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  1. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Thanks for the comfort. Me and my colleagues usually design only maximum of 13 feet beam span connected directly to columns. I didn't have prior experience working with long beam span connected beam to beam. We don't have confidence when beam span go above 13 feet as the deflections, moments...
  2. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Hokie66. I shared details of the center girder connection due to the fact I noticed a hairline crack below it yesterday. It just formed this week and gave me the horrors. Prior we were discussing about the beam-girder connection at one end only. This time, there is a crack at the center girder...
  3. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    I'll explain the extra top bars in detail. First please look at my layout: I designed a 2-storey warehouse, the girder at center is 16.4 feet side to side of building and a vertical secondary beam that frames at the center of it. The secondary beam from back girder to center girder is 18 feet...
  4. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    The reason the supported beam has so much top reinforcement is just redundancy. It only costs a little for the two extra bars. I know just 2 bars is sufficient as the moment there is little as it is the end joint of a continuous beam. Going back to the cracks. If is is flexural cracks, why the...
  5. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Ingenuity, How does such cracking from your description "Such cracking occurs across the supporting beam (girder) interface due to the abrupt section prop change, coupled with the stirrup placement." actually occur? related to Torsion? Shrinkage from temperature? What is the step by step process...
  6. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Yes, hairline cracks across the supporting beam on either side of the supported beam. If it is flexural cracks. Why form right there at the interface instead of at middle or elsewhere? Have you seen anything like it before in your beam-joint design, Hookie? What cracks have you commonly...
  7. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Hookie, please see images of the joint I designed which gave me great concern as it doesn't have the internal hanger stirrups. Earlier in this thread, I posted the hairline crack below the joint. Here is the file photo of exact bar details of the joint. Have you designed anything like it? How...
  8. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Where exactly in ACI is this provision mentioned? Nonetheless, according to fellow poster JAE, millions of buildings are built without any hanger reinforcement in beam-girder joints. Maybe millions of buildings are really in danger? Why is ACI not distinct on this requirement? How do you...
  9. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    The drawing of the compression fan attached (from Mcgregor presentation of the 1984 Canadian Concrete Code 6-29) illustrated my description above. If there is no compression fan (no diagonal inclined cracks). Would the load still be dispensed 45 degrees toward the bottom of the girder or would...
  10. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    I think we missed something. Internal Hanger stirrups are only required if V (shear) at the end of the supported beam is beyond a certain threshold that can cause diagonal cracking. Dolan Et Al mentioned "Hangers will also be unnecessary if the factored beam shear is less than 0.85Vc (as is...
  11. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    Quantify "a lot of longitudinal reinforcement". For instance, in midspan of a supporting girder are 3 #3 (3/8") main bars with a beam with 2 lower bars of same size framing into it. Supposed the 2 beam bars only rest on 2 of the girder lower bars. Won't the 2 girder bars reach yielding strength...
  12. NeilL286

    I-beam Under Concrete Beam

    I plan to reinforce a girder beam (there is another beam framing into it at midspan) due to our codes not enclosing the concept of 45 degree compression struts in beam-girder joints and lack of internal hanger stirrups requirements I mentioned in the another thread. I will use a 12x12 I-beam...
  13. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    It's not in the codes and even my colleagues haven't designed internal stirrups in the beam-beam joint. But I noticed hairline cracks underneath it. Please see. http://img713.imageshack.us/img713/7444/zdz1.jpg Owing to unfamiliarity with 45 degree compression struts in the joint. Colleagues...
  14. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    No one designs beam-beam joints with internal stirrups here? Maybe most misses the crucial aspect of it. Here are the exact details. According to the book "Design of Concrete Structures" by Arthur Nilson, David Darwin Charles Dolan (and illustration attached): "Commonly in concrete...
  15. NeilL286

    Hanger Stirrups in Beam-to-Girder Joints

    My co designers at office just determine if the girder portion where beam frames into it has sufficient V to resist the shear of the beam. They assume the reaction from the floor beam is more or less uniformly distributed through the depth of the interface between beam and girder. But in...

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