[ K = \fracM_Edb d^2 f_cd = \frac45 \times 10^61000 \times 204^2 \times 20 = 0.054 ] [ z = d \left(0.5 + \sqrt0.25 - \fracK1.134\right) \leq 0.95d ] Here K < 0.167 → compression reinforcement not required. z ≈ 0.96d → use 0.95d = 194 mm.
A box culvert is a rigid frame structure typically used to convey water (drainage, streams) or as a pedestrian/equestrian underpass. In the context of Eurocode 2, a box culvert is analyzed as a closed frame. The design must satisfy Ultimate Limit State (ULS) for strength and Serviceability Limit State (SLS) for crack width and deflection control. box culvert design calculations eurocode 2021