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Everything posted by Rana

  1. Calculate T in ETABS

    Who said so? For majority of the buildings (low rise) dynamic time period is way lesser than 1.4Ta. Read code to understand about these limits. It should have been; if Tmode>1.4Ta then T=1.4Ta. Just a typo mistake i think, but inside ETABS it takes it correctly for both UBC and IBC/ASCE codes. Don't worry.
  2. moment of inertia in shear walls

    pretty simple check stresses in walls, if they are more than modulus of rupture they are cracked, use 0.35 otherwise they are un-cracked so use 0.7. Then iterate. Cracked walls will be in high rise with more seismic loads. See above.
  3. Temperature Loading on walls.

    What are the restraints to circular walls? Is it open from top? The circular shape is it self restraining (hoop stresses). Outward and inward? Yes, if bowing action but you need to apply gradient temperature then in softwares. Sign will determine if it bows outwards or inwards. Which software you are talking about? Yes application of any load in any software and even in papers depends on the direction in which you want to apply. Yes 1.2 factor for T, but not all combinations. You need to find out logically where you will need to use 1.2T. I mean effects should not be counteracting.
  4. Cost per square feet

    I can connect you with some on this if you like...
  5. Raft Modeling In Etabs

    Make one and post for us please!
  6. Shear wall design

    How do I know what is your confusion without you writing it down for me?
  7. Bearing Capacity

    I dont think code dictates that but yes common sense sure does. I wouldnt design foundation unless from some source I have the bearing capacity information. Even if it is preliminary design and you put a note that "the foundations have been designed assuming.....capacity", you should do some research of nearyby buildings. You cant just guess, i think.
  8. Required force method

    First off, is your Limcon cracked or purchases? If cracked, there are certain variables in the software that are "FIXED". They do not change if you change values. So beware!
  9. raft punching

    Depends if the sheet is correct? Does the sheet take into account moments?
  10. Structural Systems according to UBC-97

    Really? Moment frame type has nothing to do with location except some limitations in codes. Can't you have special moment frame in Zone 2? Yes, you can! Type depends on the ductility and framing of building system. Do you think it has enough ductility? If yes then it could be special even in Zone 0. But obviously it will cost more to provide that ductility and detailing for zone 0. But generally speaking, you could design special frames in zone 2B or ordinary in higher zones, depends on the framing.
  11. Assigning Of Temperature Load In Etabs And Safe

    not true in all cases. uncontrolled internal temperature has the same effects like outside sun heat on the structure. There are usually documents stating weather station data. You should use mean yearly average highs and lows not daily. It also depends on approval authority. For example in Dubai, limit is 45m. Expansion joints are nice from structural point of view only. As a structural engineer, Id try my best to avoid them. Construction isnt that easy for expansion joints. What about water leakage? Except ground floor columns and walls that will have huge forces due to restrain (supports). This is my opinion. I don't think T+E should be added.
  12. Bearing Capacity

    Known or unknow?
  13. Basic question about rebars selection

    Yes, more bars less dia is better. Also check what is commercialy viable. There is commercial as well as health & safety aspect to it as well. For example using less bars of dia 40 reduce congestion and easy handling and placing but is it safe for workers to carry such huge bar? Accidents?
  14. design Floor Slab in Grade

    You could also use concrete society report no. 34 for plastic design of industry ground slabs.
  15. Good point again. In such cases, you have to deal with the notorious huge nerve sapping temperature forces.
  16. Column Design In Etabs

    You are not getting the point. Have you referred to the codes? Aci or bs or whatever? An interior column with huge axial load multiplied by minimum e can produce huge moment even if the original moment from frame is 0.

    2d analysis is never recommended with walls above. https://wiki.csiamerica.com/m/view-rendered-page.action?spaceKey=safe&title=Modeling+uplift+and+foundations+on+soil+supports
  18. Slab deflection in ETABS

    Hey man, hold on. Your building isnt symmetrical. Also the theres difference between axial stiffness of cols vs walls. This will effect z direction deflections from bottom to top stories. 2nd thing..safe..in safe deflections will be different than in etabs. This has been discussed no of times here and you can search.
  19. Slab deflection in ETABS

    If the building is regular as you said with same column sizes, axial shortening should be same provided loading and gemoetry all are same and symmetrical. Gravity deflection on same combination should be same at each level. And by deflection i mean z deflection not x.
  20. Thickness of footing

    10 under the root factored load in kN is the thickness required in mm (tried & tested here).
  21. Reduce lateral displacement

    Decrease the distance between CR & CM. It will not eliminate 100% due to inherent torsion.
  22. Signup with IStructE and start your road toward chartership.
  23. Effective width of Point Load

    In addition to above, to get an idea how point load is distributed, see PCI Handbook.
  24. B/C ratio output in Etabs

    Answer is simple. Top columns have less axial load and more moment. That means more in the tension region of interaction diagram.

    It does. Simply use 3d.

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