Deflection Check - Culvert
Deflection Check - Culvert
(OP)
Hi Everyone,
I finished designing a three sided culvert and wanted to know if anyone had an approach, method, or guide for checking the deflection.
I want to make sure the peak is adequate for no ponding on the structure.
Thanks!
I finished designing a three sided culvert and wanted to know if anyone had an approach, method, or guide for checking the deflection.
I want to make sure the peak is adequate for no ponding on the structure.
Thanks!






RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
Once you have this, I used a software package to design the culvert.
What state are you in?
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
You first estimate the deflection with a realistic modulus of deformation of the concrete at 28 days, and separate the deflections corresponding to
DL Dead Loads
SDL Superimposed Dead Loads
LL Live Loads
All these would be then ordinary elastic deflections, only separated by cause (what can be made dedicating separate hypotheses).
Then, the total final deflection will be in the range of...
DeltaDL·2.8+DeltaSDL·1.9+DeltaLL·1
This should be lesser than span/250.
The Active deflection, which is the one able to cause damage in nonattached parts will be in the range of...
DeltaDL·0.9+DeltaSDL·0.9+DeltaLL·1
In buildings, shouldn't be more than span/400 nor 1 cm
This is a quick way to estimate relevant parameters of RC deflection on the otherwise always quite inaccurate subject of RC deflections.
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
I guess I could talk to the precasters and see if they can add a small crown or peak to the culvert?
RE: Deflection Check - Culvert
RE: Deflection Check - Culvert
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RE: Deflection Check - Culvert
Also, even if lesser LL than 100%LL could lead to more realistic evaluation of the actual deflection (and especially of the active one, able to cause actual damage), a normative check would involve 100%LL
An initial analysis with gross inertia may soon reveal the extent of the cracked zones then leading to adjudication of new stiffnesses in the model.
I have even coarser rules of thumb for RC deflection checks; one that has proven generally satisfactory for actual ordinary building structures in two senses
1. that no notorious problems appear in the building caused by deflection
2. that if you check in more detailed way the deflection you use to get satisfactory compliance of the code
is using gross sections' inertiae and modulus of deformation as directly by default given by RISA 3D (or if you want, Ec at 28 days age from ACI or EHE code) and limit the maximum service level deflection to 7 mm. I have been pushed sometimes by the undersigning architects to twice that limit rule of thumb deflection check in spans just a bit over 9 m and still be able to show code compliance.
AND ... remember this is only a guide on deflection for ordinary buildings, say houses, condominiums, offices, maybe some retail buildings, not THE proper check.