Deflection Criteria IBC/ACI

[wioletta]

Dear All,

I am a structural engineer based in UK. My recent job is to design a mezzanine floor (composite deck on steel frame) and I have been given deflection criteria that is based on IBC/ACI. I quote below:

'Deck shall not deflect by a factor exceeding L/240 when the deck is maximally loaded according to IBC Section 1604.3 and ACI 318. This is the ratio of the deflection amount over the width of the deflection area (L) using cumulative deflection including deflection from imposed loads and from the deck itself'

And here comes my question. In essence am I to design individual members, i.e. secondary and primary composite beams to deflect no more than l/240 under combined dead and imposed load (option 1 on the attached mark up), or am I to design a floor panel that will deflect less than l_diagonal/240.

I would really appreciate any guidance on interpreting the above.

 

[Bagman2524]

I think the L/240 applies to all the members. Any members where excessive deflections impact the operation of other components (i.e. doors, windows, equipment, etc.) need to meet L/240

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