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UmarMakhzumi

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  1. UmarMakhzumi
    W.Salaam. I personally don't have ETABS installed but I can help you locate and fix the error if you can share the analysis log file here. Please upload it here. Thanks.
  2. UmarMakhzumi
    W.salaam... You need to find bearing pressure under the tie-beam due to factored applied loads and design the tie-beam for that loading. You can superimpose reactions under column due to gravity and due to settlement and then find the pressure under tie-beam using those reactions. Thanks.
  3. UmarMakhzumi
  4. UmarMakhzumi
    Excellent share..here is the framing for Citi Corp Tower
  5. UmarMakhzumi
    Please see the discussion here: http://www.sepakistan.com/topic/1307-etabs-load-combinations/ Thanks.
  6. UmarMakhzumi
    In my personal opinion, slabs and meshing is where 90% of load transfer error lies. I would recommend, never to model slabs; do the load distribution yourself and assign diaphragms manually. For the above case, you can delete the existing slab and zoom in the area to draw a new slab that snaps to the corners. Also do check your analysis log. There is a .log file created after every analysis in the same directory as where your model is located. Open that file in wordpad/ notepad and print it and go over each line. Thanks.
  7. UmarMakhzumi
    You're very welcome Yasir. Eid Mubarak to you and you family too! Thanks.
  8. UmarMakhzumi
    Uzair, I haven't come across the second approach. Have you seen that happening with individuals or as a practise at a firm? Thanks.
  9. UmarMakhzumi
    Yasir, You can use 0.24 kPa if your roof is non accessible or there are no maintenance and construction loads on roofs which I believe is the case. Thanks.
  10. UmarMakhzumi
    Yasir, The attached drawing is not clear. Do you have architectural plans that show the information about how your canopy looks like and the way structural framing supports it. Regarding the criteria for max deflection, you may have to check multiple ones . Canopy members supporting edge of glass should be checked against L/175. Thou shall consider twice the length for cantilever members in this check. Thanks.
  11. UmarMakhzumi
    There is no technical reason behind that statement. I am just not used to the term.
  12. UmarMakhzumi
    You are correct, however, my comment was more in terms of considering soil as springs. Good Discussion everyone! Rana, is your problem solved? Where are you with it?
  13. UmarMakhzumi
    Partially fixed is not the right word to say, in fact SAP2000 just distributes load based of relative stiffness of members. There would be rotation. Thanks.
  14. UmarMakhzumi
    It will act as resisting member. My previous reply is about the role of bracing only. Why don't you make a built-up section instead of bolting two members together? And even if you bolt them together, make sure it goes all the way down.. Don't cut it before the end. Your system doesn't look good to me. You will have to check a lot of limit states in this case. As far as bracing at sides is concerned, If your structural analysis shows that you need bracing at the sides, provide it. If you don't need it you can skip it. Regarding the top bracing, It should be continuous to engage all members. Even if its not continuous that would be acceptable too. Thanks.
  15. UmarMakhzumi
    I just noticed that you are asking about tension only "cables". I havent used cables in Sap2000 but they should never take compression. Please see the tutorial at CSI webpage to see how to define tension only bracing. I am not sure if the tutorial covers cables but cables by default should be tension only. http://www.csiamerica.com/content/sap2000-09-tension-only-bracing-watch-learn Thanks.
  16. UmarMakhzumi
    I have posted ground snow load values for different cities in Pakistan based on IBC 06, International Building Supplement. Have a look here: http://www.sepakistan.com/topic/1503-design-snow-load/?p=3477 Thanks.
  17. UmarMakhzumi
    I have done some search in my content dump, and I found ground snow values(kN/m^2) as well as wind speed values(m/s) based on IBC 2006, International Building Supplement. The values are for Karachi, Islamabad, Peshawar and Lahore only. Here are the two pre-notes that go with the attached tables: Here are the two foot-notes that go with the attached tables: Now regarding design values for places like Murree or Northern Pakistan, which receives biggest chunk of snowfall, my personal recommendation would be to use values for Fort McMurry, Alberta, Canada. You can use this link(http://www.jabacus.com/engineering/load/snowload.php) to quickly calculate snow load for Fort McMurry or any city in Canada. To establish a baseline, you can do a comparison of average annual snowfall for Fort McMurry(or whatever city you selected: Edmonton, Saskatoon and Regina would be some good choices in addition to Fort McMurry) to the area that you are designing to get a feel for how conservative your number are. You may have to some search on google for Pakistani Cities average snowfall data but it would be worth it. Do share it here if you come across any. This sums up my 2 cents. Thanks.
