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  1. trustthemodel

    Existing Wood Bowstring Truss Evaluation

    From what I recall there were originally bowstring truss catalogs distributed by manufacturers where you would choose a truss based on some parameters like the required span. It sounded like every manufacturer had their own way of doing things but were pretty consistent about it. I believe back...
  2. trustthemodel

    Note for "Field Measurements"

    In addition to having a note similar to what WARrose is showing, we typically say something along the lines of: Contractor immediately notify A/E team of any discrepancies between information shown on drawings noted in the field. ("information" would include elevations, dimensions, construction...
  3. trustthemodel

    Notes

    As others allude to above, structural general notes are typically where CYA notes from past projects are thrown in as a last defense in resolving disputes/questions. These can be vague or detailed depending on what the issue was when the note was created. Unfortunately, the CYA notes aren't...
  4. trustthemodel

    Notes and Tips to Welder

    I never spoke directly with the welders but one thing that had come up in conversations with steel fabricators was welding to provide ductility at simple shear connections. (welds at welded seat connections or welded double angle connections for example) The general feeling I got from the shop...
  5. trustthemodel

    Wind Load Direction for Corner Mullion Condition

    Curtain wall manufacturers typically have engineers which will run quotes for certain jobs. They may be a good resource for the particular system you are looking at considering corner mullions can be odd shapes at odd angles. The same manufacturers also typically have loading tables which may...
  6. trustthemodel

    chemical anchor selection

    Some manufacturers (HILTI, Simpson Strong-tie) have free anchor design programs which allow you to assign forces, connection geometry, etc. and look through anchoring options with their catalog including required epoxy, anchor size, spacing, embedment, etc.. This may be of help for you to choose...
  7. trustthemodel

    isolation of Stainless steel bolts and mild steel plates

    Just wanted to chime in and mention AISC design Guide 27 or ASCE 8 may provide some guidance for the specific application you are considering. From what I recall most recommend insulating washers such as neoprene between stainless steel and carbon steel. However, as others have mentioned, the...
  8. trustthemodel

    Web Local Crippling and Web Yielding

    From AISC Chapter J section 10 the limit states of web local yielding and web local crippling apply to: "single- and double-concentrated forces applied normal to the flange(s) of wide flange sections and similar built-up shapes." As you are connecting to the web of the column I would not...
  9. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    Agent666, The truss was modeled with pin-pin web members with end nodes at the points where web centroids intersected with the chord centroids so that the chords take those eccentric connection forces. On NDS 15.1: If I am interpreting 15.1 correctly it looks like the code would not consider...
  10. trustthemodel

    Maximum Lag Screw Size Penetrating into 2x Main Member

    From what I recall those minimum penetration limitations are just minimums to ensure the applicability of the yield limit equations. That said, I think you'll be surprised to see that assuming a smaller diameter lag screw for the same application may actually give you higher reference design...
  11. trustthemodel

    Slip critical connection

    The AISC Steel Construction Manual would be a good starting reference. Before doing that I would recommend you double check the application and figure out whether the slip critical bolts are really the way to go.
  12. trustthemodel

    Lag Screw length

    From what I recall those minimum penetration limitations are just minimums to ensure the applicability of the yield limit equations. That said, I think you'll be surprised to see that assuming a smaller diameter lag screw for the same application may actually give you higher reference design...
  13. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    BA, The ends of the truss had (2) 3x8 blocks near the saddle which I included in the elevation/truss model as the diagonal closest to the truss ends. To your point, I am not too familiar with bowstring truss construction practices and will look into whether a diagonal might have been missed...
  14. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    Agent666/All, Here is an elevation of the truss we're looking at. https://res.cloudinary.com/engineering-com/image/upload/v1561639439/tips/Bowstring_Truss_cwwwpa.pdf
  15. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    Agent666, Thanks for the reply! I agree, conservative guesses are really the only guesses we should be making. I will follow your advice and look what the office has available for a buckling analysis for these truss members.
  16. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    KootK, Thanks for the reply! 1) The idea was that the compressive capacity of the top chord along its length could be checked using segments of the truss treated as columns which would have unbraced lengths in- and out-of-plane as defined above. The unbraced length in either direction would...
  17. trustthemodel

    Wooden Bowstring Truss - Chord Effective Lengths

    Hello all, I have a couple of questions pertaining to the design of an old bowstring truss, particularly the chords of the truss. Background: - 50's era wooden bowstring truss with approximately 60' span - Truss web members are 3x4 members at the centerline of the truss with chord members to...

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