Jummybear

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About Jummybear

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  • Birthday 02/02/84

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    TLN
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    Civil Engineer
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    Actions on Structures
  1. It was second one
  2. Yes, you are right. Participation of mass is low. See picture attached. Did you get twisting mode as first one?
  3. Dear all, I am working now on a 30 floor tall building. I run a modal analysis and get 1 mode or 1 and 2 mode as a buckling of local element - r/c wall, which is a part of rigidy core. Usually I get first 2 forms for the whole building in Y or X direction and third one is twisting one. First time I get local buckling in first modes. Should I fix it or I can ignore it? Your suggestions? I am not fimilar with tall building and fortunately this building is not my project for designing, but its a good opportunity to gain some experience in calculating such buildings.
  4. One more question: I am not fimilar with calculation of cscd. My calculated value for 20m aluminium mast is about 1,27. Is it real? In EC graph-s cscd factor varies from 0.9 to 1.1...
  5. No need to post new topic, so I will ask here. I am designing a mast for telecommunication use. I should use cscd structural factor in my case. Question about antennas and other equipment on mast: should I use cscd factor calculating wind load on them?
  6. Hi, I have some misunderstanding with this Reynolds number. The formula is very simple, EC 1991-1-4 p.7.9.1 Re=b*vm(ze)/v. Cant figure out how exactly should I calculate vm(ze). It is said that " Vm(Ze) is the peak wind velocity defined in Note 2 of Figure 7.27at height Z" In Note 2 said: " Typical values in the above Figure are shown in Table 7.12. Figure and Table are based on the Reynolds number with v=sqrt(2qp/ro) and qp given in 4.5" But I cant get reasonable wind speed according this formula... I am doing a mistake somewhere? PS Topic solved. As usual, the reason was very simple: I forgot to convert units from kN/m2 to N/m2
  7. Hi engineers, There are tabulated data in "EC 1992-1-2 General rules. Structural fire design" for columns, but only for braced ones. What about unbraced ones? Any suggestions?
  8. Hi all, can smb help me with snow loads in spain, what are the country regulations?
  9. Looks like I have found an example in one timber book and also found a mistake.
  10. Can somebody share an example of these calculation? Its quite simple, the details are in EC 1995-1-1 Annex B. I am trying to make a simple spreadsheet in excel for checking mechanically connected beams. Looks like I have a mistake somewhere because my results looks strange but I cant find it.. Probably there is some example in some literature or paper, but I steel didnt find it. Thanks in advice.
  11. Maybe you are right. In my point of view there are different stress states possible with discrete supports. But EC5 doesn't provide more detailed explanations how to take these different cases into account. Its just wrote that for members on discrete supports provided that l1>=2h the value of kc,90 should be taken as 1,5 for solid softwood timber. And thats all. I have added one sketch for explanation what I mean. Anyway, thank you for help. Drawing2 Model (3).pdf
  12. Then how it be ok by your calculation if with compression strength of 0,25kN/cm2 and y=1,3 and kmod=0,8 we get max perm force of (0,25*0,8/1,3)*(13,5+3+3)*19,5=58,5kN<83kN with kc,90=1.0. If I use kc,90=1.5 then we get 58.5*1.5=87.75kN>83kN. Capacity ratio is only 87.7/83=1.06...
  13. Capacity Thank you for reply. kc,90 is also an issue. In truss calculation it was 1,5. I would use 1,25 or even 1,0 to be on a safe side. Its only 1 such joint in whole frame house, others with much smaller loads (about 10-15kN per truss support point). What compression strength do you use in your calculations? I know that 3 studs is enough but I am not sure that truss will much exactly the same place with studs, some deviation is possible on site so 1 stud is just additional to have a bit more area if truss will move a little bit. One additional question: if you use steel plates for "reinforcing" the joint, whats the thickness of it?
  14. Hi everyone. I get different numbers for fc,90,k varying from 2,5 to 7 Mpa. In handbook for our country I get 5,5 Mpa and in some calculation examples for EC5 the smallest number was 2,5 Mpa. Another problem is l,eff calculation of compression length (compression area). I have a wood truss supported by frame wall. Truss calculation is made by other designer, my task is a wall. I can vary a number of stud, placement and so on. The problem is that capacity depending on which compression strength i take in calculation and which area. In truss calculation it is said that min support length should be 170mm and in this case compression strength is enough. Maybe I am a bit conservative, but I get barely ration of ~1,0 or even less. Any ideas? Advises? What is a possible solutions for reinforcing such place (steel plate for load distribution on larger area or something else)? Small sketch is attached. Thank you in advice! Drawing2 Model (1).pdf PS We use wood of strength class C24
  15. Overall coef for designing whole structure, foundations, columns etc. Local coefficients for local elements like side roof panels, fastenings and so on