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WR1

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Everything posted by WR1

  1. WR1
    yes, you have to calculate the net tensile strain in extreme layer. Approx it will be somewhere near to 0.02
  2. WR1
    Batoul what you did in mass source is perfectly okay but you dont have any sdl or live load applied in model. so recheck. rest i have told you that the base shear is same in both directions if you check from tables. dont worry too much abt it.
  3. WR1
    why make your lift difficult like used to be in etabs 9 to define load cases different for each direction. in etabs 2013 you can just define one load case for E and one W and include all directions x y plus minus in just one case. just tick all 6 check boxes. in mass source you will include 100% dead load plus 100% mech load in this building if any.
  4. WR1
    I dont know if you are producing results from a different model than what you have posted here. I am getting the same results again and again in both directions. for example see the attached image. there is now live or sdl load applied in the model although included in mass source. also there are some warning while running the analysis. you dont need to make separate load cases for different directions in etabs. you can do all in just one load case.
  5. WR1
    no need to draw it as special inverted beam, just draw it as normal line. you can save as your model and then delete the slabs just to design the inverted beams but put loading on beams from slabs manually as line loads. this way you are not taking t section in stiffness calculations that is conservative. just put the reinforcement that you get from etabs and design shear stirrups manually for additional tension. this is T=Asfy Phi (Phi is 0.9) for example calculate the slab loading including self weight per meter on this beam for example lets say ultimate load on 1.2D+1.6L = 50kn/m (just an assumption) then 50 * 1000 N/m = As (mm²/m) . 420 (N/mm²) . 0.9 As = 132 mm²/m . now check how many stirrup legs you have provided per meter. for example (dia 10 4 legs every 200mm) that means you have 5*4=20 legs per meter 20 x 78.5 = 1570 mm² / 1m run of beam
  6. WR1
    also see this http://www.sepakistan.com/topic/109-building-drifts-in-etabs/
  7. WR1
    what exactly is your question for the model you attached?
  8. WR1
    1. its simple. just study about t and rectangular sections. where you design for T section and where you design as rectangular section for drop beams? for inverted beams just flip these sections and design according to that. another thing to make sure is to design inverted beam shear stress so that they are capable to carry the axial tension. 2. important question. meshing in slab or wall or in anything is very important thing in FEA. just read in any finite element book about meshing. it depends on the problem . some times you need refined mesh some times not. google mesh convergence topic. make an example of point load on slab and keep refining mesh at that area and notice the values of stress. does that keep increasing with refined mesh? then ask your self why? and what is the best mesh size that gives accurate results? then study about stress concentration in any good fea book. 3. continue the beam atleast to two mesh points inside the wall. 4. yes!
  9. WR1
    period and base shear should be same in any way you view them in any software. where is the plot of story shear? did u attach it here?
  10. WR1
    welcome to the forum, ask other students to join us too
  11. WR1
    unfortunately im not any more on facebook, its been more than 8 months now . dont worry i will come back to promote my stuff too
  12. WR1
    w is the circular frequency or angular velocity in units of rad/s f is cyclic frequency or cycles per second in units of Hz they relate to each other by w = 2 Pi f for example steady state response of a structure under load is F(t) = Fsin (wt+theta)
  13. WR1
    this was the table i was talking about i forgot to attach.
  14. WR1
    If you see tables of seismic calculations, you will notice period is 1s in each direction. Also story shear is same in x and y direction. Find the attached image of table. base shear in EQ1x and EQ1y is same. also base in x and y directions of EQ2 is same. but EQ1 and EQ2 are different from each other because of difference in story range. You can check this in tables of your model.
  15. WR1
    they are almost same. i will check it tomorrow in etabs 2013
  16. WR1
    I dont have etabs 2013 so cannot open your model. how you are checking the story shear? by tables? upload a screenshot of seismic load cases data in both x and y directions here
  17. WR1
    story shear along x and y direction might be different if you are performing dynamic analysis and the building has different stiffness in different directions. are you performing static or dynamic analysis? deflection in z is so large? how much large? is it like 50km? or just more than L/480? if its in km then support your nodes and check the model again. if its the second case, then stiffen the plates, beams, reduce loads etc. period of mode is very high. again how much? if its like 20 seconds then support the nodes. one way to check is check deformed shape. if building is not deforming at all it means they are some nodes not properly modeled or connected. if T is more than 1s then the building is very flexible. what is the total height of building? stiffen the building by adding shear walls etc
  18. WR1
    I am not sure exactly but I have found that MAT options gives more bearing pressure and I always use MAT for strip and rafts. I consider FOOTING for modelling purposes in SAFE only for isolated or 2 combined column footing only.
  19. WR1
    Middle strip, column strip is for manual design. You can use the same in SAFE. But you can also draw unit width strips in x and y directions irrespective of column locations and put reinforcement according to that. At the end FE results from SAFE show you stress results and you have to satisfy that with reinforcement. Its not compulsory to draw strips as just column and middle strips. In SAFE a design strip can be of any width, usually 1m/1ft wide
  20. WR1
    I am not sure about 5h provision in SAFE. I will check. Thank a lot!
  21. WR1
    lol! yes I am and I am very eager to launch it this month. I converted my idea of writing a modelling book to video book and then to courses
  22. WR1
    If you really want to go in details, then see RISA explanation what it does in finding critical parameter; https://risa.com/risahelp/risafoundation/Content/Common_Design/Punching%20Shear%20-%20Design.htm Goto " Finding the Controlling Case (Interior, Edge or Corner) " section and see how many options are there to find punching perimeter; you can do this manually if the column is very critical.
  23. WR1
    And before that, make sure the document is really from ACI? (I also dont know about this clause, so please let me know, I am learning from you). Because the document you are referring says "ADAPT Technical Notes", its does not look like official document of ACI. And remember ADAPT program is used for PT slabs. ( I mentioned this in post#14 as well). Also you still have the option to overwrite punching perimeter (as he said in post#7). Show me the edge column definition from some standard ACI paper or code in next post. (Not from the documents you have already mentioned). Thanks.
  24. WR1
    The document section I have quoted clearly says the clause you were mentioning is for prestressed sections. Now you have attached the summary that explains the intent of the document that the clauses in this document are written for the design of prestressed and non-prestressed concrete sections (same like ACI). Based on this you cannot say that all what is written inside is applicable to both. Each one of them is treated separately. The section I quoted above is for "Prestressed". Instead of putting links and reference to other items, why don't you show me directly where it is written in ACI the definition of edge column with distance less than d/2? So that we can talk directly on the specific point instead of loop referencing! I have not read the documents you attached the link for, in your last post. Please take a screenshot where it says specifically, and attach it here.
  25. WR1
    Moreover, SAFE methods are based on Amin Ghalis book for deflection and punching. You can read his book for insight. (Author of this technical article as well)
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