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  1. hocho

    Virtual vs Real Neutral Axis

    BA.. thank you so much for all the help and enlightening tips on the theoretical side. I couldn't have understood some concept for many months without you. Appreciate it so much. I guess I now have to ask all local contractors about grinding and polishing. Beers and cheers to you :)
  2. hocho

    Virtual vs Real Neutral Axis

    Ok. But with the simple beam and column sample hit with lateral force USB97. The one with additional 5kN uniform load in the top beam has lower ground floor column seismic moment. See: Without the additional 5kN uniform load in top beam, there is greater ground seismic column moment. See...
  3. hocho

    Virtual vs Real Neutral Axis

    So those moments already take into account the deformation as one of the superpositions. Makes good sense. How many structural engineers intentionally makes the second floor having more load to kinda decrease the moments in the columns in ground floor? Have you done it? Between the topping and...
  4. hocho

    Virtual vs Real Neutral Axis

    Hi Ba.. i'm a bit confused by your drawing Is the curved lines supposed to show the moments? Why are they showing it pinned? What would happen if you draw it double curvature in one beam that is originaly depicted in etabs (I'm referring to the simple beam column span sample. not the complex...
  5. hocho

    Virtual vs Real Neutral Axis

    Ok. We'll first put the roofing before deciding whether to remove the waterproof topping (the reason for the topping was to let rain flow to drain). Btw.. you were wondering yesterday in the message "Why does C1 have a large moment at Story 3 (-22.17 or -20.88kN-m), C2 has less than half as...
  6. hocho

    Virtual vs Real Neutral Axis

    Gee. Thanks. I couldn't have figured this out myself for many months. It's like the concept of superposition, isn't it. In superposition, there is really cancellation effect. Can't you say the decrease is due to some cancellation. So more load in the 2nd floor top can lessen the moments in the...
  7. hocho

    Virtual vs Real Neutral Axis

    Let's just create a very simple beam span supported by 2 columns. The 3D of it is the following: The following shows the beam and column moments. In the following. Uniform load of 5 kN were added to the top beam. You can see that the moments of the lower columns decrease.. I simply want to...
  8. hocho

    Virtual vs Real Neutral Axis

    The contractor wants to follow the original plan where the sides of the rafter rested on the perimeter beam. I asked the designer if I can rest the rafter sides at columns instead. Designer said I can do either because it's just light roofting anyway and depends on the skill of the contractor...
  9. hocho

    Virtual vs Real Neutral Axis

    Tomorrow we will spend about 5 hours to bring it up because they are so heavy. W8x21 is 21 lbs per foot.. so per piece (21 x 20 feet)is about 420 lbs.. can't be carried by even 3 people. They need to pulley chain it up. 420 lbs is about 1.868253072 Kilonewton. So 1 complete rafters composing of...
  10. hocho

    Virtual vs Real Neutral Axis

    BA. On Monday next week (4 days from now).. we'll start to add the roof designed by the same designer company to cover the third floor. Again he doesn't want to think about epoxy being soft modulus and say the building was originally designed for 4 storey with concrete roof so all forces are...
  11. hocho

    Virtual vs Real Neutral Axis

    You got my point but my other point is there is moment cancel (edit: not complete moment cancel but moment lessening effect on lower column) or restrain effect in every normal building at edge columnw right? To post my edit above with additional comments. Here is what i said Here are clearer...
  12. hocho

    Virtual vs Real Neutral Axis

    Im referring to column above the storey. It can affect the moment in the lower storey right below it right? For example you have 10kN-m at top of a storey. If you can pull or push by hydraulic the column above the joint in the next higher storey. You can change the moment in the joint and hence...
  13. hocho

    Virtual vs Real Neutral Axis

    Oh its just showing the middle elevation longitudinally. Right now in actual bldg C6 is only up to 3rd floor without any roof yet. So column has zero moment at top. In C1 or the middle. I didnt delete the beams on its transverse side and longitudinal rear. Note the building was designed for 4...
  14. hocho

    Virtual vs Real Neutral Axis

    That output is not meant to accurately depict the exact structural framing and loading because it is the designer who is good in that especially seismic. I'm asking just how opposite moments seem to interact. And I showed it to you pinned bases because I thought most are more familiar with...
  15. hocho

    Virtual vs Real Neutral Axis

    That's just a more extreme example (omitting entire column and beam in the analysis). Initially I have reduced the load in the second floor top and there is an increase in the column moment at ground floor. For example.. this is the dead load loading of my structure (dead load of slabs connected...
  16. hocho

    Virtual vs Real Neutral Axis

    BA.. I'd not dig thru slab and remove the sleeve as it seems fixed and it's not possible with tenant on top of it. So I planned to just remove the waterproof topping above second floor where a roof will be put to lessen the load opposite the epoxy void to avoid compression in the lower S shape...
  17. hocho

    Virtual vs Real Neutral Axis

    What is the resultant then of this epoxy compressive block? In the concrete one, the resultant is the average of the concrete compressive block (the C).. or you mean one must not even use resultant in the epoxy block? Or how to compute for it.. how do you handle this say the stress variation in...
  18. hocho

    Virtual vs Real Neutral Axis

    Size----------------- d - - - b - - - t - - - - Area - - W- - - Ix- - - Iy- - Wx- - Wy W 14 x 22 ----13.74 --- 5 ------ 0.230 -- 6.49 -- 22 -- 199 -- 7 -- 29.0 -- 2.8 W 10 x 45 ---10.10 -- 8.020 -- 0.350 -- 13.3 -- 45 -- 248 -- 53.4 -- 49.1 -- 13.3 In the above example. The shorter w10x45...
  19. hocho

    Virtual vs Real Neutral Axis

    Ok. For years I always just wanted to focus on concrete structures and not steel structures to avoid more understanding and spending time studying it. But this epoxy repair in void is finally making me think of steel especially when you said the bars in compression can act like steel. After...
  20. hocho

    Virtual vs Real Neutral Axis

    Ok. Thanks for all assistance. To summarize and for my conclusion of it all after 2 years of trying to understand the behavior of epoxy repair in column voids. Instead of the designed 4 storey with concrete roof and all concrete walls. We would just make it 3 storey with very light roof and...

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