Another IBC interpretation question

[haynewp]

Can anybody explain to me the reasoning behind footnote g under table 1604.3 regarding steel D + L deflection?

 

[Ron]

Note (g)..{g} For steel structural members the dead load shall be taken as zero.

Not sure it makes sense any more. Used to be common for stress determination, but not necessarily so anymore.

 

[haynewp]

Do you think it has anything to do with assuming that steel beams will be cambered for dead load?

 

[JAE]

haynewp - two thoughts that I have (that haven't been totally thought through):

1. Steel beams don't have long term creep effects (except for composite situations)
2. Steel beam specifications (by AISC) don't have D+L considerations and IBC is attempting to be consistent with AISC.

 

[AlohaBob]

I think JAE is correct in this. The issue in consideration is serviceability. Wood, Concrete, are subject to creep which will affect the serviceability of architectural finishes which the table specifically addresses. The finishes are expected to be applied after dead loads are in place. But with steel, further dead load applications are typically negligible and long term creep deflection is zero. You still need to watch live load deflections.