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Section 9.4.1 RC Slab Crack Control

User defined reinforcement that is at an angle to the cross section will only have the component perpendicular to the cross section considered.

Section (a) –This section is not implemented here. Clause 9.1.1 is implemented in the minimum reinforcement design via clause 8.1.6.1.

Section (b) – This section is always used in the service design, but never used in the max service design.

  • Reinforcement is added to limit maximum spacing to 300 mm or two times the cross section depth. All bars on the appropriate face (including fractional components for bars at an angle to the cross section) are considered for spacing requirements. A fraction number of bars and number of spaces may be used.
  • Bars with a diameter of less than half the diameter of the maximum bar diameter on the face being considered are converted to an equivalent number of hypothetical bars with a diameter of half the maximum bar diameter. This conversion is based upon area.

Section (c) – This section is only used for service design, but is not used in protected environments.

  • Reinforcement is added both faces to keep the reinforcement stresses within the limits of Table 9.4.1(A) or Table 9.4.1(B), whichever is larger.
  • The maximum diameter of all reinforcement assigned to a particular face is used in Table 9.4.1(A).
  • The bar spacing for Table 9.4.1(B) is calculated using all bars on the appropriate face (including fractional components for bars at an angle to the cross section). Bars with a diameter of less than half the diameter of the maximum bar diameter on the face being considered are converted to an equivalent number of hypothetical bars with a diameter of half the maximum bar diameter. This conversion is based upon area. A fractional number of bars and number of spaces may be used.

Section (d) – This section is only used for max service design, but is not used in protected environments.

  • Reinforcement is added to both faces to keep the reinforcement stresses less than 0.8 fsy.