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Recent content by SandwichEngine

  1. SandwichEngine

    PEMB Zee and Cee Purlins

    I'm a PEMB guy. For wind loads, there shouldn't be any weak axis load because that load always acts normal to the roof plane. Snow load is another matter. That will have a component of force normal to the purlins and a component normal to the roof panel. Standing seam roofs are always...
  2. SandwichEngine

    Existing PEMB - Multi Column Removal/Jack Truss

    You guys are correct. The strut forces in the purlins used to be neglected in design. I heard that from an old timer when I started 20 years ago. Hasn't been that way since I started. You don't necessarily need purlin bracing if you have a through fastened roof because the AISI has formulas...
  3. SandwichEngine

    Existing PEMB - Multi Column Removal/Jack Truss

    The comment I was responding to was the one above yours which is about the loading in the direction perpendicular to the rigid frames, in particular if the above fix would suck some load from the bracing system which has nothing to do with the lateral system of the rigid frames. Any experienced...
  4. SandwichEngine

    Existing PEMB - Multi Column Removal/Jack Truss

    I want to add something about the flexibility of PEMB structures--They're much more rigid than you think in the direction perpendicular to the rigid frames due to an abundance of redundancy. Hypothetically, wind load travels from the top of wind columns through strut purlins until it hits the...
  5. SandwichEngine

    Existing PEMB - Multi Column Removal/Jack Truss

    Very nicely done. I'm a PEMB guy. The 8" pipe columns are schedule 40 std 8" pipe. Round HSS is not readily available on the market despite being listed in the steel manual. also the pipe column was definitely designed as pinned-pinned. I jacked out a column supporting (2) 5 ton cranes on...
  6. SandwichEngine

    PEMB buildings from China? Engineering?

    I'm a PEMB guy and I would run. One thing you want to look for with PEMB suppliers is that they are IAS certified. It's the same as being AISC certified for a conventional fabricator. They come in a few times a year and audit your engineering, business practices, and most importantly, shop...
  7. SandwichEngine

    Crane Side Thrust Loads

    The difference in load based on control type is due to speed. Pendant cranes go as slow as a man can walk. Cranes controlled from a control room (radio) go faster and therefore create a larger dynamic load. Cab cranes go even faster and therefore have even higher loads. These days most...
  8. SandwichEngine

    PEMB Shear Breakout

    I'm a PEMB guy. One thing I've seen a lot of foundation engineers get wrong is the direction of the shear wind loads on rigid frames. When you have vertical loads like dead or live, it pushes down on the rafter and the columns want to kick out. The opposite happens in wind loads due to high...
  9. SandwichEngine

    ASCE 7-16 Figure 30.4-1 Shaded C&C Wind Pressures

    Is there a chance that the book is working in ASD? If so, the minimum design-level load would be (16 psf)*(0.6) = 9.6 psf.
  10. SandwichEngine

    Reduction in Strength of epoxy anchors based on reduced anchor spacing

    I'm in a hurry but I believe the ACI code gives the required spacing but makes exceptions for products with tested values with closer spacing. If you free download Simpson Strong Tie anchor designer, I know it will allow about 4db for many of the epoxy anchors, depending on diameter. I presume...
  11. SandwichEngine

    built up beam

    You might find help in crane beam design resources. They are usually some type of built up section due to the need for strength in both directions. Crane-Supporting Steel Structures by R.A. MacCrimmon is a great resource with design examples. You can get it free. Just google Canadian crane...
  12. SandwichEngine

    USGS/ASCE Web-Based Tool for Seismic Site Classification

    https://ascehazardtool.org/
  13. SandwichEngine

    Pre-engineered Columns for Compression

    Your results sound off to me. Are you considering the girts and flange braces as weak axis restraints for bending and compression?
  14. SandwichEngine

    PEMB frame deformation due to foundation settlement

    These things can bend a lot in their weak axis without yielding. If you can get it straightened out and nothing has yield line, then it's remained elastic. https://youtu.be/V7zOZbCQ94M?si=qPRy6IQNFzt9Jw8p I'm guessing a PEMB erector would be a good resource for how to get the rafters back to...
  15. SandwichEngine

    Another Structural Software Thread

    Tekla Structural Designer does #2 easily. Haven't needed number 1.
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