Using a Channel section as an intermediate support member for Grating

[oengineer]

I am working on an platform structure & I was initially looking to use a steel channel section as an intermediate support member for Grating (see image below):

The image above is from PIP STF05530 Grating Details, dated March 2001.

I have seen the use of channels as intermediate supports for grating on some old plans for access platforms structures.

But after looking in the latest PIP STE05530 Grating Design Guide (dated October 2007), I noticed that it states the following:

Then I noticed that the PIP STF05530 Grating Fabrication Details (COMPLETE REVISION), dated November 2006, shows an updated image for intermediate grating support framing. See image below:

It appears that the intermediate supporting member is now a Wide Flange beam instead of a channel section.

Is it not appropriate to use a channel section as an intermediate support for grating? I have seen it on some old platform plans. I feel like the use of Wide flange members would be excessive if the load & span is not that great/large, but I do not want to deviate from acceptable structural practices. Also, I would think channels in this situation would be more economical as long as the width of the channel flange is long enough to support the grating & grating clip (PIP states that the grating should have a 1 inch min. bearing on supporting steel).

Suggestions/comments are appreciated.

 

[r13]

Don't use channel when you have separate panels. Use back to back channels or tee can be considered.

 

[human909]

It is perfectly fine to use a channel as shown as long as you can comfortably meet the bearing width criteria. If your channel flange is close or below 50mm wide then you'll have trouble.

 

[oengineer]

Don't use channel when you have separate panels. Use back to back channels or tee can be considered.

At this point in my design, I do not know if the grating will have separate panels. How is that determined for the grating spanning between certain framing member?

 

[oengineer]

It is perfectly fine to use a channel as shown as long as you can comfortably meet the bearing width criteria. If your channel flange is close or below 50mm wide then you'll have trouble.

I am able to find a channel section with a flange width of 2 inches, but I saw this update from the PIP STF05530 Grating Fabrication Details (COMPLETE REVISION - dated Nov 2006), and it made me question the use of channels.

Why would PIP make this change? Have there been any structural problems arising from using steel channels as intermediate supporting members for grating?

 

[human909]

In my neck of the wood we usually have channel that is 65 or 75mm flange width so this isn't really an issue. Channel is routinely used for grating.

50mm wide flange is too small so find another approach (eg a I beam or back to back channels like r13 said.

 

[dhengr]

Oengineer:
There probably isn’t anything wrong with using the channels for intermediate members to support the grating. But, there are a number of things to consider:
1.) You need at least 1” of bearing for the grating, maybe more, so that limits the channel flange width to something more than 2” plus by the time you consider bolt hole clearances, washers etc., and you can’t have a grating joint over a channel without accounting for some joint gap and another line of bolt holes. You may need beveled washers. And, you may want a note on your drawing, ‘no grating joints over channel supports.’
2.) That channel support is likely an interior support, so it attracts more grating reaction due to the continuity of the grating. Thus, there may not be much weight savings in using the channel over a light W shape, and now you end up with two different connection details for the two different cross-framing member types.
3.) If you don’t have a lot of these members, the fabricator has to pull two different members out of stock to cut essentially the same length members from, for only a few members, and that and any other fab. changes will likely cost more than a couple lbs./ft. of material savings.

 

[bones206]

At this point in my design, I do not know if the grating will have separate panels. How is that determined for the grating spanning between certain framing member?

You can specify the grating panel joint locations on your plans. That way you have control over where the joints land.

 

[r13]

At this point in my design, I do not know if the grating will have separate panels.

Select span length per design load ad manufacturer's catalog cut.