𝑑𝑓′ 1 0.28 1.224 145.8 0.8 12 21.25 5 138.7 𝑘𝑠𝑖 𝑎 𝐴 𝑓 0.85𝑓′ 𝑏 1.224 135.6 0.85 5 12 3.33 𝑖𝑛. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 84
  85. 85. Example, continued: 𝑀 𝐴 𝑓 𝑑 𝑎 2 1.224 138.7 21.25 3.33 2 3325 𝑘𝑖𝑝-𝑖𝑛. 277 𝑘𝑖𝑝-𝑓𝑡 Service load moment (conservatively check condition as a simple span): 𝑤 1.20 1.30 2.50 𝑘𝑖𝑝/𝑓𝑡 𝑀 𝑤ℓ 8 2.50 30 8 𝑀 281 𝑘𝑖𝑝-𝑓𝑡 277 𝑘𝑖𝑝-𝑓𝑡 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 85
  86. 86. Example, continued: Therefore, the beam will not satisfy criteria for a 4‐hr fire endurance. Try adding two no. 4 bars, 𝑓 60 𝑘𝑠𝑖, at 6 in. from bottom as shown: 𝐴 0.40 𝑖𝑛. ; 𝑓 60 𝑘𝑠𝑖 𝑑 𝑏𝑎𝑟𝑠 24 6 18 𝑖𝑛. 𝑢 𝑏𝑎𝑟𝑠 2 𝑖𝑛. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 86
  87. 87. Example, continued: From PCI 124‐18 Figure 2.2(c), bar temperature at 2‐hr = 750°F From PCI 124‐18 Figure 2.2(a), (hot‐rolled steel): %𝑓 77%, 𝑓 0.77 60 46.2 𝑘𝑠𝑖 Reevaluate 𝑓 considering the effect of bars: 𝜌 , 𝜌 From Eq. 5‐1: 𝑓 𝑓 1 𝛾 𝛽 𝜌 𝑓 𝑓′ 𝑑 𝑑 𝑓 𝑓 𝜌 𝜌 𝑓 145.8 1 . . . . . . . . 0 137.9 𝑘𝑠𝑖 SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 87
  88. 88. Example, cont’d: 𝑓 145.8 1 . . . . . . . . 0 137.9 𝑘𝑠𝑖 𝑎 1.224 137.9 0.40 46.2 0.85 5 12 3.67 𝑖𝑛. 𝑀 𝑠𝑡𝑟𝑎𝑛𝑑 1.224 137.9 21.25 3.67 2 3277 𝑘𝑖𝑝-𝑖𝑛. 273 𝑘𝑖𝑝-𝑓𝑡 𝑀 𝑏𝑎𝑟𝑠 0.4 46.2 18 . 299 𝑘𝑖𝑝-𝑖𝑛. 25 𝑘𝑖𝑝-𝑓𝑡 𝑀 𝑡𝑜𝑡𝑎𝑙 273 25 298 𝑘𝑖𝑝-𝑓𝑡 281 𝑘𝑖𝑝-𝑓𝑡 Cross section is 4‐hr fire rated. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 RATIONAL DESIGN 88
  89. 89. • Chapter 4 Special Considerations • Section 4.2 Opening protection • 4.2.1 Poke-through devices • 4.2.2 Joints in precast elements • Section 4.3 Connection protection Joints Poke‐through Steel brackets SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 89
  90. 90. • Section 4.2.1 - Poke-through devices • Sprayed mineral fiber – Fig. 4.2(a) • Vermiculite cementitious – Fig. 4.2(b) • Perlite concrete shield – Fig. 4.2(c) • Mineral insulation board – Fig. 4.2(d) • Mineral wool insulation – Fig. 4.2(e) Protection thickness applied to underside of slab SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 90
  91. 91. • Section 4.2.1 - Poke-through devices • Sprayed mineral fiber – Fig. 4.2(a) Protection thickness applied to underside of slab 2-hour slab. Thickness – 1.3 in. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 91
  92. 92. • Section 4.2.2 - Joints • 4.2.2.1 – Wall joints • No requirement where building codes allows unprotected openings • Protected joints based on joint type, joint materials, joint width, wall panel thickness, and required fire resistance. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 92
  93. 93. • Section 4.2.2 - Joints • 4.2.2.1 – Wall joints • Two-stage cavity joint – Fig. 4.2(f) • Two-stage shiplap joint – Fig. 4.2(g) • Sealant & backer rod joint – Fig. 4.2(h) • Ceramic blanket for joints – Fig. 4.2(i) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 93
  94. 94. • Section 4.2.2 - Joints • Fig. 4.2 (h) – Sealant/backer rod joints 1-hour wall . SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 94
  95. 95. • Section 4.2.2 - Joints • 4.2.2.2 – Slab joints • Unprotected when permitted by building code • 1-in minimum concrete topping • Grout to minimum 1-inch depth but not less than 1/3 slab thickness SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 95
  96. 96. • Section 4.3 – Connection protection • 4.3.1 – Steel brackets – exposed • Figure 4.3(a) • Sprayed mineral fiber (SMF) • Vermiculite cementitious material (VCM) • Intumescent mastics (IM) SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 96
  97. 97. • Section 4.3 – Connection protection • 4.3.1 – Steel brackets - exposed • 2-hour fire resistance • Steel bracket thickness, t = 5/16 in. • SMF or VCM @ 1-1/2 in. • Steel bracket thickness, t = 1-1/16 in. • SMF or VCM @ 3/4-in. Fire resistance, hr SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 97
  98. 98. • Section 4.3 – Connection protection • 4.3.2 Ledges, pockets and corbels – none if integral with precast element and designed for required fire resistance. SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 SPECIAL CONSIDERATIONS 98
  99. 99. • Appendix - Commentary • Section C2.2 – Steel properties • Section C2.3 – Concrete properties SPECIFICATION FOR FIRE RESISTANCE OF PRECAST/PRESTRESSED CONCRETE PCI 124 APPENDIX 99
  100. 100. QUESTIONS?
  101. 101. 01. TITLE OF PRESENTATION THANK YOU

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