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UmarMakhzumi

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Everything posted by UmarMakhzumi

  1. UmarMakhzumi
    Regarding 2), your understanding is correct that there wouldn't be excessive drift b/w basement stories, however real challenge that I see would be to design diaphragm for the seismic force transfer at podium or ground level. Elastic earth pressure deflection at beam colum joint should be very small to negligible if you have slabs at that level. Those supports are infinitley rigid as your slabs at joint level wont let the joint move(as slabs bending would be in-plane). The use of static coefficient for lateral earth pressure to design basements supports(where slabs are present at joints) supports my scribble. Just a thought. Thanks.
  2. UmarMakhzumi
    Bending inside would provide more confinement, improving ductility of joint. Outside is more what construction site guys are used to do. I don,t know why they like it that way.
  3. UmarMakhzumi
    A lot is going on this thread, and I would just point out 1 thing regarding "hinge type base plate". Your base connections can be fixed or pin. Depends where you place your bolts around column. If bolts are insider flanges, its pin, if outside, fixed or moment. You will have to design the baseplate accordingly. Also the connection of column to baseplate matters and you can achieve a pinned connection by welding in a special way but to keep things simple, assuming fully welded column to baseplate, stick to bolt layout to determine if its pin or fixed. Rest, you can transfer the loads like you said. Follow free body. Thanks.
  4. UmarMakhzumi
    Then its a normal building and same rules to apply and you are very likely to have some kind of irregularity because of un-symmetric framing.
  5. UmarMakhzumi
    You cant have a limit, because basement is your base. Even if you want to check the same interstory drift limits for say 20 story under ground basement, it would always satisfy because of extensive walls all around. You can do a thought experiment to confirm this. Thanks.
  6. UmarMakhzumi
    Rana, The basement should be moving with the ground. The argument can be justified as code requires us to design structures by calculating time period of structure using the height above grade only. Depending upon what kind structure you are designing with a basement, your basement may act merely more than a basement (Backstay Effect) http://www.sepakistan.com/topic/1448-location-of-base-for-seismic-design/ http://www.sepakistan.com/topic/1480-diaphragm-flexibility/?hl=backstay Thanks.
  7. UmarMakhzumi
    FEMA is a very good resource for evaluation and retrofitting of existing buildings. See the link below and some quick snaps from the document. http://www.fema.gov/media-library-data/20130726-1450-20490-3009/fema_172.pdf
  8. UmarMakhzumi
    View > Set 2D, Select the Z elevation where you want to see the plane. Thanks
  9. UmarMakhzumi
    W.Salaam.An excellent question. Ductility in beams can be studied easily be considering the moment-curvature relationship and basic beam formula, C=T. Over reinforced sections have insignificant section ductility as no yielding would be there. With the increase in reinforcement ratio , strain in reinforcement decreases and the depth of neutral axis increases, resulting in a lesser value of section ductility. Same is true for condition in which value of Fy is increased and all other parameters are kept constant. Thanks.
  10. UmarMakhzumi
    Here are a few articles for bed time reading related to your questions. Enjoy! CNCE 454- Desgin of Concrete Structures.pdf Stresses in Beams.pdf
  11. UmarMakhzumi
    L/5 and L/3 are detailing rules and work for most practical cases. If you go by the book, then you have to check what Chapter 12 states.
  12. UmarMakhzumi
    All reinforcement shall comply to Chapter 12 of ACI Code that satets min requirements to develop reinforcement in different loading scenarios. Thanks.
  13. UmarMakhzumi
    It should be connected. I have seen consultants not connecting it too. It comes again to how the consultants define SOG rather that what an actual SOG is.
  14. UmarMakhzumi
    Thanks for posting such a good reference. Section 5.2 lays the criteria for how to determine if the footing should be termed as rigid or flexible. However, under 6.1, the document states It pretty much comes to judgement.
  15. UmarMakhzumi

    Yo Johan!

  16. UmarMakhzumi
    Zain, Could you post the source/ reference for the method described in Torsional Constant For Beams in ETABs.docx document? Cheers.
  17. UmarMakhzumi
    You don't have any other choice but to assume a rigid raft if you are doing it manually. It would be way too complicated to solve manually if you consider a flexible mat. If you are using a computer software, you can consider both options to see the effects on your results.
  18. UmarMakhzumi
    Here is updated description with more information. See the attached image. Thanks.
  19. UmarMakhzumi
    O/S means overstressed or it fails. Thanks.
  20. UmarMakhzumi
    Here is what we do in Canada as per S16; Design your pile as a beam column. You can download the Canadian Handbook from google. Just search CISC Steel Handbook. Thanks.
  21. UmarMakhzumi
    The Etabs Concrete Design Manual is posted here.
  22. UmarMakhzumi
    I found another version, scanned slightly better, its attached below. Rectangular Concrete Tanks - PCA - US.pdf
  23. UmarMakhzumi
    W.salaam. It depends upon what kind of model you are working with. If you are working with a simple 2-Way Slab Beam System, automesh would be the best to go. If your model is very complicated then you have to see what kind of mesh elements you need. Here is a list of all the new updates to ETABS. The page says that ETABS 2013 has "Enhanced Meshing Capabilities with More User Control" https://www.csiamerica.com/products/etabs/news You can also check out the following link that discusses all the new features including updates to meshing in detail: http://www.csiamerica.com/products/etabs/features Thanks.
  24. UmarMakhzumi
    Thats correct. However, If you have a very special design mix it could have a different unit weight. Thanks.
  25. UmarMakhzumi
    http://www.sepakistan.com/topic/1326-seismic-design-guide-for-masonry-buildings/?hl=masonry Thanks.
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