|
|
||
|
|
|
|
From the same paper as the previous two slides.
Note the develpment of “Elephant’s Foot” buckles, both at the bottom of the tank where the loads are highest but where the tank is thickest, and about halfway up the tank wall where the loads are less but where the tank wall is thinner.
There is a photograph in the “Unstiffened Cylindrical Shell” slide show that shows “Elephant’s Foot” buckling about half way up the wall of a liquid storage tank that failed during an earthquake. (In that picture there also appears an “Elephant’s Foot” buckle at the bottom of that tank, a buckle that is mostly obscured by bushes in the foreground.) Part of the discussion associated with that other photograph reads: “The highest axial compressive resultant (compressive force per circumferential arc length) occurs at the bottom of the tank. However, the tank is built up of courses that are thickest at the bottom and become thinner in steps with increasing distance from the bottom. The "elephant foot” buckle about half way up the tank occurs at a level where the tank wall thickness steps down from one course to the next higher course.”
Page 81 / 216