  18. UmarMakhzumi
    Wsalaam Khurram, Water tank wall thickness has to do with how deep the tank is. You can use the following PCA publication to design your tank. http://www.sepakistan.com/topic/16-rectangular-concrete-tanks/ A few considerations would be finishing interior of tanks by chips(local name, I don't know what the engineering name is) to make it water tight as well as using water stop at construction joints. Thanks.
  19. UmarMakhzumi
    Walikumaslam! When drawing members, select Continuous as Moment Release. It would be modelled as a rigid connection. I am not sure if I understand your question correct. Thanks.
  20. UmarMakhzumi
    Tension-only elements in ETABS Tension-only elements can be modeled using the nonlinear version of ETABS. The process is as follows: Select the elements to be specified as tension-only. Specify the tension limit (usually a limit higher than expected maximum tension capacity) and a compression limit of zero (or negative) through Assign > Frame/Line > Tension/Compression Limits. Run a nonlinear static or nonlinear time-history analysis. This is necessary since tension-only assignment is a nonlinear feature. Any load case or combination may be converted to a nonlinear analysis as follows: Select the case(s) through Define > Convert Combos to Nonlinear Cases. Run a static-linear analysis, then once complete, run a static-nonlinear analysis (only required in V9, in V13 linear and nonlinear cases will run at once) Add the nonlinear case(s) to a user-defined combination with a scale factor of 1.0. Apply the nonlinear combination as design load. Perform design. When full nonlinear behavior must be considered, nonlinear time-history analysis should be run since response-spectrum analysis only applies to linear systems. Further, response-spectrum loads cannot be converted to nonlinear cases. Source: https://wiki.csiamerica.com/m/view-rendered-page.action?spaceKey=etabs&title=Tension-only+elements+in+ETABS Also see: https://wiki.csiamerica.com/m/view-rendered-page.action?spaceKey=kb&title=Tension+and+compression+limits+tips Thanks.
  21. UmarMakhzumi
    Please see the topic: Seismic Assessment And Retrofit Design and go through attachments. Thanks.
  22. UmarMakhzumi
    This bracing would not do any contribution to your lateral force resisting system other than acting as a diaphragm. Share your sketches. How big the frame is? What is the member spacing ? Thanks.
  23. UmarMakhzumi
    Okay, here is something important that I wanted to write but didn't had the time as I was travelling. I doubt if you can do that. The reason is that basement wall backfill would least likely to be compacted. Imagine doing that would increase load >> significantly which is not desired. Normally the lateral spring coefficients provided by geotech report are for undisturbed soil or soil well compacted. Dumped backfills would provide much softer springs that I would suggest be considered as void regions (Same thing as designing a pile for lateral). That is correct. However, If you have basement walls all around, then you get equal lateral pressure, thus net force on diaphragm due to lateral earth pressure is zero. However, I appreciate your comment as for the building being discussed basement walls are unsymmetrical. But, if you consider the lengths of basement wall and all the lateral force resisting system, the stiffness would be huge and I don't expect a significant response in unsymmetrical case, but, it depends on a lot of variables and number crushing in every situation is required before judging the situation. Good Catch though! Exactly! For Rana, I would suggest to keep modelling approach simple unless deemed necessary. For buildings with a number of basements, if you really want to complicate things, you should probably check your stiffness for basement below stories and basement above stories and use 2 different R values for both systems and apply recommendation in code for 2 different R systems. Thanks.
  24. UmarMakhzumi
    If you are still getting higher drift b/w basement stories,, you should share your framing with base shear distribution along height. I am positive that would be helpful to discussion. Thanks.
  25. UmarMakhzumi
    Thanks Uzair
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