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  1. BAretired

    Truss Top Chord Lateral Support

    Yes, I believe so. Connection should be a moment connection to laterally support the top chord. Hell no! That would be a pin joint. You need to prevent rotation of the verticals. I think you need to develop your basic concept first before going into these details.
  2. BAretired

    Beam Reinforcement Calculation

    Great! We have total agreement. Thanks human909.
  3. BAretired

    Cantilever Plate bending with UDL

    Line load perpendicular to fixed edge. 45 degrees looks okay to me.
  4. BAretired

    Beam Reinforcement Calculation

    My understanding for the weld calculation below is to find the Q value for the upper or lower green shape. The upper fillet welds must resist a shear flow of VQ/I where Q is taken for the upper green outline. Similarly, the lower welds resist VQ/I where Q is for the lower green outline.
  5. BAretired

    Truss Top Chord Lateral Support

    Sounds about right. There may be constructability issues. a) You probably won't have tapered sloping poles like these, do you? b) Black, cranked tapered, decorative poles (non structural). c) Looks like the blue supports fit into the black cranked tapered poles? d) I will not comment on...
  6. BAretired

    Beam Reinforcement Calculation

    Thanks HTURKAK, I see it now. Very neat! Once again, I apologize to everyone for prolonging this discussion to so many posts. I will try to keep quiet on this subject from here on.
  7. BAretired

    Beam Reinforcement Calculation

    Problem 543. It's the yellow area. Maybe someone can get it right.
  8. BAretired

    Beam Reinforcement Calculation

    Thanks RWW0002, You are probably correct. I am still struggling with it, but I have spent far too much time on it already. I may take another look at it when the fog clears from my brain. I tried to solve Problem 543. in "Elements of Strength of Materials" by Timoshenko and McCullough...
  9. BAretired

    Beam Reinforcement Calculation

    Guilty as charged...I apologize for my unprofessional remarks.
  10. BAretired

    Beam Reinforcement Calculation

    Just above the welds, the horizontal shear is in the beam web, not the side plates. Just below the welds, shear is shared by the side plates, although there could be a bit of shear lag, so the shear stress needs to build up. I agree that Q above the welds is unchanged by the presence of side...
  11. BAretired

    Truss Top Chord Lateral Support

    No need, it was not clearly written and is not really important. In structures, there is usually more than one way to do the job. I cannot tell from the photograph precisely how the members came together. Do it your way. Then you can say, like Frank Sinatra, "I did it my way".
  12. BAretired

    Beam Reinforcement Calculation

    Horizontal shear in the web and side plates must be resisted by welds top and bottom of side plates. The value of Q is shown below in two places, at the top of plates and at the neutral axis. Horizontal shear stress is VQ/It where t is the material thickness at the position under...
  13. BAretired

    Beam Reinforcement Calculation

    VQ/I is zero at the top of the cross section, but not at the top and bottom of the plates.
  14. BAretired

    Beam Reinforcement Calculation

    When you want to find horizontal shear, the formula which you have quoted is correct, but dA refers to the area above the level you are examining, not the total area. If you are talking about the link to the 2020 thread, I don't think I participated in it at the time. I have scanned it...
  15. BAretired

    Beam Reinforcement Calculation

    But d does not equal 0. Look at my diagram. Q at 0 (neutral axis) = 3*1.5 + 2*1 = 6.5 where 3 is the red area above the neutral axis and 1.5 is the distance from its centroid to the N.A. and 2 is the area of the two blue plates above the N.A. and 1 is the distance from the centroid to the N.A...
  16. BAretired

    Beam Reinforcement Calculation

    Shear flow BETWEEN plates and beam is not defined. The plates are welded to the web of the beam. We need to think of the red and blue plates on my sketch as a composite unit. We care about the strength of weld required to generate the shear flow in the blue plates (which is not zero). I...
  17. BAretired

    Beam Reinforcement Calculation

    I'm not sure how that relates to this thread, but I will think about it.
  18. BAretired

    Beam Reinforcement Calculation

    Yes there is. My/I is not correct for stress in the plastic range. Here are a few 'q' values for your amusement. Note that q at y=2 is unchanged by the presence of side plates. The explanation is that moment of inertia is the wrong property to use in the plastic or partial plastic range.
  19. BAretired

    Beam Reinforcement Calculation

    You are wrong. There is shear flow for every beam, even a simple rectangular beam. Again, you are bloody wrong! It is a geometric property which is used in the elastic range, not the plastic range. Q is not 0 for a beam with side plates. In fact, it is not 0 for any beam. It is exact...
  20. BAretired

    Truss Top Chord Lateral Support

    You could do that if you wish. The bridge in the photo couldn't do that because of the bent pole projecting up where you show the railing. Personally, I like the red member because it makes the support easier to erect, although it still has to be supported to prevent it from falling over. I...

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