Eriksson Culvert follows ACI 350 chapter 9 for strength and serviceability requirements. This states that the required strength for non-compression controlled sections shall be multiplied by S_d.
where f_s can be calculated as:
Exposure | One-way | Two-way |
|---|---|---|
Normal |  |  |
Severe |  |  |
The strain gradient amplification factor (beta) in these equations is calculated as:
It is permitted to use beta of 1.2 if h >= 16” and 1.35 if h < 16”.
It is also permitted to use 25 for the 4(2 + d_b/2)^2 term as a simplification.