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Lecture 24 - Design of Two-Way Floor Slab System

Lecture Goals. Shear Strength of SlabsShear ExampleDirect Design Method . Shear Strength of Slabs . In two-way floor systems, the slab must have adequate thickness to resist both bending moments and shear forces at critical section. There are three cases to look at for shear.. Two-way Slabs supported on beamsTwo-Way Slabs without beamsShear Reinforcement in two-way slabs without beams..

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Lecture 24 - Design of Two-Way Floor Slab System

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    1. Lecture 24 - Design of Two-Way Floor Slab System August 4, 2003 CVEN 444

    2. Lecture Goals Shear Strength of Slabs Shear Example Direct Design Method

    3. Shear Strength of Slabs

    4. Shear Strength of Slabs

    5. Shear Strength of Slabs

    6. Shear Strength of Slabs

    7. Shear Strength of Slabs

    8. Shear Strength of Slabs

    9. Shear Strength of Slabs

    10. Shear Strength of Slabs

    11. Shear Strength of Slabs

    12. Shear Strength of Slabs

    13. Shear Strength of Slabs

    14. Shear Strength of Slabs

    15. Shear Strength of Slabs

    16. Shear Strength of Slabs

    17. Shear Strength of Slabs

    18. Example Problem

    19. Example Problem

    20. Example Problem

    21. Example Problem

    22. Example Problem

    23. Example Problem

    24. Example Problem

    25. Example Problem

    26. Example Problem

    27. Example Problem

    28. Example Problem

    29. Direct Design Method for Two-way Slab Minimum of 3 continuous spans in each direction. (3 x 3 panel) Rectangular panels with long span/short span 2

    30. Direct Design Method for Two-way Slab

    31. Direct Design Method for Two-way Slab

    32. Direct Design Method for Two-way Slab For panels with beams between supports on all sides, relative stiffness of the beams in the 2 perpendicular directions. Shall not be less than 0.2 nor greater than 5.0

    33. Definition of Beam-to-Slab Stiffness Ratio, a

    34. Definition of Beam-to-Slab Stiffness Ratio, a

    35. Two-Way Slab Design

    36. Two-Way Slab Design

    37. Two-Way Slab Design

    38. Basic Steps in Two-way Slab Design Choose layout and type of slab. Choose slab thickness to control deflection. Also, check if thickness is adequate for shear. Choose Design method Equivalent Frame Method- use elastic frame analysis to compute positive and negative moments Direct Design Method - uses coefficients to compute positive and negative slab moments

    39. Basic Steps in Two-way Slab Design Calculate positive and negative moments in the slab. Determine distribution of moments across the width of the slab. - Based on geometry and beam stiffness. Assign a portion of moment to beams, if present. Design reinforcement for moments from steps 5 and 6. Check shear strengths at the columns

    40. Minimum Slab Thickness for two-way construction

    41. Distribution of Moments

    42. Distribution of Moments

    43. Distribution of Moments

    44. Column Strips and Middle Strips

    45. Column Strips and Middle Strips

    46. Column Strips and Middle Strips

    47. Positive and Negative Moments in Panels

    48. Moment Distribution

    49. Positive and Negative Moments in Panels

    50. Longitudinal Distribution of Moments in Slabs

    51. Distribution of M0

    52. Moment Distribution

    53. Transverse Distribution of Moments

    54. Transverse Distribution of Moments

    55. Transverse Distribution of Moments

    56. Distribution of M0

    57. Factored Moment in Column Strip

    58. Factored Moment in an Interior Strip

    59. Factored Moment in an Exterior Panel

    60. Factored Moment in an Exterior Panel

    61. Factored Moment in Column Strip

    62. Factored Moment in Column Strip

    63. Factored Moment in Column Strip

    64. Factored Moments

    65. Factored Moments

    66. ACI Provisions for Effects of Pattern Loads

    67. ACI Provisions for Effects of Pattern Loads

    68. Reinforcement Details Loads

    69. Reinforcement Details Loads

    70. Minimum extension for reinforcement in slabs without beams(Fig. 13.3.8)

    71. Moment Distribution

    72. Transverse Distribution of Moments

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