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UmarMakhzumi

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Everything posted by UmarMakhzumi

  1. UmarMakhzumi
    Both of you are partially right about A307 anchor bolts. ASTM A 307 used to be the most common anchor bolt grade back in the 90s. Now it is ASTM F1554 and no one uses ASTM A307 any more. Also note that all structural bolts(not achor bolts-bolts that you shall use to connect structural members together) are mostly ASTM A325 high strength bolts- pretensioned in almost all cases. Now, as far as the topic is concerned, you can easily verify the capacity of bolts for both shear and tension. I am not very clear about what does "thread slippage" means. However, for the above case: Fu= 707 MPa Using a corrosion allowance for 0 mm, and 10 threads per inches, I get: Nominal Cross-sectional area of bolt= Ar = 285 mm^2 Net Tensile Area of bolt= An = 215.8 mm^2 Single Anchor Bolt Tensile Strength= T= Phi*An*Fu= 156.2 kN as per Canadian S16, 25.2.2.1 Single Anchor Bolt Shear Strength= V = 0.7*0.6*Phi*Ar*Fu= 84 kN as per Canadian S16, 25.2.3.3 (Threads intercepted in shear failure plane) You can do similar checks with other codes too. Thanks.
  2. UmarMakhzumi
    You can also do walk-ins. Thanks.
  3. UmarMakhzumi
    Waqar, What is your reinforcement ratio? Also, Uzair has raised a good point that reminds me of settlement under the raft foundation. How much settlement are you getting under the raft? Thanks.
  4. UmarMakhzumi
    There are two noticeable references mentioned in this thread. One is specific to Load Combinations(ASD stuff) and subsequent 1/3rd reduction, the other is about C12.13.4 of ASCE 7-05: 25% reduction of seismic overturning moment for the case of Equivalent Static Lateral Force Procedure. For some reason, all the replies have been focused on ASD Load Combinations and subsequent 1/3rd reduction. Anyways, ASD is old in a matter of few years would be completely wiped out of the scene for foundations. The current practice in industry is to use LRFD for foundation design. Moreover, make sure you touch base with the Geotechnical Engineer. Sometimes geotech reports specify what could be done or not with regards to thread subject. Thanks.
  5. UmarMakhzumi
    Karachi has a lot of great firms to work with but they dont pay well.. Try SMK ASSOCIATES, EA ASSOCIATES or MUSHTAQ BILAL ASSOCIATES. Thanks.
  6. UmarMakhzumi
    W/Salaam. You are very welcome guys. Thanks.
  7. UmarMakhzumi
    W.s. 1809.13 Footing seismic ties. Where a structure is assigned to Seismic Design Category D, E or F in accordance with Section 1613, individual spread footings founded on soil defined in Section 1613.5.2 as Site Class E or F shall be interconnected by ties. Unless it is demonstrated that equivalent restraint is provided by reinforced concrete beams within slabs on grade or reinforced concrete slabs on grade, ties shall be capable of carrying, in tension or compression, a force equal to the lesser of the product of the larger footing design gravity load times the seismic coefficient, SDS, divided by 10 and 25 percent of the smaller footing design gravity load. Site Class is specific to E or F. Individual Spread Footings founded on soil shall be interconnected... ; Ties shall be at foundation level. Thanks.
  8. UmarMakhzumi
    You should always do your due diligence. Most senior engineers in Pakistan have limited knowledge. Never listen to such people as they breed ignorance. Thanks.
  9. UmarMakhzumi
    I am a PE in three provinces of Canada. In a nutshell, you get more $$/hour and take responsibility for everything you design. If anything goes wrong, you are on the hook. Thanks.
  10. UmarMakhzumi
    Do design the raft for punching reinforcement if you cant provide enough thickness. Just because you have detailed a portion of raft as a beam doesn't mean it will behave as beam. Such concepts are a total misconception. Similarly, a lot of people go for 'concealed beams' in slabs which is totally useless. Like Rana said, increase your thickness locally or design it accordingly. Thanks.
  11. UmarMakhzumi
    Give the architect a call or talk to the client about what finishes he plans to use. You can't just assume anything. You need to have a basis to go back too. Thanks.
  12. UmarMakhzumi
    Rizwan Mirza should be doing everything and anything.
  13. UmarMakhzumi
    No clue but heard from someone that it is a good firm.
  14. UmarMakhzumi
    Rizwan Mirza Associates and Noor Durani Associates.
  15. UmarMakhzumi
    Superdead load for typical finishes would be aroud 40psf. You can always look up the architecture drawings to see what finishes are and apply appropriate loading. Thanks.
  16. UmarMakhzumi
    W/salaam. Welcome aboard. Thanks.
  17. UmarMakhzumi
    Welcome aboard!
  18. UmarMakhzumi
    The reason why foundations are tapered is because you need a certain depth to satisfy shear and moment at locations of distance d from support for shear and face of support for moment. Beyond these points your numbers are expected to be small and you should always verify BMD and SFD diagrams.There is no point in doing a tapered analysis. Thanks.
  19. UmarMakhzumi
    There are different recommendations for expansion joints in different books. I have seen no joints up to 200 feet in some text for RCC buildings. Anyways, you can do analysis for thermal differential case and see how much moment gets induced in your foundation. Visit the link below for information about carrying out thermal analysis. http://www.sepakistan.com/topic/1367-effect-of-temperature-changes-on-buildings/ Thanks
  20. UmarMakhzumi
    Khalid, You might want to look at this thread too for long term deflection: http://www.sepakistan.com/topic/85-long-term-deflection-multiplier/ Regarding 1), I am not sure as I have been out of commercial building engineering and using ETABS for more than 5 years. Other people may be better able to answer you on that. Thanks.
  21. UmarMakhzumi
    That is a great book!
  22. UmarMakhzumi
    There are situations where this provision is helpful. To quote a real example, Saudi Embassy building X amount of schools in Northern Regions of Pakistan. Majority of buildings shall fall to SMRF and probably two or three would go under IMRF. In such situations, you can use the higher SDC and keep things simple for construction and your field team in-terms of drawings and rebar detailing. Thanks.
  23. UmarMakhzumi
    Providing lap splices at mid height is a pain in neck from a constructability point of view, probably thats why code recommends it for the case of SMRF only where ductility demand is the highest. Regarding omitting splices, I am not sure what the complete sentence is and its context. I have to look it up and let you know. Thanks.
  24. UmarMakhzumi
    For the first picture(strap type), I would model the foundation and beam in ETABS, get the reactions at foundation and export them to Safe. Beam gets designed in ETABS and foundation goes to Safe with loads representing effect of beam presence. Second and third pictures are easy, you can take average thickness and use them. I haven't used Safe in over 5 years now so. I am not sure if there has been a new feature to accommodate such fdns but I don't see any problem there. Use simple slabs with conservative thicknesses.
  25. UmarMakhzumi
    Welcome aboard. Thanks.
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