JSanchez88
Structural
- Apr 6, 2012
- 14
Hello,
I have been asked to design a new CIP box culvert that is to replace an existing culvert. The new culvert is 13'(W) x 15'(H) clear inside dimensions. I have already looked at several DOT (TX, KS, and MN) guides along with ASTM C857-12a and applied loads to it accordingly:
1. Vertical Earth Load on the roof
2. 3 and 4 axle HS20-44 Loads traveling across the culvert (applied in separate conditions)
3. (2) trucks side by side traveling parallel to the culvert
4. Lateral earth pressure when the water level is both above and below the culvert
5. Corresponding hydrostatic pressure when water level is above the culvert
6. Surcharge of the wheel loads
7. Interior hydrostatic pressure when the culvert is full
When figuring the slab and wall thicknesses without shear reinforcing, they become excessively large (21" - 28"). When looking at the plans for the existing culvert(which is dated around 1960), their design calls for 12" thicknesses. I've also seen several box culverts being designed to have wall thicknesses between 12-18" and slabs up to 24" - but not up to 28!
I know recent designs are made to where the thicknesses are just large enough to not require any type of shear reinforcing but are not needing to be 21-28".
My question is: Am I taking something into account that I shouldn't? If not, are there any recommendations to yield a more suitable design thickness?
I have been asked to design a new CIP box culvert that is to replace an existing culvert. The new culvert is 13'(W) x 15'(H) clear inside dimensions. I have already looked at several DOT (TX, KS, and MN) guides along with ASTM C857-12a and applied loads to it accordingly:
1. Vertical Earth Load on the roof
2. 3 and 4 axle HS20-44 Loads traveling across the culvert (applied in separate conditions)
3. (2) trucks side by side traveling parallel to the culvert
4. Lateral earth pressure when the water level is both above and below the culvert
5. Corresponding hydrostatic pressure when water level is above the culvert
6. Surcharge of the wheel loads
7. Interior hydrostatic pressure when the culvert is full
When figuring the slab and wall thicknesses without shear reinforcing, they become excessively large (21" - 28"). When looking at the plans for the existing culvert(which is dated around 1960), their design calls for 12" thicknesses. I've also seen several box culverts being designed to have wall thicknesses between 12-18" and slabs up to 24" - but not up to 28!
I know recent designs are made to where the thicknesses are just large enough to not require any type of shear reinforcing but are not needing to be 21-28".
My question is: Am I taking something into account that I shouldn't? If not, are there any recommendations to yield a more suitable design thickness?
