The culvert is treated as a rigid frame. The following manual steps are standard: Box Culvert Design Example - MnDOT
The following design calculations are typically performed when designing a box culvert: box culvert design calculations pdf
where Q was the flow rate, n was the Manning's roughness coefficient, A was the cross-sectional area, R was the hydraulic radius, and S was the slope. The culvert is treated as a rigid frame
The structure is modeled with nodes at the corners (joints). The stiffness of the members ($EI/L$) determines the distribution of moments. The stiffness of the members ($EI/L$) determines the
| Combination | Factors | Intended Use | |-------------|---------|---------------| | Strength I | 1.25 DL + 1.75 LL | Basic design | | Strength III | 1.25 DL + 1.35 (wind/water) | Extreme events | | Service I | 1.00 DL + 1.00 LL | Crack control & deflection | | Extreme Event II | 1.00 DL + 1.00 (flood/ice) | |
: Design span (distance between sidewall centerlines) and clear height. 2. Load Calculations A box culvert must resist four primary types of loads: