Long Term Deflection of Grating

[Naggud]

Hello,

I'm currently working on a project that has been going on for a number of years. The specs were written a few years back (before I came to this company). Our Fiberglass Pultruded Grating spec asks that 'certified test results verifying the long term deflection criteria for a seven day duration test'.

The vendor has asked us to explain to them what type of test is acceptable for this as it is non-standard they say. I haven't been able to find any useful information for this type of testing online. There doesn't appear to be much info on long term testing procedures for FRP grating unfortunately.

Has anybody encountered this before? Does anyone know of a document that covers these procedures or similar?

Thanks very much.

 

[JAE]

Here is an ASTM link for D-2990: Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics

http://www.astm.org/Standards/D2990.htm

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[Naggud]

Thank you very much. I have a CD for the ASTM Standards in Building Codes but it doesn't carry this standard. Instead I found the D2990-01 version. I think that will be sufficent for my needs right now.

Again, thank you.

 

[dicksewerrat]

The D2990 test takes 10,000 hours and is extrapolated out to what ever life cycle you are looking at. Make sure the lab gives you the formula they use to get the 10 year, 20 year, etc value.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[EngineeringEric]

10000 hours? that is a 1.15 year long test.

 

[3DDave]

EngineeringEric, you should see the excitement that paint fade testing is under sunshine and weather!

Some tests just can't be accelerated; either the loads, chemical processes (eg under heat), or the amounts of energy put in to make a test go faster cause the item to either fail in ways they would never do or allow a pass because failure modes had no time to progress (oxidation, moisture, contamination.)

We had one testing company claim a lubricated bearing would fail; the bearing is used in oscillation at ~1 RPM for a few minutes a day with ample time for an oil film to form from grease in grease channels between uses. They cranked it to the maximum load it would ever see and single direction at a few hundred RPM; reported that it was failing due to overheating. But they did lube it at the same 500 hour intervals requested.

 

[dicksewerrat]

Yes it is. We sometimes have to do this test to get the 'hold back' amounts paid on projects. You may want to look at ASTM D790 and D 638

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Naggud]

Thank you guys. Dickseweeat you're right - that's the basis for the test as I understand it.

We went with the testing procedures set out in ASTM D790. To cover ourselves we've added steel under the grating at the locations where point loads are supported (so even if the grating is inadequate we'll be able to support the equipment on the grating).