Axial pipe load - how is this transferred to the pad foundation

[Anaheim]

I have a query that I need some advice on. I am checking the bearing capacity of pad foundations supporting an above-ground pipeline. The pipeline team have provided loads, which include an axial load along the longitudinal axis of the pipe, a lateral load and a vertical load. The civil engineer advised me to apply an overturning moment caused by the axial load (lever arm of 1m) which causes a very large load eccentricity significantly reducing the effective breadth of the foundation. The pad foundations are typically quite small (1m x 1m x 0.5m deep) and therefore I am sceptical that the axial load would induce such a large moment. The lateral loads in the direction perpendicular to the pipeline are relatively small and are not an issue in terms of eccentric loading. Instead, would the axial load not transfer a frictional load to the foundation?

Any advice would be greatly appreciated.

 

[1503-44]

They're about as close to no load, no restraint as you can get. Always used on refinery heat exchanger pedestals. Make the top pad larger than the bottom to keep out the dirt and sand and thereby reduce wear.

 

[Anaheim]

Thank you for your contributions and for sharing your extensive knowledge and experience on this topic. I've learnt a lot and obtained valuable tips.

 

[LittleInch]

Have you re designed your toppling over support though?

 

[Anaheim]

Have you re designed your toppling over support though?

For FEED design, I looked at the raw loads at each support provided by pipe stress and using statistics I was able to design my sleeper foundation. There are some supports for which the typical sleeper foundation would not work; those will be looked at during detailed design and a bespoke solution provided. There is talk of the pipe stress discipline doing another iteration in detailed design to introduce more flexibility into the system.