Bridges & Structures

Comprehensive Design Example for Prestressed Concrete (PSC) Girder Superstructure Bridge

3. Flow Charts

Live Load Distribution Factor Calculations Flow Chart Text

Return to Flow Chart

1. Determine the type of cross-section, Table S4.6.2.2.1-1  (Design Step 5.1)
2. Determine the Kg factor (S4.6.2.2.1)  (Design Step 5.1.3)
3. For skewed bridges, determine the skew correction factor for moment (if allowed by the owner) (S4.6.2.2.2e) and for shear (S4.6.2.2.3c)  (Design Step 5.1.6)
4. Determine LL distribution factors for moment for the interior girder under single lane and multi-lane loading (S4.6.2.2.2b)  (Design Step 5.1.5)
5. Determine LL distribution factor for shear for the interior girder under single lane and multi-lane loading (S4.6.2.2.3a)  (Design Step 5.1.7)
6. Apply the skew correction factor  (Design Step 5.1.8)
7. Determine the controlling (larger) distribution factors for moment and shear for the interior girder  (Design Step 5.1.9)
8. Divide the single lane distribution factors by the multiple presence factor for one lane loaded,1.2, to determine the fatigue distribution factors (Notice that fatigue is not an issue for conventional P/S girders.  This step is provided here to have a complete general reference for distribution factor calculations.)
9. Repeat the calculations for the exterior girder using S4.6.2.2.2d for moment and S4.6.2.2.3b for shear  (Design Step 5.1.10)
10. Additional check for the exterior girder for bridges with rigidly connected girders  (Design Step 5.1.15)

END.

Return to Flow Chart