Distribute the weight of one railing to no more than three girders, applied to the composite cross section.

Use section properties given on the Prestressed Concrete I-Girders Details (IGD) standard drawings. For the composite section, use gross section properties.

Composite section properties may be calculated assuming the girder and slab to have the same modulus of elasticity (for girders with $f_c^{\text{'}}$
< 8.5 ksi). Do not include haunch concrete placed on top of the girder when determining section properties. Section properties based on final girder and slab modulus of elasticity may also be used; however, this design assumption must be noted on the plans.

Live load distribution factors must conform to Article 4.6.2.2.2 for flexural moment and Article 4.6.2.2.3 for shear, except as noted below:

For exterior girder design with a slab cantilever length equal to or less than onehalf of the adjacent interior girder spacing, treat the exterior girder as if it were an interior girder to determine the live load distribution factor for the interior girder. The slab cantilever length is defined as the distance from the centerline of the exterior girder to the edge of the slab.
For exterior girder design with a slab cantilever length exceeding one-half of the adjacent interior girder spacing, use the lever rule with the multiple presence factor of 1.0 for single lane to determine the live load distribution.

The live load used to design the exterior beam must never be less than the live load used to design an interior beam of comparable length.

Do not use the special analysis based on conventional approximation for loads on piles per Article C4.6.2.2.2d, unless the effectiveness of diaphragms on the lateral distribution of truck loads is investigated.

Do not take the live load distribution factor for moment or shear as less than the number of lanes divided by the number of girders, including the multiple presence factor per Article 3.6.1.1.2.

When prestressed concrete deck panels or stay-in-place metal forms are allowed, design the beam using the basic slab thickness.