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# 24.2.3 *Calculation of Immediate Deflections*

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Immediate deflections shall be calculated using methods or formulas for elastic deflections, considering effects of cracking and reinforcement on member stiffness.

Effect of variation of cross-sectional properties, such as haunches, shall be considered when calculating deflections.

Deflections in two-way slab systems shall be calculated taking into account size and shape of the panel, conditions of support, and nature of restraints at the panel edges.

For nonprestressed members, effective moment of inertia,

**, shall be calculated by Eq. (24.2.3.5a) unless obtained by a more comprehensive analysis, but***I*_{e}**shall not be greater than***I*_{e}**.***I*_{g}(24.2.3.5a) |

where ** M_{cr}** is calculated by

(24.2.3.5b) |

For prestressed Class T and Class C slabs and beams as defined in 24.5.2, deflection calculations shall be based on a cracked transformed section analysis. It shall be permitted to base deflection calculations on a bilinear moment-deflection relationship or

**in accordance with Eq. (24.2.3.5a), where***I*_{e}**is calculated as:***M*_{cr}(24.2.3.9) |

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24.2.3.7 Serviceability Requirements,

For prismatic one-way slabs and beams, I e shall be permitted to be taken as the value obtained from Eq. (24.2.3.5a) at midspan for simple ...

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