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  1. JoshPlumSE

    pre-qualified beam-to-column corner connection "calculations" in structural steel OMF?

    There's still OMF requirements to be followed: a) The connection still needs to be designed to the "probable plastic moment". And, the shear strength requirement based on developing that probably plastic moment. b) Alternatively (as discussed in the code commentary) you can design the...
  2. JoshPlumSE

    RC stairs conection with RC foundation slab

    I have two totally contradicting opinions on this: a) That could be a way to keep the lateral forces out of the stairs and keep in them in the main lateral force resisting system. For me, that seems to be a struggle with a lot of commercial buildings. Keeping the stairs connected to the...
  3. JoshPlumSE

    Gyp Board Shear Walls for Multi Story Apartment Building

    Ugh. I personally hate the idea of relying on Gyp board for lateral resistance. The only time I've seen this done is when someone had an existing structure and they wanted to justify why should be allowed to do a renovation even though the lateral system didn't calc out.... Heck, I believe the...
  4. JoshPlumSE

    High Rise Builiding Modal Mass Participating Ratio

    No image attached. Also, if this is an academic question. It's probably best posted in the "Student Engineer - General Discussion" forum. Some people get annoyed at students posting homework questions and the like....
  5. JoshPlumSE

    [WOOD] In plane force distribution based on 4.3.5.5.1 exception

    We do agree. I just wanted to clarify the "rigorous analysis" part of your comment. Meaning there are many different forms of a "rigorous" analysis engineer might use that still wouldn't properly capture the softening effect of the high aspect ratio walls.
  6. JoshPlumSE

    [WOOD] In plane force distribution based on 4.3.5.5.1 exception

    I'd state it differently. I don't think a "rigorous analysis" does a very good job of accounting for how much more non-linearity you get from a skinny shear wall. Elongation of the hold downs and such. Now, I'm sure the CURREE folks who did all the testing can come up with a rigorous non-linear...
  7. JoshPlumSE

    Is W6x20 a normal section used for Columns? Especially in Hurricane zone

    You'd have to talk to a contractor.... The ones I've spoken to hate those small sections. That's not a very large sample size. My superiors (earlier in my career) and most engineers I've spoken to have all had similar bias against them. To varying degrees. Companies I've worked for have used...
  8. JoshPlumSE

    Is W6x20 a normal section used for Columns? Especially in Hurricane zone

    I don't see W6's used for any substantial structure. Not even for stairs. Maybe minor equipment support frames. You know the type where you've got a piece of equipment that needs to be elevated, but doesn't have much load. Maybe equipment skids. Maybe some short augured piles where you drop a W...
  9. JoshPlumSE

    Force Transfer around Garage Doors and even bigger

    1. What method do you use to calculate strap force for a garage door scenario? **I use anchors at any full height openings. If you do this then Force Transfer Around Openings (FTAO) still applies and can still help reduce anchor forces due to 'frame action' of the wall when compared to an...
  10. JoshPlumSE

    Back-to-Back Shearwalls

    I don't think there is anything against it. From a practical standpoint you might have anchorage issues..... meaning overlapping pullout cones for your headed anchors. Which will tend to make your anchorage less efficient. In a case like this I might use a structural plate connecting the two...
  11. JoshPlumSE

    Wood shear wall design

    I certainly agree that this is the best book for the "unusual" situations. Very thorough and logical procedures for the cases we look at and say, "how am I going to handle that!?". However, for basic shear wall design, I think it's way, way, way too complicated. Honestly, I feel like the NDS...
  12. JoshPlumSE

    Effects of member offset on story drifts

    That is totally normal, but shouldn't be done with steel frames. For concrete, use of the offsets may get you closer to the "real" elastic drift. For steel, you technically need to account for panel zone shear deformation (which few people do). Thankfully, most people will accept the idea that...
  13. JoshPlumSE

    Is it possible to exclude certain parts of framing from being designed as part of SMF?

    Yes, this is very common. The way the "gravity only" portion of the structure connects to the lateral force resisting needs to be sufficient to transfer it's inertial forces into the SMF. And, sufficient enough to accommodate whatever lateral deflections occur in the overall structure due to...
  14. JoshPlumSE

    Masonry

    I'll 2nd JedClampet's recommendation of Amrhein's "Reinforced Masonry Engineering Handbook". That is the best masonry book I have seen. It is a bit out of date, but it's still a very good place to start to understand the basics of masonry design. Some other recommendations: Obviously, you...
  15. JoshPlumSE

    Shear transfer through diaphragms

    I wouldn't call it the "bible" of wood diaphragms, but it is an excellent reference. It forces you to think logically about load paths for irregular shaped diaphragms. How it affects shear and detailing around corners and such. Kind of like doing force transfer around openings for shears walls.
  16. JoshPlumSE

    APA Portal Frames at Story 2-5

    Can anyone explain to me how this is different than what's described in the NDS document Special Design Provisions for Wind and Seismic related to Perforated Shear walls and / or Force Transfer Around Openings? Is this document more geared towards "non-engineered" structures?
  17. JoshPlumSE

    Shear transfer through diaphragms

    Yes, and for cases like this (where there is discontinuous load path, you want to use the Omega type seismic loads to detail the transfer of shear from the upper shear wall into the diaphragm.
  18. JoshPlumSE

    Mixed SFRS

    I wasn't familiar with this section. But, that is really good news. Makes a lot of sense for light frame construction less than two stories.
  19. JoshPlumSE

    Mixed SFRS

    IMO, there are a couple of ways to look at it: 1) Standard code way: Where the R value for the whole structure (at least at that level and above) would drop down to 2.0. Ouch! 2) Using Performance Based Design. Meaning pushover analysis or such. The idea being that if you want to...
  20. JoshPlumSE

    Equivalent Horizontal Force and P-Delta effects

    The RISA manual has a good description of how they use secondary shears (equal and opposite) to create the destabilizing P-Delta moment while maintaining equilibrium. https://risa.com/risahelp/risa3d/Content/3D_2D_Only_Topics/P-Delta%20-%20Analysis.htm

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