What is the maximum ground slope under stacked shipping containers to prevent tipping?

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atef81 (Structural)

(OP)

3 Apr 23 06:15

Hi, what would be the maximum allowable ground slope (longitudinally and transversally) under stacked shipping containers?

I am trying to design rigid pavement (concrete) under stacked full containers and trying to find out the maximum acceptable slope before containers tip over.
I looked in 3711.10-2000_R2016 and some technical papers, but can't find an answer.
I got a verbal advice saying 1%, but don't know where this value comes from.

Thanks in advance.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

LittleInch (Petroleum)3 Apr 23 06:34

Max number of containers?

Empty or full? Or a mixture?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

3DDave (Aerospace)3 Apr 23 06:58

Not only slope, but also wind can topple them. You can control the slope - so 1% is a worthwhile limit.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

LittleWheels (Structural)3 Apr 23 09:22

1.0% cross-fall for container stacking is the common design standard in the industry. Some container handling equipment (particularly automated) can't cope with much more cross-fall than that. The Britpave Concrete Hardstanding Design Manual recommends not exceeding 1:60 but I design at 1.0%. Depending on pavement type, it can be difficult to reliably achieve flatter than that without ponding (ice becomes a problem in some localities) when construction tolerances and settlement is considered.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

LittleInch (Petroleum)3 Apr 23 09:50

A 1% cross fall is max 25mm / 1 inch edge to edge.

Lengthways it is 150mm / 6 inches - that sounds too much to me so there might be different numbers for cross fall and lengthways

But this is not a realistic calculation unless you are expecting containers stacked 10 high or more? Most advice seem to be no more than 9 high and maybe less depending on the max weight.

Why are you doing this?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

LittleWheels (Structural)3 Apr 23 10:37

Containers are generally 7-high max for 40' loaded and sometimes up to 9-high for 20' loaded. Empties can go higher but are more likely to be toppled in high wind. Most containers are 40', so most container handling equipment tops out at 7-high stacks (or lower).

Most container pavement design approaches include reduction factors for loaded container stacks as it is uncommon for all containers in a stack to be fully loaded.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

bimr (Civil/Environmental)3 Apr 23 14:36

Most of the empty container storage yards at the firm I worked for have 6-Inch concrete pavement and limit the height to 5 containers. The containers are also arranged to provide resistance to being blown over by the wind.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

dik (Structural)6 Apr 23 15:14

1% is the bare minimum for drainage, too.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

BridgeSmith (Structural)6 Apr 23 19:22

It depends on several factors - the height of the center of gravity, the bearing capacity and settlement characteristics of the material supporting the containers. the more eccentricity there is, the higher the pressure at the edge of the container, which leads to the edge sinking further into the substrate, which leads to greater eccentricity, which leads to more settlement. Probably not significant for a stack of 2 or 3 containers, but it definitely matters if the stack is 5, 6 or more.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

MotorCity (Structural)6 Apr 23 20:09

To summarize the suggestions above, you need to draw a free body diagram, apply the loads, and perform an analysis. There may be guidelines or rules of thumb but there are too many variables to provide you with a definite answer.

Just food for thought.....1% was mentioned in several responses above. It seems like the containers could tolerate a slope significantly larger than this given the potential for rough seas as the container ship they are stacked on tilts/rocks back and forth.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

LittleInch (Petroleum)6 Apr 23 22:04

The stacks on the ship though get locked together and cross braced which is quite different to a surface stack.

And sometimes they fall off the ship....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: What is the maximum ground slope under stacked shipping containers to prevent tipping?

dik (Structural)6 Apr 23 22:30

only the weak and injured ones...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

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