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  • Users: Pawel27
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  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

    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...
  3. 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...
  4. 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...
  5. Pawel27

    ASCE 7-10

    I would like to use combination in section C2.3.5 i.e. 1.2D+1.6L+1.0T. I do not know what resistance factor for design strength should be used. I have spatial stress state (not only tension, compression, shear separately). What value should be multiplied Nominal Strength to get Design Strength?
  6. Pawel27

    General considerations of seismic model

    Hello everobydoy, I would like to ask for general approach to structure supported by columns (see attachment). I want to do simple static analysis by using known acceleration at different levels. For sure action at column base must be also considered. How to include ground motion in such model...
  7. Pawel27

    Thermal stress in fin (boiler wall)

    I would like to discuss about thermal stress in the fin of the boiler wall. Along fin width there is temperature distribution more or less like on picture "temp_distribution.jpg". Some fin has bigger elongation and some smaller one. There will be something like shear. For our considerations we...
  8. Pawel27

    Limit load analysis - ASME 2010

    I would like to ask about Limit-load analysis method (ASME 2010 sec. III, div.2, 5.2.2). This method is one of Plastic Collapse Protection. At this plastic collapse load plastic region appears. This is not yet ultimate load, but something before ultimate strength. In 5.2.3.4 There are...
  9. Pawel27

    Silo load

    I have structure filled wit ash like in attachment. I am considering silo load from this ash. Unfortunately all books, codes, publications doesn't consider structure like this. There is only vertical wall and hopper below. In my structure there is also next vertical wall (called by me "2nd...
  10. Pawel27

    Equivalent thickness for orthotropic plate

    I am looking for method to get plate with constant thickness which is equivalent to orthotropic plate. It concerns different loadings - tension/compression and bending are not the problem. The problem is when there is combined load like tension+bending. I would like to get formula in both...
  11. Pawel27

    ASME sect. VIII division 2 - thermal gradient

    Have a look at Stress categorization method in ASME. I am thinking about thermal gradient across header wall thickness. I know opinion that this thermal gradient is important only in fatigue phenomena. In my opinion it can be in Q classification. If it is necessary we can assume in consideratin...
  12. Pawel27

    Structural strain extrapolation in nozzle-header connection

    In EN 13445-3, B.7.6, there is quadratic extrapolation described. This extrapolation is used to get structural strain. The problem is that I get bigger value of strain using extrapolation than don't use it. Have anyone experience with this extrapolation function. Similar problem was described...
  13. Pawel27

    EN 1993-1-9

    In EN 1993-1-9 there is factor gammaFf (see attachment). I cannot find what value should be used. I have got one general publications where 1.5 is used. I cannot find any recommendation in Eurocode.
  14. Pawel27

    Low cycle fatigue

    I am looking for Eurocode where low cycle fatigue is described. I have found only PN-EN 1993-1-9, but there are fatigue curves from 10^4 cycles. I guess this is not described yet.
  15. Pawel27

    Damage equivalent factor - EN 1993-1-9

    Hello! I have problem with finding damage equivalent factor, mentioned in section 6.2 of EN 1993-1-9. Any reference will be appreciated.
  16. Pawel27

    Gross Plastic Deformation - too conservative or not

    I would like to ask Gross Plastic Deformation users about their experience with this method. From my observation this method can be too conservative. When I consider header nozzle connection in Autopipe model results are satisfactory. Meanwhile in 3D FEM model with GPD, results are not...
  17. Pawel27

    Structural stress vs total stress

    I am considering what is the difference between "Structural stress" and "total stress". Short explanation will be appreciated.
  18. Pawel27

    Stress averaging between different shell thickness

    Once I met the statement that in case of transition between shells with different thickness, stress averaging by postprocessor is not allowed. Good example is header-nozzle connection. Please explain what is the reason of it.
  19. Pawel27

    ASME plastic coupled analysis

    Dear all, I have problem with ASME coupled analysis. I have one structure for which I performed coupled thermal-mechanical analysis (acc. to ASME, section VIII, Div 2, article 4-1). There can be used linear analysis. Everything seems to be clear for me. Unfortunately I have another one...
  20. Pawel27

    Yield limit with plastic strain correlation

    I often use perfectly plastic material model in FEM analysis. I have noticed where stress are above yield limit, there is often no plastic strain. Plastic strain appears in the area where stress are much more above yield limit. Any comments and hints about this material model behaviour will be...

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