Structural steel paltforms deflection criteria

[Charan5]

Hello,

I am intersted to know what deflection criteria to be used on steel platforms with grating. (L/240 or L/360). And if grating strength can be used to assume the platform beam top flange laterally braced to select smaller members.

 

[BAretired]

Deflection doesn't matter much with steel grating. Live load deflection of L/360 is usual.

Beams supporting steel grating may be considered laterally braced if the grating is welded or otherwise attached to prevent lateral movement of the beam.

BA

 

[csd72]

I would not treat standard steel grating clips at lateral restraint but definately if they are welded e.tc.

I would think L/360 for live load deflection would be conservative as people would expect an access grating to move more than a habitable floor. L/240 sounds more reasonable to me.

also, if there is a good chance that there will be futuere modifications or additions to this platform then you will not win friends by cutting things right down to the bone. It is much easier to brace an unrestrained beam than to have to replace it.

 

[rscassar]

L/360 overall and L/500 for live load only. I never assume that the grating provides restraint for LTB (lateral torsional buckling). It has been discussed on this forum before and I'm sure that many of my colleagues would agree.

 

[Charan5]

Thank you all for the feedback. I am assuming live load of 60 psf and collateral&dead load of 20 psf. I am considering using L/360 for live of 60 psf and for (live load 60 psf + col& dead load 20 psf) using defelction criteria of L/240. Will this be good design criteria.

I also agree your comments on lateral restraints on grating, I do agree, unless it is welded, we can not consider as laterally braced.

 

[Charan5]

Hello,

I would appreciate if some body can comment on my assumptions.

 

[csd72]

I would also allow for the fact that you could have a 200lb person standing anywhere on the platform. This is usually critical when you have short spans or cantilevers.

Hard to comment on the 60psf as this really depends on the situation.