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  • Users: ludvik
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  1. ludvik

    I am currently trying to determine

    I am currently trying to determine the plastic hinge properties of a bridge pier with precast post tensioned segments. Plastic hinges will form at the base of the piers under high seismic loads, and I am trying to perform a pushover analysis. There is plenty of guidance out there for...
  2. ludvik

    Post tensioned concrete plastic hinge

    I am currently trying to perform either a pushover analysis or non-linear time history of a bridge with precast post tensioned piers. Plastic hinges will form at the base of the piers under high seismic loads, and I am trying to determine the properties of this hinge. There is plenty of...
  3. ludvik

    California PE Exam

    Does anyone out there have there have experience with the CA PE? Because of the peculiarity of my situation, I have the option of taking the PE pretty much anywhere in the country except where I live (NY). I am a seismic guy by profession, so taking the additional California seismic portion of...
  4. ludvik

    Battered piles under seismic conditions

    I have recently been told that battered piles do not perform as well as straight piles under seismic conditions. Why is this? The only justification that i have been able to find is that battered piles are stiffer laterally than straight piles and thus attract more load. They have greater...
  5. ludvik

    Ritz Vectors in Linear Modal Time History

    I have a linear FNA (modal integration) time history in SAP2000, and I am trying to define the starting ritz vectors. I have some damping elements at my foundations which model the foundation stiffness and damping. Do i need to give starting ritz vectors for these damping elements, or are the...
  6. ludvik

    Steel Fibers in Concrete Slab

    I have a concrete slab on grade in an electrical substation I am designing. The slab is 9" thick, reinforced with two layers of rebar, and 4000psi grade. The substation will have heavy equipment rolling across it once in a while - the equipment is heavy, (~5kips) and has small steel...
  7. ludvik

    Control joints in slab on grade

    I have a slab on grade in an industrial structure, and I am trying to figure out where to put my control joints. The slab is 9" thick, and has two layers of reinforcing, each with #5 bars on a 12in grid. The slab is continuous with the strip footing around the perimeter of the building for...
  8. ludvik

    Making an excel macro available to all workbooks.

    Dear Forum, I have written a macro in excel which has usefulness to my work in a wide range of applications. I would like to have a button on my toolbar to invoke this macro from any workbook. Currently I have the macro written in its own spreadsheet, and whenever I invoke the macro from my...
  9. ludvik

    Electrical Substation Design

    I am about to start the design of an electrical substation in Jersey City, NJ. I normally design bridges to AASHTO, and am having a little bit of trouble navigating the building and electrical standards. The structure is single story of probably reinforced CMU design. We have been told by the...
  10. ludvik

    ADINA pre & post processors

    Does anyone know of any third party pre and post processors for ADINA for structural applications? The pre/post processors that come with it are sub standard, and we would be interested in something like Hypermesh or ANSA. Michael
  11. ludvik

    Combined soils and structure model

    A major part of structure's behavior under EQ conditions is in the foundations, yet structural models represent their foundations very crudely. I am currently working on a model of a bridge where the first mode of vibration is essentially the structure is remaining rigid, and the entire mass is...
  12. ludvik

    resonance

    Just a basic question. In terms of an electrical circuit, what is resonance? Has is got something to do with the capacitors in a circuit? Is that anything like structural resonance in a beam or something? I am a structural engineer and I guess I'm just curious about what you electrical guys do...
  13. ludvik

    Structural Software

    I work for a firm of consulting structural engineers, and we are currently a little fustrated with the software we use for structural analysis (we design bridges mostly). We use LARSA, SAP2000, and ADINA. LARSA's non-linear time history (ie transient analysis) doesn't work at all. Additionally...

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