Integrated Buildings & Structures

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Joint thickness in RCC building frames

  • 1.  Joint thickness in RCC building frames

    Posted 03-16-2021 07:39 PM

    We know columns beams joints in RCC building frames congestion of reinforcement bar's is a problem handling with great care. Joints may break because of expansion of steel bars . Additional thickness and rebars shall be given to beams on column support section. Some eccentricity will give torsion resistance also while designing joint thickness won't take into account which is an error in the safe side. My question is, how to develop frame moments in a RCC frames?



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    Alex Thomas R.Eng, M.ASCE
    CochinAlexThomasR.Eng, M.ASCEIndia
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  • 2.  RE: Joint thickness in RCC building frames

    Posted 04-22-2021 08:25 AM
    Hello @Alex Thomas, in my opinion, the quantity and arrangement of rebar in a structural element are characteristics to consider in the design process, the designer need to attend the quantity rebar limits, the position of bars and size of hooks to develop and adecuate bond and anchorage resistance, the space betwen column and beam bars with respect to the sorruonding concrete, the quantity and position of confinament bars. Most of the design codes include a "Bond and Anchorage section and a Detailing section" wich stablish those limits and caracteristics in a joint, for example. As a god reference I like the old but great book "Reinforced Concrete Structures" from Robert Park and Tomas Paulay and its really illustrative chapter "The Art of Detailing".
    I hope my comments area useful.​

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    Horacio Galicia-Gaona Ing., S.E., M.ASCE
    CEO
    Morelia
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  • 3.  RE: Joint thickness in RCC building frames

    Posted 04-22-2021 10:46 AM
    How do we get the effect of being simply support in single bay single story portal frames, giving L rebars at the columns support the beam ?





  • 4.  RE: Joint thickness in RCC building frames

    Posted 04-23-2021 08:55 AM
    If you need that effect, in my opinion the best way is disconnect the beams from the columns, and build separatly members, and use a bearing system that functions like hinge (elastomeric bearings per example), it is usally in simple span bridges, with this you can avoid cracks at the "joint". Any other way needs a rebar detailing that no aport flexural strength at the joint, maybe you can do it with column rebar with lack development length or providing so short effective depth at the joint, but with this you need to wait at the moment of concrete cracking to loose any flexural strength.
    Why do you need this?

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    Horacio Galicia-Gaona Ing., S.E., M.ASCE
    CEO
    Morelia
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