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  1. duckhawk

    Manager Says Keep the Restraints — I Think They’re Unnecessary. Who’s Right?

    In my opinion there is a big difference between hanging off a railing and hanging off a railing with somewhere to put your feet below it. As long as image 2 has anchorage and a foundation designed to take moment, i don't see an issue with it. There are structural analysis softwares that allow...
  2. duckhawk

    Learning Structural Connection Types – Pin vs Fixed (Real World Example)

    Looks like only one of these is stable.
  3. duckhawk

    Tension/Bending Checks for C shape in weak axis

    If you have a steel manual available, J4 and J10 in the spec would probably cover a lot of needed checks.
  4. duckhawk

    Valid Pin Boundary Condition?

    Appreciate everyone's responses! I think I get what's going on a little better now. Here is the moment force diagram considering boundary conditions pinned. Units are in kip-in
  5. duckhawk

    Valid Pin Boundary Condition?

    For a square moment frame, do you think this is a valid pin boundary condition at the base? Where does the moment go?
  6. duckhawk

    Regarding expanded metal sheets

    @kaffy - see attached. This is from 2017 and may be outdated, their website should have a current version of this.
  7. duckhawk

    Regarding expanded metal sheets

  8. duckhawk

    Regarding expanded metal sheets

    Usually the manufacturer of the expanded metal grating will provide design tables that correspond to the types they sell. It seems like a component that would be analyzed with FEA instead of a design guide, but could be wrong. I know a certain company that uses expanded metal grating for...
  9. duckhawk

    Seismic design base shear to ASCE7-16

    Sounds like the approving authority wants the foundations to not govern the design.
  10. duckhawk

    Is it possible to build classic precast pre-tensioned data centers in seismic zones ?

    Here is a precast company that says they have built many precast data centers. They list the states that they built them, and none of them are in high-seismic zones.. https://www.metromont.com/precast-concrete-data-centers/
  11. duckhawk

    Weld Size Calculation for Plate Welded Perpendicularly to RHS Beam

    If you have a steel manual, equations are given in Chapter J section 4. Like kingnero said, don't consider the horizontal welds, only consider vertical welds. This is a conservative approach. First, required force for each weld needs to be calculated. This can be as simple as dividing Force by...
  12. duckhawk

    Truss Top Chord Lateral Support

    That looks like the only way to take care of laterally bracing the top chord of a warren truss.
  13. duckhawk

    Truss Top Chord Lateral Support

    Sounds like you are talking about a "pony" truss where the top chord does not have direct lateral bracing, but is indirectly laterally braced by vertical truss members. For a pratt truss there are papers written how you can calculate a modified K factor for the top chord to use based on the...
  14. duckhawk

    ASCE 7-16 15.4-6 - Approx. Seismic Period Follow Up

    Appreciate you sharing those experiences. It brings a very polished software down to what it really is - something made by people.
  15. duckhawk

    ASCE 7-16 15.4-6 - Approx. Seismic Period Follow Up

    Appreciate everyone's responses. The structure is a trussed tower with equipment on it.
  16. duckhawk

    ASCE 7-16 15.4-6 - Approx. Seismic Period Follow Up

    This is a follow up question to the thread from 6/4 about ASCE 7-16 15.4-6 The commentary about the equation says to use lateral forces to determine deflection. However, wouldn't you need to consider dead load in that load combo as well when deflection is calculated? Asking because I've ran...
  17. duckhawk

    Welded connection under loads in 3 directions

    Based on "Eccentrically Loaded Weld Groups" in Part 8 of the steel manual, I think you could do SRSS in 3D for all your loads, calc what the angle is between the resultant and weld axis, and then check the weld with equation J2-5 in the steel manual. If moment is to be transferred through that...
  18. duckhawk

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    Turns out I was using wrong units for deflection.. when the right units are used, the Rayleigh method works and matches RISA, as JoshPlumSE stated above. Also, I can confirm that applying 1 lateral load at a time and getting corresponding deflections is incorrect. The correct way is to apply all...
  19. duckhawk

    Crazy cantilevered steel deck

    Nah. I'd prefer the cantilever to come from a long beam connected to the framing of the house, not a couple of 4-bolt baseplate connections.
  20. duckhawk

    ASCE 7-16 15.4.4 - Approximating Seismic Period

    Here is an example problem with the Rayleigh method. In this example, it says all loads are considered in 1 load case, then the deflections at each level are determined. This seems to be the answer. This is opposed to the original method of applying 1 load at a time...

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