Trench Grating Support

[jg_7554]

I'm working on a detail for a trench in an industrial setting which will service blow down piping for a series of boilers. I've attached a screenshot of the detail at its current stage, which is subject to change after this next round of feedback from the client. Are there any standards for how to support the grating over this trench? I currently have the grating supported by L2x2s with studs embedded in the concrete, welded on the angles at 12" on center. The PE I'm working with for this project has suggested this as kind of a 'legacy detail' he has always seen and used himself. I would think the detail would be governed by the failure of the concrete below the angle and the size of the grating used, along with pull-out of the angle-stud configuration. That being said, I can't find any literature to back these thoughts up and point me in a direction for a more detailed analysis of this situation. The grating is rated at the moment for a standard Light Manufacturing Live Load of 125psf.

 

[JedClampett]

We have a legacy detail just like yours. It's always worked. We also have a heavier detail for traffic that's deeper.
But if you're super worried, Zurn has trench and grate systems like this with rebates already designed for any load you could imagine.
Or, if you want to make a trench that will be remembered, Neenah Foundry, makes ductile iron systems that weigh a ton, but by god, they can take a load, up to aircraft.
I've honestly never done calculations on a rebate. But I think that the studs develop enough shearing surface that it can carry a grating load, plus a lot more. Not too mention that the downward load tends to improve the shear performance.

 

[dik]

Pretty similar to what I use, except SOG reinforcing is 2" from top. Attached some of my ealier ones, for info...

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1646774787/tips/TrenchDrain_lb4bpd.dwg[/url]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1646774787/tips/TrenchDrainMid_cpbtba.dwg[/url]

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1646774788/tips/TrenchDrainEnd_lbaabl.dwg[/url]

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[jg_7554]

I wouldn't say I'm super worried, this detail just peaked my interest because I wouldn't design this trench the same way if it spanned 6 feet instead of 2 feet or needed to be forktruck rated. I just thought I should have an idea for where my design came from instead of 'its just always been this particular way for this detail.'


Thanks, dik, I'll take a look at those too.