Learning Forum

[Akua Alder]

I am a final year Masters's Student from Heriot-Watt University currently working on my dissertation project titled "A THEORETICAL ASSESSMENT OF THE STRUCTURE OF A LIQUID STORAGE TANK UNDER SEISMIC FORCES" with the following objectives:

1. Verification of Current Theories (Housner, Preethi, and Malhotra) of liquid Structure Behavior (sloshing wave height) under seismic forces for petroleum-filled storage tanks using Finite Element Modelling and Finite Element Analysis.

2. Assessment of the possible failure mechanism of the superstructure of the various liquid storage vessels under exposure to seismic forces using Finite Element Modelling and Finite Element Analysis based on the API 650 Design Standard.

3. Proposal and initial assessment of the effectiveness of a Bass Isolation System on the sloshing wave height using Finite Element Modelling and Finite Element Analysis.

Can the Ansys modal analysis module be used to model a fluid-filled storage tank and determine the sloshing wave height along with the impulsive and convective mass components of the fluid based on the application of specific Acceleration, Velocity, and displacement values?

Can I subsequently transfer the model to the Ansys Static Structural Module to determine the various resulting stresses that will develop within the tank structure due to the seismic forces and the fluid-structure interactions?

If not, can you guys offer any advice on what methodology I should take?

[Akua Alder]

My current proposed modeling process is to model the fluid-filled tank first and carry out a modal analysis on the model in Ansys Modal Module. Those results will then be transferred to Ansys Fluent to determine the fluid-structure interactions based on earthquake data that I have so that I can determine the sloshing wave heights. I will then link the results to carry out a Transient structural analysis of the tank and finally a response spectrum analysis to determine stresses in the tank body.

[Ram Gopisetti]

HI 

I want to be very specfic to adress an specific issue i.e LIQUID STORAGE TANK UNDER SEISMIC 

you can solve this using the FEA ( ALE, SPH) , we call this to be a slosh simulation but subjected to seismic load. 

this needs an knowledge in the LSDYNA as standard ANSYS cannot work the physis correctly and need an explicit solver than the implicit 

i might not give you all info right away, but the i might give you some clues 

start with an read : https://lsdyna.ansys.com/soil-structure/

we have general two methds to apply the seismic load ( by traction card (BOUNDARY_PRESCRIBED_MOTION) and by acceleration card ( LOAD_BODY)) all needs an ground node with ground acceleration applied to it.

or an specific cards like load_seismic_ cards might be an option 

you need also build an idea on how to model ALE, SPH and thier material modeling and contacts. you are solving an FSI system so you need to know the methods on controlling the coupling and the leakeges in ALE domain. 

this FSI will give all mechnical quantities so no need of extra or supplementry tools neede ( if in dyna) 

your research might open a lot of doors, so start with it.

cheers, ram