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Recent content by darkjmf1

  1. darkjmf1

    Cracked inertias for static analysis

    Hello, ACI 318-19, cl. 6.6.3.1.1, provides reduced inertias for different structural elements. It's clear to me that these values have to be considered for a lateral deflection anlysis, but should they be used as well for obtaining the design forces of those elements in a static (not seismic)...
  2. darkjmf1

    Modelling and design of basement walls

    Good afternoon, Being an advanced user of SAP2000 I am starting right now with ETABS because of its design capabilities for concrete walls. I have found plenty of information regarding shear walls, but not so much about basement walls. As far as I have understood, shear walls design is based...
  3. darkjmf1

    Steel Frame Design. Unbraced length ratio (K)

    Hello all, I have been using SAP2000 Steel Frame Design (SFD) for a bunch of years now but there has always been something going inside my mind about the values of unbraced length ratio (K) calculated by SAP. Depending in the way you model the frames of a column, the results are quite different...
  4. darkjmf1

    ACI 318-14. Minimum reinforcement in cantilever walls

    Thanks for your quick answer, rapt! According to that, wouldn't be necessary any minimum reinforcement at all in the compression face? But in the case of a basement wall (with slab at top) where both faces at tensioned (inside face at middle height and soil side at the base of the wall), we are...
  5. darkjmf1

    ACI 318-14. Minimum reinforcement in cantilever walls

    Hi all, ACI 318-14, cl.11.7.2.3, says: "For walls with h greater than 10 in., except basement walls and cantilever retaining walls, distributed reinforcement for each direction shall be placed in two layers parallel with wall faces in accordance with (a) and (b): (a) One layer consisting of at...
  6. darkjmf1

    Anchor bolts shear transfer

    I like that approach but, according to ACI 318 and as said in my OP, the failure mode described as Case 2 assumes that the total shear have to be resisted on the rear row of anchors. It is my understanding that it does not literally mean the last row, but any other row than the first one. In...
  7. darkjmf1

    Anchor bolts shear transfer

    Sure that increasing Ca1 results in a bigger value of Vcbg, but not enough to compensate Vu, so at the end of the day I will need supplementary reinformcement anyway. And I will have to face my original problem: designing a horizontal reinforcement for the total value of Vu.
  8. darkjmf1

    Anchor bolts shear transfer

    But my original concern remains: How come that a section which is not required to have shear reinforcement is obliged, due to the anchor shear design, to provide such an amount of shear reinforcement? At least when you calculate a shear reinforcement for the whole section you take into account...
  9. darkjmf1

    Anchor bolts shear transfer

    Hello, I am having some concerns regarding the shear transfer mechanism of anchor bolts. Let's say I have a (real big) pedestal (1400x5400 mm, f'c=25MPa) supporting a base plate anchored by 27M56 (Fu=410 MPa) and resisting a factored shear Vu=3600 KN (see attached sketch). Code is ACI-318-14...
  10. darkjmf1

    Are minimum reinforcements additive?

    You are so inquisitive! [wink] I have been talking all the time about architectural reasons to make it simple, but there is no meddling architect. There are two of these beams which support a huge generator, and our client do not want to modify any dimension of the design provided by the...
  11. darkjmf1

    Are minimum reinforcements additive?

    Ok, KootK, I didn't want to assault you all with the details, but as you insist[wink], there you are: Beam dimensions: 2010 x 1550 mm (width x height) Concrete: f'c = 25 MPa Steel: Fy = 400 MPa Ultimate forces acting on the beam (the complete set, not only torsion), at midspan: M vertical =...
  12. darkjmf1

    Are minimum reinforcements additive?

    As I said in the original post, the problem here is that the beam is oversized due to architectural reasons. My first thought was to reduce sizes so the As,min would not gobern the design of the reinforcements, but I was not allowed to. Is not there in ACI any clause for these situations? I am...
  13. darkjmf1

    Are minimum reinforcements additive?

    I am really enjoying this post! Although it seems that there is not a simple answer to my initial question, I thank you all for the vivid discussion. I am learning a lot from it. I am far from being an expert as many of you are, but my understanding was in line with the last message from...
  14. darkjmf1

    Are minimum reinforcements additive?

    For sure forces/stresses are additive, but ACI explains that the purpose of minimum reinforcement is to avoid sudden failure after initial crack. In the (worst) case that both cracks due to flexure and to torsion appears simultaneously, can't we assume that, as long as the final amount of...
  15. darkjmf1

    Are minimum reinforcements additive?

    Of course I intend to add both reinforcements to the beam, but I am concerned about the minimum. Let's try to explain it with numbers: - Flexural: As,req=5. As,min=10 (at the tension side). - Torsional: Asl,req=7. Asl,min=11 (let's say that the total reinforcement is equally distributed at...
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