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Recent content by Pawel27

  1. Pawel27

    EN 1993-1-9 low cycle fatigue verification

    Dear All, I have question to section 8 of EN 1993-1-9. There is condition for stress range not to exceed 1,5fy and 1,5fy/(3)^0,5 (direct and shear stress respectively). Some times ago I read that if this condition is fullfilled then low cycle fatigue will not occur. I don't rememeber where I...
  2. Pawel27

    Wind action at duct bend

    It is 78 inches.
  3. Pawel27

    Wind action at duct bend

    I am interested in how to apply wind action at duct bend (see green colour in attachment). In case of straight duct line I use "Pressure distribution of circular cylinders" according to EN 1991-1-4 from section 7.9. You can see also this pressure distribution in attachment (section A-A). I do...
  4. Pawel27

    Mass hanging - equilibrium equations using rod length

    Yes, gravity center is usually misaligned (not central to the supporting rods). I just try to write down relations (equations) to describe such kind of structures looking at VBA code.
  5. Pawel27

    Mass hanging - equilibrium equations using rod length

    Rb1957 - looking at matrix methods it seems to be Direct Stiffness method used, but I am not sure yet. I must look at it more precisely. There is tension rod stiffness EA/L used like in VBA.
  6. Pawel27

    Mass hanging - equilibrium equations using rod length

    Handleman, Greg, IDS we can assume that this is a stiff box suspended into rods. When I showed VBA code maybe it will be better to look at it as a 3-D problem. Rb1957 - I also tried to relate it with known equation sigma=FL/EA, but looking at units at both sides of equation F11 seems to be a...
  7. Pawel27

    Mass hanging - equilibrium equations using rod length

    Wires (rods) are vertically oriented (red colour). Suspended element is a rectangle (black colour). The pictures above are 2-D simplification. In reality it is 3-d problem with many rods. Below is 3-d sketch - maybe now it will be more clear. If You have any questions don't hesitate to ask...
  8. Pawel27

    Mass hanging - equilibrium equations using rod length

    Some description more: Trying describe F11, F12 and F13 generally, it looks like below: F11: M*L/EA = x1^2+x2^2+x3^2... ; M is instead of F11. F11 seems to be Moment. F12: M*L/EA = x1y1+x2y2+x3y3... ; M is instead of F12. F12 seems to be Moment. F13: F*L/EA = x ; F...
  9. Pawel27

    Mass hanging - equilibrium equations using rod length

    I must change picture when we consider code above.http://files.engineering.com/getfile.aspx?folder=dc7d25b2-4142-43e2-a918-fb7cd432ce1f&file=Mass_hanging_rev_0.png
  10. Pawel27

    Mass hanging - equilibrium equations using rod length

    Hangleman - it can be something in this direction You described. Rb1957 - it is 3-dimensional subject. There is no vibration or other dynamic interactions. There are many rods about 20, 30, 40 rods - it depends from the element. These are boiler Power Station suspended elements. It is very...
  11. Pawel27

    Mass hanging - equilibrium equations using rod length

    No, it is not this solution. This is much more complicated. When I have more time I will try to prepare something more.
  12. Pawel27

    Mass hanging - equilibrium equations using rod length

    I am looking for equation describing situation like on the picture. It should be equilibrium equation using Rod Length and Rod Young modulus and concerns gravity center. The problem is that I have ready quite long Visual Basic code made by other author but I cannot understand it. Let's start my...
  13. Pawel27

    Creeping in seismic load

    I calculate seismic guide of the structure. This guide is in high temperature, i.e. in creeping area. Lets assume that creep strength (1%) is 100MPa. During normal work, stress are below this 100MPa value. When seismic appears I have some stress concentration above creep strength. The question...
  14. Pawel27

    ASCE 7-10

    One more remark: I think about using 95% of yield stress according to section 5.1.2 as allowable stress in ASD method(see attachment above).
  15. Pawel27

    ASCE 7-10

    I got ANSI/AISC 360-05 Specification for Structural Steel Buildings. I didn't find answer what is allowable stress. OK, maybe auxiliary question, which help focus on the point of subject: In attachment there is a screenshot from book "The structural design of air ducts and gas ducts" (5.1.1...
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