Distribution of Loads
Dead Loads
As shown in the following figure, the different loads are distributed based on either the tributary width or tributary width fraction. For an interior beam, the tributary width is calculated as half of the spacing to the CL of the beams on each side of the beam under consideration. For an exterior beam, the tributary width extends from the edge of the bridge to half the spacing to the next beam.
Dead Load Due to Deck Self-Weight
The procedure to compute the uniform dead load on precast due to self-weight of deck is as follows:
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The thickness of topping is multiplied by the tributary width of the girder and the concrete unit weight to obtain the uniform dead load in kip/ft (kN/m) acting on the girder. The weight of the haunch is then added or subtracted from this load.
- A simple span beam analysis is performed to compute moments and shears at tenth points on the girder.