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Recent content by m_ridzon

  1. m_ridzon

    Eigenvalue Buckling

    I'm currently working on an overhead, underhung crane. But my buckling question was more high level and not specific to a particular structure. The ANSYS Help Documentation says the following. These statements have always made me pause when I consider using the Eigenvalue Buckling solver for...
  2. m_ridzon

    Eigenvalue Buckling

    Folks, I just have a high level question about the ANSYS Mechanical Eigenvalue Buckling solver. It has always been my understanding that the Eigenvalue Buckling solver is a low-fidelity first-pass glimpse of a structure's buckling characteristics. In other words, use of the solver should not...
  3. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    In weldment design, is it common to screen out welds on the basis that they are not loaded heavily and do not need an explicit sizing evaluation? In other words, if the weldment has hundreds of welds, large and small, is there a method to screen out some of them to reduce the amount of weld...
  4. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    Yes, that's a great point and the thought has already crossed our team's mind. We are closely collaborating with the customer (they are more experienced with crane design), and our hope is that we can all reach a consensus together, where we all feel comfortable that the FEA is producing...
  5. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    I had a feeling my post would elicit at least one response like this. It's not very productive in terms of the actual question(s) I posed at the beginning. Folks, I sense the cynicism and it's not very productive. I mentioned earlier in the thread that FEA needs to be used because of the...
  6. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    Hmm, I'm confused on how a less-accurate modeling method (i.e., plate elements) would produce better correlation with hand calcs. I'm also confused on how the rigidity of the plates play a part in the calculation. Blodgett does not mention the thickness of his plates. Potentially, they could...
  7. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    I'm modeling solid bodies. I wanted to do plate elements, but I was concerned the correlation between FEA and hand calcs would be worse. So I was trying to prove the correlation to myself first with solids. Later I plan to attempt plate elements. Here are two solid rigid bodies connected...
  8. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    Yes, your inclusion of weld size is correct. In haste, I left that part out, assuming it to be understood. Yes, our team is getting into AISC 360 later. We're starting with the basics in Blodgett though, in that welds can be treated as lines and checked for allowable force/length. We are...
  9. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    In practice, how is this done? I know how to extract loads at the FEA connections. But on a complex weldment, how do I determine what portions of the loads are creating tension, twisting, torsion, bending, etc., to thereby use the correct hand calc equations? Additionally, the extracted FEA...
  10. m_ridzon

    Weld Sizing - Blodgett vs. FEA

    Folks, my project is actually a mechanical engineering project, but I think my question might be suited for this structural forum instead. I've not done much weld sizing in my career, but am now deep into Blodgett's Design of Weldments for an overhead crane I'm working on. It has various...
  11. m_ridzon

    ASCE 7-16 Seismic Design for Skid With Nonstructural Components

    Okay thanks for this additional feedback. I can tell that it's a grey area that can be perceived different ways. But I think I have an idea of what's involved now. Thanks!
  12. m_ridzon

    ASCE 7-16 Seismic Design for Skid With Nonstructural Components

    Yes, I have reviewed 13.3.1.4. It says dynamic analyses are allowed for the building and/or the floor, but you then take the acceleration that was determined from that RSA model and plug it into Eqn 13.3-4 to determine the seismic force for the nonstructural component that resides on that...
  13. m_ridzon

    ASCE 7-16 Seismic Design for Skid With Nonstructural Components

    Okay, thank you for that feedback again. The main debate I'm having with a colleague is whether ASCE 7-16, Chapter 13 allows an engineer to analyze a nonstructural component by directly applying a response spectrum to said component in the modeling software. He believe it's permissible...
  14. m_ridzon

    ASCE 7-16 Seismic Design for Skid With Nonstructural Components

    Okay, that makes sense so far. In the case you generate the "in-structure response spectrum," would you use Eqn 13.3-4 to generate the seismic force for the component? Or can you directly apply the spectrum to the nonstructural component?
  15. m_ridzon

    ASCE 7-16 Seismic Design for Skid With Nonstructural Components

    When designing nonstructural components, is there ever a case where a response spectrum can be applied directly to the nonstructural components in modeling software? Let me elaborate... From my understanding of Chapter 13 of ASCE 7-16, to do an RSA approach, you have to run the RSA on the...

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