NBCC 4.1.5.14 Loads on Guards

[pbc825]

Hello All,

I'm about to be doing battle with a compliance architect for guard rails. Project specifications note, “railing assemblies and handrail attachments are to resist lateral force of 1kN at any point without damage or permanent set.” The load of 1.0kN is in accordance with NBCC 4.1.5.14 sentence 1 b); however, I interpreted the project specification to mean the guards need full resistance (per CSA-S16) but a load factor in excess of 1.00 could be omitted as the load needs to be resisted without permanent set. The compliance architect is of the opinion that a load factor of 1.50 should have been considered. Honestly, I don't have a strong opinion one way or another and feel this is a grey area.

Who agrees one should include a live load factor for loads on guards, and who agrees load factor could be considered to be 1.00?

Thank you in advance for your replies and comments.

 

[Guastavino]

I'm in the US, so take it for what's its worth. But I consider them to be a live load. It's certainly not a dead load. But again, I'm under a different code, and I may be wrong even here, but I'm on the conservative side of wrong.

Also, the whole "without damage" to me implies a service load to me. I'd hate to take something to an "ultimate" level and claim it was "without damage".

 

[jayrod12]

I count it as live as well.

 

[KootK]

I've struggled with this too as the language is inconsistent in NBCC between handrail/guardrail and specified/ultimate. Check out item eight of page eleven: Link. If you back calculate the safety factor from the load test values, it's always 1.5 (live).

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[SkiisAndBikes]

In the Ontario Building Code, which likely has similar wording to the NBCC, it calls for a "specified" load of 1.0 kN. The key word being 'specified'. When you look at various references in the Code, the specified loads are then factored as per the Code. In your example, the 1.0 kN specified load should be factored as a live load x1.5 for ULS calculations. I've completed a lot of guard design and seen a lot of other guard design by other engineers and they are all factoring the loads in 4.1.5.14. (well except for one company .... but that's a long story...)

 

[TLHS]

Yeah, the NBCC handrail references are pretty clear that they should be factored. There's all sorts of other irritating grey areas and inconsistencies in the handling of guards and handrails but I'm pretty comfortable that it's supposed to be factored.