Application of 300 people in 'one area' provision for higher importance level structures?

[Agent666]

In AS/NZS1170.0 for determining the importance level of a structure, there is one provision that doesn't seem so clear cut (highlighted below). All the others are easy to evaluate as applying or not, however this one seems to be open to interpretation.

What is peoples interpretation of this particular provision, I'm guessing other loading codes around the world have similar provisions for higher importance structures. The fact it notes, in one area leaves it open to all sorts of interpretations (in my mind anyway) as there is no explanation of what one area is really meant to mean...

What would you consider as 'one area' in this context?

Something like an auditorium with seating for 300+ people with structure spanning clear over would qualify in my mind, i.e. that failure of the roof may impact on the magic 300 people.

But a foodcourt in a mall that seats 300+ people that's spread over several structural grids becomes less clear cut if it qualifies as one area with respect to these type of provisions.

My particular scenario is a retail mall, carparking + retail primarily, doesn't qualify for item (h) or (i) but depending on interpretation may qualify for (a)?

Anyone know of any code commentary from around the world that explains in black/white the interpretation of these types of provisions?

 

[KootK]

- I see what you mean, somewhat ambiguous.

- This is identical where I practice I believe.

- I've been interpreting "area" as "single contiguous space".

- I agree on your interpretation for the auditorium but disagree for the food court. I could easily see everybody bunching up near thee Sbarro, wherever the tables have been recently cleaned, or far from some obnoxious teenagers. I could also see them aggregating near an exit from the space in the event of a fire.

- I will acknowledge that I do see some logic in your foot court interpretation. A density of humans per square meter as the litmus test would appeal.

 

[Agent666]

Our current thought process is based on agreeing with the 300 people in one area and taking the entire building as a higher level importance structure, but this is primarily based on the fact that it might apply depending on what it really means, so the approach being taken is more along the lines of being better to be safe than sorry and avoid some potential argument with the reviewer down the line more than definitively applying some known criteria that's either black or white like the (b) to (i) criteria.

Which seems a bit dumbed down if the intent was to mean something completely different given the ambiguity, then we are unduly penalising the structure with 30% more lateral load. I'm easy either way, just wanted something to definitively go one way or the other rather than being on the fence and taking the more onerous condition because, well no ones really sure....

Now if it had said if the failure of a load carrying element had the potential to affect 300 people within the area supported or something it gives us a bit more to go on. But as written it seems you can interpret it anyway you like and with the lack of literature stating otherwise who's to say you are wrong or right. I swear sometimes the people who write these thing intentionally make it ambiguous because they don't really know either!


This reference seems to say its all about enclosed public areas, which I guess would apply.

This reference suggests an interpretation where it's all about simply having a dedicated space where 300 people could be crammed in.

I guess based on both of these then the foodcourt would satisfy these criteria, requiring the structure they are in to be designed for the higher loading.

 

[KootK]

Well, as you know, I'm often hesitant to take code language as gospel. I view code writers as fallible mortals, much like us.

This bears considerable resemblance to this thread of which we were both contributors, wouldn't you say?

 

[Agent666]

I'm often hesitant to take code language as gospel

Yeah, but sometimes it's there in black and white with no wriggle room, intent is 100% clear even if one disagrees with it! In this case they've given you enough rope to hang yourself if you are up for interpreting it in a certain way!

Yeah, similar thread but slightly different theme in that I'm ok with designing the entire building for the higher load if its warranted/dictated. That thread was mainly around exploring ways of trying to weasel out of designing the entire thing for the higher load and only doing the podium for the higher load as I remember it.

 

[Ron]

Under the code I work with (a subset of the International Building Code in the US), the term for this is "assembly occupancy". In my state, when the assembly occupancy is 500 or more people or has an assembly area of 5000 square feet or more, it triggers a special law that requires a specially qualified inspector for structural components called a "Threshold Building Inspector". The person must be separately authorized by qualifications as an engineer or architect with experience in this type of building. The designated TBI must be paid by the owner but reports to the local building authority.

 

[XR250]

For the mall scenario, I would consider the whole building. Hard to control how many and where people will congregate and where the structural grids will align in the future (i.e small shops may be converted into a Food Court)