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Rsj bearing help???

Discussion in 'Building' started by Jbg123, 29 Mar 2019.

  1. Jbg123

    Jbg123

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    Recently had an rsj installed as dinning wall has been removed. Rsj sits on internal skin on a pass time, but only has 80mm bearing on each side? Will this be okay??

    Thanks in advance
     
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  3. KenGMac

    KenGMac

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    Jbg123, good evening.

    Any chance of expanding on this please? is it a concrete pad?

    What sort of span does the RSJ cover? and what are the RSJs dimensions?

    Ken
     
  4. Jbg123

    Jbg123

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    Yes on a concrete padstone
    Span is 2850mm
    178x102x19 ub

    Thanks
     
  5. Notch7

    Notch7

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    Your builder has used a 3.0m beam -I would've thought either 100mm or 150mm is usually the minimum (cant remember which)
     
  6. tony1851

    tony1851

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    Although you would usually look for a 100 bearing, 80mm will be OK for the loading normally found in a domestic setting.
     
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  8. oldbutnotdead

    oldbutnotdead

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    Your BCO may want to see some calcs for an 80mm bearing, 150 is standard.
     
  9. noseall

    noseall

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    100mm is standard for steel beams.
     
  10. tony1851

    tony1851

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    The crushing strength of the average concrete padstone is around 50 N/mm²; when safety factors are taken into acount, this is reduced to around 20 N/mm².
    If the beam is 102mm wide, and the bearing is 80mm, that gives a contact area of approximately 8,000 mm², so that the maximum load allowed on the padstone surface would be 20 x 8,000 N = approx 160 KN.
    This is way, way above the load that will show in the SEs' calculations for the beam; it is not a problem.
    There are other factors to be taken into account when using a short bearing, but in practice they would not apply in a domestic situation where the loads are relatively low.
     
  11. Notch7

    Notch7

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    Its quite amazing really -it always looks so dodgy when you see a biggish steel with just 100mm bearing -I can see the logic in the maths though.
     
  12. ^woody^

    ^woody^

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    I'll chip in with the ubiquitous "what do the design calculations say"?

    Or are you printing out a thread from DIYnot and submitting it to the council for approval? :cautious:
     
  13. DIYnot Local

    DIYnot Local

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