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  1. AThor

    Rebar Development Wall to Diaphragm Connection

    Thanks for the reply lexpatrie. I agree, embedded images are nicer than links, I just don't know how to do that. Would someone mind giving some quick instructions on how to do that? Agree, the bars need to be developed for fy on either side of the shear plane (the cold interface between wall...
  2. AThor

    Rebar Development Wall to Diaphragm Connection

    Thanks for the replies, each gives me some justification, from three different angles. I will add the longitudinal bar, that makes sense and is easy enough. Referencing the IEBC also makes sense, this is just a minor repair. And I'm glad to see a similar detail in an ACI publication.
  3. AThor

    Rebar Development Wall to Diaphragm Connection

    Okay, I have been puzzling over this all day, and after pouring through ACI 318, Hilti, and other Eng-Tips threads, I finally decided to just ask. I am replacing an existing concrete roof slab in a simple building with 6" concrete walls and roof. The attached detail shows the planned replacement...
  4. AThor

    Concrete Border On Grade Next To Trench Wall

    Thanks for the replies, good ideas. I would think the tunnel should be fine for vertical loads, since it won't be any different than it sees now with the current lid configuration. I'm not sure about what new lateral loads the border beam might cause, I'll have to think about that.
  5. AThor

    Concrete Border On Grade Next To Trench Wall

    I was hoping to get some thoughts on the following situation. We are designing some work inside concrete walled trenches, and there are some concrete lids being replaced. In the process of replacing the lids, the contractor has to demo the surrounding asphalt surface back a few feet, and...
  6. AThor

    Structural Theory Question Regarding Fixed/Pinned Ends

    Thanks for each of your contributions. The points I quoted below help make it clearer. My next question was going to be, "is it common, or acceptable, for parts of a connection to go plastic, assuming the beam design only needs a simply supported end?". I did a quick google search and found this...
  7. AThor

    Structural Theory Question Regarding Fixed/Pinned Ends

    Thanks. Enveloping the design for worst case assumptions certainly makes sense and seems like a good approach in a lot of situations. I'm just trying to better understand what's truly going on, both for situations where I am analyzing something existing versus designing something new, and to be...
  8. AThor

    Structural Theory Question Regarding Fixed/Pinned Ends

    Thanks for trying to decipher my post. You are right, the pipe case would be a catenary if the connections are assumed hinges. The real world situation I was getting that example from is a floating debris boom with HDPE pipe, so we actually do want a catenary. It turns out that as the total span...
  9. AThor

    Structural Theory Question Regarding Fixed/Pinned Ends

    Hello, I would like to get some responses about a theoretical question I have been wrestling with on numerous occasions. I think understanding the underlying concepts better would help clarify a lot of things in my head. I've attached an illustration of two recent problems that relate. Case 1 is...
  10. AThor

    Pipe Hanger Seismic Analysis - Moment in Rods?

    Thanks for all the input, this discussion is helpful. Strucbells, that sounds very similar to my situation. The detail has unfastened pipes, and only lower tier braced trapeze beams. It could be a two wrongs making a right situation, but I'm skeptical. If we don't have the pipe weight as part of...
  11. AThor

    Pipe Hanger Seismic Analysis - Moment in Rods?

    Thanks for the replies. That's a good summary bones. I have just read through the Unistrut examples, and I also found this reference from Kinetics Noise Control that I'm going to post here for any future users who come across this thread, because it gives a good explanation also...
  12. AThor

    Pipe Hanger Seismic Analysis - Moment in Rods?

    I am trying to understand and analyze a detail for a hanger support with seismic brace for a run of multiple pipes. The pipes are sitting on beams that are held up by threaded rods, coupled to anchors embedded in the concrete above. So far in my career I have not managed to fully wrap my head...
  13. AThor

    Tank Anchorage, Overstrength Factor, and Overturning

    I am not designing the tank or saddles, just the anchors for a pre-manufactured tank. So, when I say I assume the slots are okay for the thermal expansion, I mean that I assume the tank manufacturer designed it correctly. Although to your point, it might not hurt for me to do an expansion...
  14. AThor

    Tank Anchorage, Overstrength Factor, and Overturning

    Those arguments certainly makes sense. On the other side of the argument, there is the 15.7.5 commentary, which says "Where tanks must be anchored because of overturning potential, proper anchorage design provides both a shell attachment and an embedment detail that will allow the bolt to yield...
  15. AThor

    Tank Anchorage, Overstrength Factor, and Overturning

    Thanks all. Oldrunner, the tank itself has slotted holes on one saddle base, which I assume will mitigate any thermal expansion loads. So, I have not considered those in my analysis. bones206, I tend to agree with you, which is why I made it option a) in my original post. But, do you have a...
  16. AThor

    Tank Anchorage, Overstrength Factor, and Overturning

    My question relates to ASCE 7 Chapter 15, particularly 15.7.5. I am designing the anchorage for a saddle supported liquid storage tank. Section 15.7.5 makes it clear that the overstrength factor is NOT to be used for tank anchorage calculations, because they are trying to force a ductile yield...
  17. AThor

    Friction Contribution to Lateral Force Resistance

    Yep, that's the gist I'm getting. By the time you factor in the unknown coefficient of friction, the vertical seismic uplift effects, and dead load factor 0.9, the friction effect is almost negligible, so might as well just treat it as a small extra safety factor. Thanks for all the quick...
  18. AThor

    Friction Contribution to Lateral Force Resistance

    Yeah, Det, I think you're right, the "permanently attached to a structure" phrase kind of makes Chapter 13 not applicable. I am not as familiar with chapter 15, but I think equation 15.4-5, for rigid nonbuilding structures might be most applicable. Interestingly, that equation is 0.3Sds*Ie*W...
  19. AThor

    Friction Contribution to Lateral Force Resistance

    Yeah, that's true. I'd have to factor in the 0.2Wp vertically, and use the load combinations with earthquake forces that have a 0.9 load factor on dead. So after that, the friction contribution would be fairly small, especially since I'd probably have to use a conservative coefficient of friction.
  20. AThor

    Friction Contribution to Lateral Force Resistance

    Thanks @DET, that makes sense. As a follow up question, when you're calculating the component seismic force, what do you use for z/h when you have an object like this box, or temporary bleachers, or anything sitting on a ground surface not really connected to a building. I had just been using...

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