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  1. KootK

    shear wall opening in mid floor 2 stories

    Here's one possibility.
  2. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    I would argue that footing depth is largely irrelevant if you're attempting to go down the STM / RC concrete path. That, because those paths require you to anchor your bars within the flexural compression block etc, not within the overall depth of the footing. On the other hand, if one...
  3. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    That, right there, is the fundamental mistake. Assume the following which will be true of most foundations. 1) Not lapping starter dowels with shear rebar 2) Not using anchor plates or extending the starter dowels into local thickenings. Under such conditions STM is not an appropriate design...
  4. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    That surprises me not at all. I've worked for firms of all sizes, including most of Canada's marquee firms. My takeaways: 1) Such firms need to be efficient production shops. To that end, they establish a particular design dogma and push pretty hard for designer to not "waste" a lot of time...
  5. KootK

    Double 3-Sided Roof Diaphragm

    @Celt83 has brought something to my attention that may be relevant. The stuff below is from a Mesozoic era Diekmann publication. I actually disagree that there is a vertical component to the chord forces. The chord forces are just axial in my view. That said, it maybe just a perspective...
  6. KootK

    Double 3-Sided Roof Diaphragm

    No, I don't think so. I started my diatribe with this simple assertion: what matters for load sharing is that both diaphragms experience compatible, in plane displacement under lateral load. Are you in agreement with that? Because, if you are, the answer to your question is right there in...
  7. KootK

    Double 3-Sided Roof Diaphragm

    Thanks for coming back to play. 1) Because they are not designed to provide vertical restraint, not even for gravity. 2) The size of most ridge boards would provide very little vertical stiffness. Heck, some aren't even flexurally continuous. 3) Many ridge boards are not vertically...
  8. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    Yes. But I would argue that your presentation is backwards. It is not the case that, because small hooks are okay, large hooks are okay. Rather, all hooks represent a problem / compromise to some degree. And, commensurately, the larger the hook, the larger the problem. If you imagine how a...
  9. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    I don't know that it does work in the context of the problem being discussed. It does but, as you can see from the model in that ACI diagram, it also creates a significant eccentricity between the line of action of the incoming rebar and what ends up being the node. That setup "works" for the...
  10. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    No, I don't believe that it should be smaller. In my experience, node geometry is independent of bar size / hook "bigness". Yes, and that's precisely what I don't like about it. Bends tend to... unbend. And resisting the tie force out on the bend introduces additional eccentricity. Are...
  11. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    For the same force and node geometry, does anyone really feel that the condition on the right is the better of the two?
  12. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    Ba! That isn't just incorrect, its bass-ackwards. Smaller bars always perform better than larger bars. Activating a strut and tie mechanism in the real world involves a significant amount of cracking and redistribution. Obviously, in such a situation, it behooves one to have tie...
  13. KootK

    Concrete Beam Load Sharing (Tie-Beam to Lintel)

    It just provides shear capacity where it might wind up being needed if the strut materializes. You'd want to have solid shear capacity at both the lower and upper regions of the upper columns so might as well do the whole thing.
  14. KootK

    Concrete Beam Load Sharing (Tie-Beam to Lintel)

    Well, if we're just going stick our heads in the sand about the strutting through the block, I might: 1) Design the upper beam as though the lower didn't exist. 2) Design the lower beam, column, and joint such that they could form a plastic hinge early in the load history. For wind, I don't...
  15. KootK

    Strut-Tie - Tie Development at Nodes (Starter Bars)

    I was referring to your regulatory environment and the standard of care where you practice. In my market, I would consider myself to be at liberty to justify the standard starter bar arrangement by way of methods other than STM, and sometimes not at all. But codes are getting more stringent...
  16. KootK

    Longitudinal shear between web and flange of T-beam

    It could very well be this, what does make sense mechancally.
  17. KootK

    Vierendeel Truss - ASCE Seismic Design Response Coefficient R Value

    I would say that it is definitely not a special truss moment frame. That's a very particular system for a very particular application. I can see why one might be drawn to that though. I feel that conventional moment frame approaches make more sense for something like this. The degree of...
  18. KootK

    Web parallel stiffeners

    Thanks for that. It kind of made my day.
  19. KootK

    Concrete Beam Load Sharing (Tie-Beam to Lintel)

    Unless the masonry is gapped, neither beam will participate in reisting the wind shear flexurally. Instead, you'll develop compression struts through the block that will produce a truss of sorts. Might it make sense to just make these walls solid concrete. I would think that all of the beam...

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