NDS Code Interpretation 1

[msquared48]

Question is, under the NDS, can the 1.6 short term load factor be applied to a railing stanchion laterally loaded with the 200# required loading?

Personally, I think it can - can't do the 2.0 for connections, but the NDS has no mention of restricting using the 1.6 for connections.

Restriction for PT members understood, but this is a deck with no PT members... weather sealed...

Can still use 2.0 for the vertical member design...

Mike McCann, PE, SE (WA)

 

[JAE]

Are you talking about the railing vertical post (cantilevering off the supporting floor) or are you talking about the post-to-floor connection?

Here's some logic flow:
Per NDS, it refers out to the applicable building code for loads.
Applicable code in the US is IBC usually, which refers out to ASCE 7.
The 200 lb. load (or the 50 plf load) are defined under ASCE 7 as Live Loads.
Per NDS, the implied duration of load factor for combinations with live load is 1.0.

However, is the 200 lb. (or 50 plf) load a 10 minute load per the NDS Duration chart, or is it more like a 1 day...or a 7 day load?

I can't imagine a lateral load applied to a railing for more than 10 minutes.
Technically - a live load is a live load and per the strict logic in the code it would be 1.0.
But rationally, this railing load seems to be more akin to a 10 minute load - i.e. 1.6.


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[msquared48]

And it is not 10 minutes per se. It is really 10 minutes or less, the sudden impact load being at the lower limit of instantaneous.

I am talking the vertical posts supporting the top rail, and connected to the rim joist.

Mike McCann, PE, SE (WA)

 

[JAE]

So a serious drunk falls into the rail, passes out, stays in a permanent leaning position all night.

And he’s a very heavy guy so developing the 200 lbs is no problem.

So 12 hours would be appropriate. (All of the above taken from the NDS alternative commentary).

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[dik]

JAE... been there... a serious drunk would try to jump the rail...

Dik

 

[msquared48]

We cannot save the world JAE.

Serious drunks are expendable. I and my family were almost killed by one in 1977 and now have no sympathy for them. Absolutely none.

However, I do care about those he or she could hurt.

I'll get off my soapbox now...

I still think 1.6 is applicable here.



Mike McCann, PE, SE (WA)

 

[JAE]

Poor attempt at humor. Just imagine small children playing below the drunk at the rail...can't allow the rail to fail there.

Yes - 1.6 is appropriate in my book.

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[msquared48]

No worries, just been way too close to the end result for me.

Thanks.

Mike McCann, PE, SE (WA)