Code References
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Here, only the red part of the moment curve will be applied to the cracked section.
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Creep and Shrinkage Multipliers
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Condition | Factor | Equation # |
|---|---|---|
Erection: SW Deflection | 1.85 | 1 |
Erection: P/S Camber | 1.80 | 2 |
Final: SW Deflection (non-comp) | 2.70 | 3 |
Final: SD Deflection (non-comp) | 2.45 | 4 |
Final: SW Deflection (non-comp) | 3.00 | 5 |
Final: SW Deflection (comp) | 2.40 | 6 |
Final: P/S Camber (comp) | 2.20 | 7 |
Final: SD Deflection (comp) | 3.00 | 8 |
Final: Topping Deflection (comp) | 2.30 | 9 |
In graphical terms, these relationships can be shown as below:
For plant topped (non-composite) members:
For field topped (composite) members:
In ACI 318-71 9.5.2.3, the base factor used to modify initial deflections to account for long-term effects was calculated using the following equation:
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Mild deflection multipliers are calculated using Eq. 24.2.4.1.1 (shown below). For this method, each load combination computes its’ own reinforcement ratio. In addition, the time-dependent factor is set to 2 for final loading and all other stages.
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where λ is the deflection multiplier
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This deflection multiplier is applied to all sustained loads on the members.
Hand Calculation
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