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Recent content by AggieYank

  1. AggieYank

    Miami Pedestrian Bridge, Part I

    Given the end result, where people lost their life, this is an inexcusable and unacceptable result. Having said that, something to consider: If you have never worked for a contractor or on a project where you are responsible for project execution, then consider that something that appears black...
  2. AggieYank

    Miami Pedestrian Bridge, Part I

    If the "pipe stays" were indeed almost cosmetic, then it bothers me a lot that all of the diagonals of the truss were aligned with the stays, instead of given simpler geometry.
  3. AggieYank

    Miami Pedestrian Bridge, Part I

    From looking at drawing package erection procedure (page 125): Link * They were supposed to tension the strands in the longitudinal direction prior to setting main span and removing shoring. * It was planned to set the main span, and 2nd span, and only then install the guys (which were 16"...
  4. AggieYank

    HSS Shear Lugs

    Edit: I understand the question is regarding a shear tab. Bottom of shear tab can't "push in" the tube given the grout inside. But, top of shear tab will "pull away" from tube, and you'll be relying on the grout in tension, right? Like below image?
  5. AggieYank

    HSS Shear Lugs

    Is that supported by code? Then OK. If not, then I'd check the flange for the same criteria as if it wasn't grouted. As an academic consideration: If the HSS wall was really thin and a shear tab was highly loaded and wanted to rotate the HSS wall outwards, then 2" of unreinforced grout...
  6. AggieYank

    Miami Pedestrian Bridge, Part I

    Its a cable stayed bridge, that weighed 940 tons (if we can accept that the news reporting is correct). If the bridge was designed for 100psf of traffic on it, that is an additional 340 tons approximately. So, dead load is by far the dominant load. Without knowing project details, it seems...
  7. AggieYank

    Direct Analysis Method K=1 verus Euler Buckling Strength Equations-Consistent logic?

    Josh and Koot, thanks for reinforcing the idea that the K=1 method is just a simplified conservative way of checking against the Direct Analysis Method Output results, and that i am not simply missing something about trying to understand the K=1.: It will be interesting to see what future AISC...
  8. AggieYank

    Steel Pricing

    HSS tubes are a slight premium to round pipes for equivalent weight, as long as the pipes are "normal" sizes. "Normal" round pipe sections are cheaper than non-standard. I would consider the even-number-sized pipes to be "normal", and the odd-size pipes to be unusual. So, a 4", 6", 8" pipe...
  9. AggieYank

    Direct Analysis Method K=1 verus Euler Buckling Strength Equations-Consistent logic?

    I understand that Euler buckling load = the load at which a purely axially loaded column becomes unstable, meaning that any lateral load applied to the column would result in huge flexure and flexure deflection. Euler buckling equations use the “effective length” to define the buckling length...
  10. AggieYank

    Flagpole Steel Column - K=1 for all cases?

    Thanks for the replies. Relating euler buckling stress to second order effects inducing small moments is where I get lost. I understand that Euler buckling is different than having axial force on a shape with a small bend. Euler buckling is related to what the shape would look like in the...
  11. AggieYank

    Flagpole Steel Column - K=1 for all cases?

    Say a steel pipe has rigid (moment) base, and cantilevers up 10 feet. A 5 kip weight is vertically attached at the top. For all load cases, is K=1 as long as you use Direct Analysis Method to determine the forces? In other words: For "Dead load only", "Dead + Wind", etc: Because you are...
  12. AggieYank

    Wind Loading on Open Arch Structure

    ASCE 7 is where to find wind loads for various structures. There is something to be said for providing a reasonable product at a good price. However, in the case of your situation: The company that provides the structure should be giving you reaction loads to design for. They should not just...
  13. AggieYank

    Wind Loading on Open Arch Structure

    That fabric is tensioned. This tension will impose loads on your steel. The wind loads you design for need to match what will actually happen in the field. You need to confidently determine what those loads might be. If you aren't comfortable or don't have an experienced person you can work...
  14. AggieYank

    Plastic Modulus vs Elastic Modulus for Steel Design

    For beam design, the green ASD manual used the elastic section modulus S for steel design. The 13th AISC edition uses the plastic section modulus Z for steel design. So you're getting an extra strength capacity per the new code, which relies on the "outer" fibers yielding until the whole...
  15. AggieYank

    Cracks in Flat Plate Slab

    hokie, what is the problem with pouring the top lift of the column monolithically with the slab. I would assume that would be preferable.
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