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  1. EngrRC

    Concrete cover for piled rafts

    They're bored piles for a tall building, and they're mainly in compression, but will also have some uplift. For the raft, the cover requirement is 75mm, but due to pile embedment (and if spacers are required to lift the bars from the pile head), it will more.
  2. EngrRC

    Concrete cover for piled rafts

    HTURKAK, yes, it is mentioned that 3inches above the pile head is assumed in CRSI. But why is this required? Considering the pile head is embedded 100mm into the raft, the total cover for the reinforcements will now be 175mm.
  3. EngrRC

    Concrete cover for piled rafts

    CRSI Design Guide for Pile Caps shows a minimum embedment of pile into the pile cap by 4 inches, and then the bottom reinforcements are to have 75mm concrete cover above pile head. Is this valid for concrete piles or is this just for steel piles? I do not see the need to have 75mm extra cover...
  4. EngrRC

    Seismic design base shear to ASCE7-16

    I am designing a tall building to ASCE7-16. I have designed the superstructure using response spectrum demands (scaled to match the equivalent static force base shear). However, I am designing the foundation based on overturning moments from Equivalent Static as mandated by the approving...
  5. EngrRC

    Shear wall lateral system - what is the minimum percentage

    My question stems from the code specification that if frames are participating in the lateral response, then they need to be designed for seismic provisions - this is applicable for dual systems where beams and columns are acting as moment frames. This can be a stringent requirement especially...
  6. EngrRC

    Shear wall lateral system - what is the minimum percentage

    I am designing a building with lateral resisting system composed of shear walls to ASCE 7-16. Vertical resisting system uses frames and shear walls. Some earthquake base shear is taken by the columns - is there a limit (minimum %) for which the "shear wall system" no longer becomes applicable...
  7. EngrRC

    Encased composite column shear stud design to bending

    Composite column is used throughout multiple levels of the building, so yeah the encasement is continuous over many floors, but terminates somewhere near the top of the building where RC columns are used. Floors are prestressed slabs. My strategy is to use shear studs to resist loads introduced...
  8. EngrRC

    Encased composite column shear stud design to bending

    For a multi-level encased composite column, how do you design the shear studs for the shear/bending within every floor level? AISC offers three methods (external force applied to steel / to concrete / concurrently) - which of these is applicable for that mentioned above?
  9. EngrRC

    Composite Column Shear Studs

    Thanks for the response Icebloom. Your explanation matches with my understanding - that the shear studs only need to be designed for the transferred force at that level, and the axial force from the composite column above shall not be considered in the stud design. Just that I do not see enough...
  10. EngrRC

    Composite Column Shear Studs

    Does anyone have a reference that explains in detail how the shear studs of a composite column are designed and where they need to be provided? In particular, I have this confusion: For a multi-level composite column subject to compression load only (for simplicity), do the shear studs have to...
  11. EngrRC

    Circular Hollow Section - Maximum Thickness

    What is the maximum thickness that is possible (in terms of fabrication) for a circular hollow section? I have cases wherein I need an 800mm circular section with 80mm thickness.
  12. EngrRC

    Wind drift - Can drift due to gravity loads be subtracted?

    Exactly as you pointed out @slickdeals, the building is asymmetric and with alternating floor plates causing the lean. The only effect that I am considering to take out is the instantaneous drift due to the structure's own weight (e.g, floor 'n' leans towards y direction, while floor 'n+1'...
  13. EngrRC

    Wind drift - Can drift due to gravity loads be subtracted?

    Structure lateral system is RC walls with outriggers. There are planted columns supported on steel transfer trusses at mechanical levels. phamENG, you may have misunderstood. I am referring to lateral displacement due to gravity loads (not vertical displacement) that's causing exceedance of...
  14. EngrRC

    Wind drift - Can drift due to gravity loads be subtracted?

    In ASCE7, wind drift is evaluated using load combination of 1.0 dead + 0.5 live + Service wind. If I run two nonlinear cases (A) 1.0 Dead + 0.5 Live + service wind, and (B) 1.0 Dead [w/o Facade loads], can I evaluate the drift as A-B? My thinking is that wind drift is concerned with...
  15. EngrRC

    Reduction of foundation overturning (ASCE 7-16 Cl. 12.13.4)

    Has anyone used this provision for piled raft design? I intend to use this to reduce the pile loads coming from earthquake. I've seen some people say that this is only for overturning/soil stability, but from the commentary, my interpretation that this 25% reduction in overturning moment can be...
  16. EngrRC

    Overstrength factor for wall supporting planted column

    The planted column is not part of the lateral resisting system. From the commentary you mentioned and the applicability limitations, I understand that overstrength need not be applied.
  17. EngrRC

    Surcharge Loads for Retaining Wall Design

    Imagine your building foundation is right next to the retaining wall. With this you would use the usual surcharge formula with the building foundation bearing pressure as surcharge load. If it is further apart, the solution will be either a Boussinesq (point load) or parallel strip surcharge...
  18. EngrRC

    Overstrength factor for wall supporting planted column

    I am designing a concrete wall which carries a transfer beam supporting a planted/floating column. ASCE7 mentions the wall should be designed for seismic load with overstrength factor. Now, my question is does all the seismic load resisted by the wall (coming all the way up from uppermost...
  19. EngrRC

    Global Buckling Load Factor for Truss

    Hi Rick, My question applies to both roof truss and truss bridge. My question relates to the procedure of designing a truss. Let me rephrase. In designing trusses, do we have to make a separate global buckling analysis (be it linear or geometric non-linear)? If so, what is the buckling load...
  20. EngrRC

    Global Buckling Load Factor for Truss

    JoshPlum, I just read the chapter. So there is no need to run a separate eigen buckling analysis because the AISC strength checks already consider this?

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