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  1. li0ngalahad

    AS3600 cl 11.2.1 vs 11.7.3 - Two Layers fo reinforcement in walls

    Not every ultimate design situation assumes zero tensile capacity of concrete, the most evident example being bending capacity of plain concrete footings and pedestals. Anyway, 11.7.3 is a clause that defines reinforcement detailing, not ultimate design, in particular prescribes when 2 layers...
  2. li0ngalahad

    AS3600 cl 11.2.1 vs 11.7.3 - Two Layers fo reinforcement in walls

    ...it, clause 11.7.3 talks about "tensile capacity" not "strength". f.ct is a strenght. Capacity would require a capacity facotr phi, which for plain concrete would be 0.6 I would think. so 0.6*0.36*sqrt(0.36) - which would lower the chance of having only 1 layer of reinforcement quite dramatically
  3. li0ngalahad

    AS3600 cl 11.2.1 vs 11.7.3 - Two Layers fo reinforcement in walls

    Hi everyone I would like to bring to everyone's attention these two apparently contradictory clauses from AS3600. Clause 11.2.1 says Braced walls where in-plane horizontal forces, acting in conjunction with the axial forces, are such that where a horizontal cross-section of the wall [...] (b)...
  4. li0ngalahad

    AS 3600 Cl 10.8 Transmission of Axial Force through floor systems

    @Rav01 I see a few issues in your k-value calculation. 1. you apply a stiffness reduction to the column. However, these are intended for lateral resisting elements (so they should be applied when analyzing lateral loads, not gravity loads), and it's unconservative for the k-value calculation to...
  5. li0ngalahad

    Warrning message - "No usable starting vectors are available; no ritz modes can be found"

    probably you have some instabilities in your model (ill-conditions), unlike Eigen, Ritz most of the times will not run if there's an instability.
  6. li0ngalahad

    Zero Interstory drift for story 1 - Etabs

    There is no reason for a storey to have zero drift other than some errors in the calculation. Unlike diaphgram drifts, storey drifts should be calculated independent from drift assignemnt and should never be zero. I'd suggest you to import the $et file and re-run the model
  7. li0ngalahad

    AS1170.4 Draft

    Actually, sometime ago I took some interest in this matter and created a little tool that plotted all the raw data on a map (actual towns only), you can hover on it and see all the different values for each location, for whoever interested you can find it attached here (download and open with...
  8. li0ngalahad

    AS1170.4 Draft

    I don't think that's correct. That's a 10% probability in 50 years, which is actually a 475y return period. 500y return period will be roughly 1.05 times that, so 0.033 See below the 2018 map That's quite concerning actually, it goes to show how these assessments can be relied upon only to...
  9. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    I know, but I'm not going take a forum comment itself as a reliable source and consider it the official position of the committee. I don't know, the idea that I can have basically a whole core with boundary elements only around doors doesn't sit too well with me. But maybe it's just me...
  10. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    Yes I know that thread, I even commented on it :-) however I dont see any references to the claim that a discontinuous edge is only at free ends and doors, just some other people saying what is their understanding. Generally speaking, I believe geometric discontinuities are not limited to a...
  11. li0ngalahad

    AS1170.4 Draft

    My understanding is that the logic of using such high Z values compared to the actual, newly calculated values, is the dramatic increase in acceleration on 2500y return period earthquake typical of low seismicity zones, so if we designed at 500y for the real Z value, that one time in history...
  12. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    mmmh...the more I look into this the less I am convinced this is right I have found few instances where the definition of "end zones" and "boundary regions" is applied to compound walls corners and wall instersections. For example...
  13. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    JSN, glad it seems we are more or less on the same page on this Yes but doing so we are saying boundary elements should be detailed at all walls and at all levels, all the way up to roof - it seems a bit excessive. Maybe it could be avoided for the levels where cracking does not occour with...
  14. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    Yeah, exactly. Also, looking at other codes (EC, NZS) the neutral axis depth considered when determining the boundary element region is generally calculated at ultimate limit state, never for the "uncracked" gross section. I believe the reason for the code indicating the use for the gross...
  15. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    The neutral axis depth calculation is based on linear-elastic cracked analysis Which part would not prevent the use of the cracked section? Is it the "gross cross section" part? If we do that and use the "uncracked" section then the neutral axis will always sit in the middle of the wall, which...
  16. li0ngalahad

    AS3600 Boundary elements in moderately ductile shear walls

    I gave this thing some thoughts in the past days, and I think I may have come up with a solution to this that make some sense (at least it does to me) For limited ductile walls, check any region of the wall exceeding 0.15 f'c (based on mu=2 and Sp=0.77) and restain the vertical reinforcement in...
  17. li0ngalahad

    AS1170.4 Draft

    for sure. However the map shows that little square indicating Perth clearly outside of the 0.09 zone, which it's funny at the very least. Also I wonder if "Perth" includes the whole metropolitan area? Could we design a structure in, say, Fremantle or Rockingham, with Z=0.08?
  18. li0ngalahad

    AS1170.4 Draft

    I think the map is quite clear and the table makes it even more clear. There is no interpolation. All zones within a contour boundary have the Z value shown on the boundary, unless they are included in an inner contour with a higher Z value. That's it. Adding the 0.08 point simply says, this...
  19. li0ngalahad

    AS1170.4 Draft

    The contour map is the same, with the addition of the Z=0.08 points, as per some of the comments above
  20. li0ngalahad

    Concrete Column Transitions - Bearing Area

    Taking A1 as the overlapping area and A2 at mid depth of the transition element (slab, beam or drop cap) is also what I do and I believe it's the right approach The key is that A2 must be "geometrically similar" (same shape and aspect ratio) and concentric to A1. In this situation, for...

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