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Corrugated rectangular tank

Corrugated rectangular tank

(OP)
Dear All,

Can you edify me on design of corrugated rectangular tank. Earlier i have designed rectangular tank as per Roark's formulae.

But this time, it is corrugated tank : so per my understanding it would be difficult to add stiffeners on wall.

Thus, without stiffeners bending stresses generated in the wall would be high & it would ultimately result into higher thickness.

So can we take advantage of corrugation provided on wall of tanks to lower bending stress.
If yes then how ?
OR
what is alternative for it
Also what is purpose of corrugation.

Tank dimensions (Just for information)
L=6000mm
W=1500mm
H=1700mm.

Thanks in advance for your guidance.

RE: Corrugated rectangular tank

(OP)
In my understanding, moment of inertia of provided corrugation need to calculated and same shall be compared with required moment of inertia.
Or
corrugation dimensions shall be finalized on the basis of required moment of inertia.

Kindly suggest.

RE: Corrugated rectangular tank

I would say run the corrugation lengthwise (horizontally) for the walls of the tank. The corrugation will be your stiffeners. The corrugation of the tank bottom would align with the longest span between the walls. In my opinion the deflection equation of the walls and bottom will govern over the stress equations.

RE: Corrugated rectangular tank

If the corrugations do not provide adequate stiffness by themselves, then you will have to add stiffener ribs. In that case the stiffener ribs would be horizontal and the corrugations would be vertical.

RE: Corrugated rectangular tank

Corrugation on the walls should be aligned vertically. See the bottom of page 132ff of this document for some guidance.

I used to count sand. Now I don't count at all.

RE: Corrugated rectangular tank

SandCounter, you have shown an article about sheet piles. In this case, the corrugation is aligned vertically and one of the primary reason is that they are driven either with hydraulic vibratory, diesel or air operated drop hammers which will make the piles bend when there is resistance from the ground. Your article is good but for an entirely different application.

RE: Corrugated rectangular tank

Chicopee, sheet piles? No, I don't think so, take a closer look. This is steel vessel rules (SVR) from the American Bureau of Shipping.

I used to count sand. Now I don't count at all.

RE: Corrugated rectangular tank

My mistake about sheet piles, similar shapes but no interlock as they are corrugated bulkhead per design on pg 123 and 124; nonetheless they are still to be driven by some sort of a hammer and they will bend when encountering resistance, so obviously the corrugation will be aligned vertically. By contrast, we have on occasion used guard rails as temporary retaining walls and the corrugation was aligned horizontally, not vertically.

RE: Corrugated rectangular tank

Actually the corrugations should align with the shortest span.

RE: Corrugated rectangular tank

Uh, how do you seal the corrugations at the corners and/or bottom?
Seems nontrivial to me.


Mike Halloran
Pembroke Pines, FL, USA

RE: Corrugated rectangular tank

The corrugated bulkheads shown in Soundcounter's link get welded; The dock corrugated bulkheads have interlocks allowing one sheet to slide into another when hammered.

RE: Corrugated rectangular tank

(OP)
Thank you all for your guidance.

Below is my understanding for checking / deciding corrugation dimensions:

In absence of stiffeners, unstiffened length would be same as length of tank (if corrugation is run along the length).

Considering unstiffened length (tank length), bending moment would be calculated and thus this would result into requirement of high moment of inertia.

In order to satisfy above requirement, required moment of inertia < no of corrugation X Moment of inertia of single corrugation.

This is how quantity and dimensions of corrugation (trapezoidal) is to be decided.

Is my understanding correct?

If wrong than please correct me.

RE: Corrugated rectangular tank

The other way to figure out corrugation dimensions is to find out what size you have tools to make.

;---

Separately, note that corrugations add some complexity to the stress conditions at intersections, which complicates the fatigue analysis.

Mike Halloran
Pembroke Pines, FL, USA

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