Water Tank Design

Dear Engineers,

Im designing Square Steel water tank using STAAD. I have few doubt. pls.  clarify if u have could... Thanks in advance.

1) say the size is 3m x 3m x 2m 

Hence volume = 18m3

Weight of water =18*1000 = 18000kg

Pressure on bottom of the tank will be 2000kg/m2

How to calculate the pressure on side wall of the tank

2) When there are so many stress result is shown in post-processing . Which stress do we need to consider for design. Is max Absolute  ok?

  • Lateral pressure can be calculated by multiplying the Gamma ( density ) by the depth. You can use the Hydrostatic plate load option in STAAD.Pro and it would apply the pressure appropriately on the walls.

    Regarding your question on which stress to look at, it depends on what you are trying to do. Reinforcements can be designed based on the MX and MY moments. If you are looking for axial stress in the walls you will be looking at SX or SY. If you are looking for out of plane shear stresses you can check the SQX, SQY. Max Von Mises stress is a good measure of total stress as it combines axial, bending and in plane shear.  



  • hello sir,

    My doubt continues as...

    Regarding your question on which stress to look at, it depends on what you are trying to do. Reinforcements can be designed based on the MX and MY moments.
    1. at centre or edges of plate (as there is great difference)


    2. FY: 389.997 MPA FC: 25.000 MPA COVER (TOP): 19.050 MM
    COVER (BOTTOM): 19.050 MM TH: 400.000 MM
    59 TOP : Longitudinal direction - Only minimum steel required.
    59 BOTT: Longitudinal direction - Only minimum steel required.
    59 TOP : Transverse direction - Only minimum steel required.
    59 BOTT: Transverse direction - Only minimum steel required.
    59 TOP : 0.800 39.54 / 4 0.800 5.35 / 5
    BOTT: 0.800 2.64 / 3 0.800 0.04 / 1

    how to interpret these results.


    Thanks in Advance.