Regarding Bulging limit for rectangular steel tank- rest on gound

[Arbu]

Dear All,

I am trying to analyse one Rectangular steel tank (water) having size approx. L X W X H = 8 x 1.5 x 2.2 m. I modelled it in STAAD Pro and applied loads as below:
1. Side walls hydrostatic pressure triangular
2. Base uniform pressure with intensity H x water density.

The tank will be fabricated by MS Plate 3 mm thick and reinforced by MS channels out side. Also inside wall is having a FRP sheet covering of 5 mm.
The tank will be resting on concrete. When I am analysing for the above loads I am getting a lateral deflection of top channel (Bulging) around 70 mm.

My doubt are
1. There is any standard for limiting the bulging (lateral deflection) of the rectangular top open Tank.
2. I modelled the MS plate with channels and I ignored FRP sheet, is this approach is correct?. Do I need to model FRP sheet also?

Please guide.

regards,
Arbu

 

[Arbu]

Dear All,

I modified the design as per my understanding and the forces in member.

Original design by supplier:

After analysing the tank I found that the long side is not having much effect of hoop tension as tank is long , therefore for central portion I considered as you frames and increased the channel size from 75x40 to 100x50 . and strengthen the top ring beam as its holding all together and will reduce the bulging.

But only one thing need modification that the bottom of the channel should be flush on bottom side so resting of tank will not be a problem. Also now Bulging is 19 mm only.

Please suggest.