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  • 1.  Outrigger System in High Rise Building

    Posted 10-04-2022 11:06 AM
    Hi Engineers & Professionals 

    I would like to ask about the effect of outrigger systems in 300 m high rise building shown in the picture  !! 

    I) What is the type of irregularity that can outrigger imposed in structure ? ( weak story , soft story , both of them , others  )
    2) When we check weak story irregularity   ,  we are interested in shear strength or flexural strength ? How we can assume full shear strength for flexural controlled members
    that may fail before reaching full shear strength ?

    3) How we can check weak story effect simply in practice design ?

    These questions are just same like brain storming to understand better !

    Regards ,

    Anas Dawas Aff.M.ASCE

  • 2.  RE: Outrigger System in High Rise Building

    Posted 10-05-2022 04:35 PM
      |   view attached
    I am always trying to start with my knowledge and after that , any body can correct me , 
    1) I think always that outrigger can not cause soft story or weak story because it lead to uniformly distributed stiffness and strength for few floors , 
    and we are adding outrigger to reduce lateral deflection not to impose irregularity inside the structure ,  

    2) When we check weak story ,  I think we should consider both ( shear and flexural strength ) , practically most of engineers are looking 
    for shear strength of lateral resisting members but I am asking always , how its possible to take full shear strength of the member while it may fail in flexure
    and shear force at that stage is much less than full shear capacity !! 

    Anas Dawas Aff.M.ASCE

  • 3.  RE: Outrigger System in High Rise Building

    Posted 10-05-2022 05:22 PM
    Hello Anas,

    I may be missing something, but it seems to me that the geometric change between floors does not affect the lateral system.  The columns which slope appear to be gravity-only.

    My understanding is that the weak direction of those red core walls relies on three exterior columns for stiffness (on the visible side), but these columns do not change position between floors.

    Christian Parker P.E., M.ASCE
    Structural Project Engineer
    Washington DC

  • 4.  RE: Outrigger System in High Rise Building

    Posted 01-24-2023 10:33 AM
    The Columns or the story that sways considered to have a weaker or softer effect in which it will give lateral deformation and deformed shape

    [Khalid ] [Zuiater] [Civil Engineer ]
    [Civil Engineer ]
    [Chief Contracting, Altorath International]
    [Abu Dhabi] [United Arab Emirates ]