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  1. alishst

    Requesting relevant outputs for base shear and overturning moment

    Hi I've modeled an unanchored tank (shell elements) resting on ground (solid elements). I have given a seismic record to the ground and I want to get the base shear and overturning moment of the tank as my history outputs during the analysis. My question is which categories should I tick when...
  2. alishst

    Dynamic Implicit Application

    Dear FEA way, I tried damping with transient fidelity (brown daigram) and as you can see, there are still plenty of high-frequency, resonant noises in the model. The response for quasi-static (blue diagram) looks more sensible but I'm pretty sure it is flawed as well. What do you think is...
  3. alishst

    Dynamic Implicit Application

    Thanks for the reply FEA way At the moment, there's no contact but might include it later. I am using transient fidelity currently but the issue is there seems to be some high frequency noises added to the outputs I receive. For example I feel there are a lot of (unnecessary) sharp peaks and...
  4. alishst

    Dynamic Implicit Application

    Hi I'm trying to model a 3d liquid tank with acoustic elements and steel shell. I've also used springA elements and a solid mass to serve as a damper. The whole system is subject to an earthquake record. I would like to know which one of these suits this type of analysis better? Transient...
  5. alishst

    Unanchored tank modal analysis

    Hi Is the modal analysis of unanchored tanks (simply placed on the ground) with abaqus any reliable given the nonlinear nature of the problem? I've obtained some results for convective and impulsive modes but don't know if they are any valid or not.
  6. alishst

    Modal analysis for unanchored tank

    I had previously checked API 650 for 2007 but it only has impulsive/convective periods for anchored tanks and doesn't give any separate equation for unanchored (or self-anchored in their own words) tanks. Which edition are you referring to?
  7. alishst

    Modal analysis for unanchored tank

    Hi I'm trying to model an unanchored storage tank using FE software Abaqus. I wanna run a modal analysis and find out the frequencies for main impulsive and convective modes. However, I need some analytical equations for these two in order to verify my results. Is there any design code or...
  8. alishst

    Implicit or explicit analysis for seismic loading

    Hello I want to model an unanchored tank subject to real-life earthquake loading. The problem involves contact and separation between the tank and the rigid ground and also fluid-structure interaction. Should I use dynamic explicit or dynamic implicit step for this purpose? How time consuming...
  9. alishst

    Acoustic-structural interaction in Abaqus

    Thank you again! I have found one example (for a flexible tank this time). I am trying to match my model with the results of that example but my problem is that Abaqus can yield so many modes and I am not sure which one to look at and compare with the example's results.
  10. alishst

    Acoustic-structural interaction in Abaqus

    Thank you Erik! But there's one thing I didn't quite understand in regards with your suggestions. In the last paragraph, were you implying that the assumptions I used in my Abaqus model were in agreement with the Strand7 model you created?
  11. alishst

    Acoustic-structural interaction in Abaqus

    Dear all, I'm trying to model a liquid storage tank using abaqus. The tank is anchored at the bottom and I've modeled the liquid (water) with acoustic elements. I am trying to verify my model by comparing it to results of previous research and experimental studies so I need to extract certain...
  12. alishst

    Modal analysis in a liquid tank using ABAQUS

    Thanks for the reply. I need to provide the first few natural frequencies as a part of a report to compare them with some real-life cases. That's why I wanted to do modal analysis. Do you think purely Lagrangrian elements provide sufficient accuracy for modal analysis? Also another question...
  13. alishst

    Modal analysis in a liquid tank using ABAQUS

    Hello All I'm relatively new to ABAQUS and I am trying to model a liquid tank using coupled Eulerian-Lagrangian (CEL) technique for seismic analysis. My problem is that I cannot extract the natural frequencies and modes of the liquid-filled tank because abaqus/standard doesn't support Eulerian...

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