[COM] City Central 8 | 72m | 20lvls | office

[UrbanSG]

Sounds good

Is it 18 or 20 levels? I'm confused because it has changed so many times.

[Ben]

Sounds good

Is it 18 or 20 levels? I'm confused because it has changed so many times.

Good Question... i have no idea what the final building height is.

[UrbanSG]

I suppose either way it is going to be great to finally see a decent sized building like this one going up in this section of Franklin Street. Will make a big change to this area. Bring on the others further west along Franklin Street too next.

[skyliner]

Sounds good

Is it 18 or 20 levels? I'm confused because it has changed so many times.

My guess is 18 - in keeping with the floor number of so many other bldgs - like an invisible ceiling reached there. Does anyone know if the magical 18 is/was linked to the dreaded airspace issue.

ADELAIDE - TOWARDS A GREATER CITY SKYLINE

[Wayno]

My guess is 18 - in keeping with the floor number of so many other bldgs - like an invisible ceiling reached there. Does anyone know if the magical 18 is/was linked to the dreaded airspace issue

Don't believe so. ACC height limit for buildings facing Franklin St is 72m (PA-17) and the aircraft OLS (obstacle limit surface) limit is approx 100-110m (above sea level) - so plenty of headway. Approval *can* be obtained to breach the OLS from the relevant authorities (AAL, CASA, DOTARS) on a case by case basis. It's unclear whether developers know this fact.

[skyliner]

Many thanks for that Wayno. In my earlier observations of bldg heights(1980's) I was baffled by the big 18 - hence my comment in my last post. (A little bit of a
shot at the situation in my previous comments too must admit). )

ADELAIDE - TOWARDS A GREATER CITY SKYLINE

[monotonehell]

Many thanks for that Wayno. In my earlier observations of bldg heights(1980's) I was baffled by the big 18 - hence my comment in my last post. (A little bit of a
shot at the situation in my previous comments too must admit). )

ADELAIDE - TOWARDS A GREATER CITY SKYLINE

It's possibly the magic number that pops out when all things are weighed like; trying to find enough tenants, risk/return, getting finance etc. I'm betting it's a combination of what the market can take and what the investors are willing to risk.

[skyliner]

Many thanks for that Wayno. In my earlier observations of bldg heights(1980's) I was baffled by the big 18 - hence my comment in my last post. (A little bit of a
shot at the situation in my previous comments too must admit). )

ADELAIDE - TOWARDS A GREATER CITY SKYLINE

It's possibly the magic number that pops out when all things are weighed like; trying to find enough tenants, risk/return, getting finance etc. I'm betting it's a combination of what the market can take and what the investors are willing to risk.

Do you think this all holds equally true then as is now - what the market can stand is similar now?

ADELAIDE - TOWARDS A GREATER CITY SKYLINE

[monotonehell]

Do you think this all holds equally true then as is now - what the market can stand is similar now?

It's possible the developers/investors (being risk adverse) are still working from old copy books. Or it might actually hold true. Not being privy to the actual risk assessment process they use I can only speculate. But risk avoidance is the usual reason for why everything is done the way it is, even if the reasoning used isn't correct. Innovation in business isn't as common as people like to think. Mostly people just do what's worked in the past, until it stops working, or someone finally does innovate in a game changing way and beats everyone out of the market.

[Isiskii]

It could also possibly be that the reason many buildings are ~18 levels in Adelaide, is due to the geology upon which our city stands on. As I understand it, the earth/bedrock is predomininately clay, which is a very volatile material when influenced by earthquakes and other tectonic/plate movements in the area - ie; the fault line in the Mount Lofty Ranges.

So I'm guessing that there is a certain mass/weight which the building can be built up to to a safe standard on its own that will withold the impact of any potential earthquake that may affect the city and that critical mass is achieved at around the 'mysterious' 18 level mark. This is particularly relevant to CC8 which has cross-bracing on it, namely for earthquake restistance purposes.

Wild stab in the dark, but seems pretty logical to me?

[Nathan]

And yet Tokyo, which is far far far more earthquake prone, is building the Tokyo Sky Tree at 634m high. I don't think building over 18 levels and keeping it safe for the odd tremor is much of an issue.

[Isiskii]

...the earth/bedrock is predomininately clay, which is a very volatile material when influenced by earthquakes and other tectonic/plate movements in the area...

Tokyo might not be sitting on a bedrock of clay, hence why it can build the 634m SkyTree Tower. I don't know what kind of earth profile Tokyo sits on, whether it's limestone, or sandstone, etc. which affects a building's durablity and resistance to tremors because its properties may be less volatile than that of clay.

[Omicron]

Why are so many buildings at or around 18 storeys?

Well, er, the Hilton, GHD, State Administration Centre, former Reserve Bank, Education Department, Commonwealth Law Courts, Wakefield House, half of City Central, the Commonwealth Bank Building, Angas House, former ATO on KWS, half of Grenfell, former Hooker House, and 1 KWS are all in the same 72m height zone, and these days they can squeeze in ~15 storeys into the 55m zone surrounding, which includes the student apartments on Bank St, the Stamford Plaza, Roma Mitchell on North Tce, Embassy, Horizons, anything on Hindley, some of Grenfell, and so on and so forth.

So nothing special. Just an arbitrary figure that has been decided upon.

[AG]

It could also possibly be that the reason many buildings are ~18 levels in Adelaide, is due to the geology upon which our city stands on. As I understand it, the earth/bedrock is predomininately clay, which is a very volatile material when influenced by earthquakes and other tectonic/plate movements in the area - ie; the fault line in the Mount Lofty Ranges.

So I'm guessing that there is a certain mass/weight which the building can be built up to to a safe standard on its own that will withold the impact of any potential earthquake that may affect the city and that critical mass is achieved at around the 'mysterious' 18 level mark. This is particularly relevant to CC8 which has cross-bracing on it, namely for earthquake restistance purposes.

Wild stab in the dark, but seems pretty logical to me?

You're correct in saying that Adelaide is sited on a large layer of clay (called Hindmarsh Clay), but beyond that your point is flawed and does not make sense from an engineering point of view. In general, when larger and taller buildings need support they rely on piles that are driven deep into the ground into deeper more stable ground or bedrock where possible (these types of piles are called end bearing since most of the support is due to the bedrock at the pile base). In the case of Tokyo, since there is no bedrock in many areas of the city they rely on a different form of pile called a skin friction pile which draws its strength from the rough contact surfaces between the pile and the surrounding soil. Tokyo's soil profiles are definitely far more tricky for heavy structures than in Adelaide, although it is somewhat lucky that most of its tallest buildings in Shinjuku are in the region that does have bedrock. The case for building up to 18 levels is more of an economic and financial issue rather than an engineering limitation (modern geotechnical engineering is good enough to have heavy buildings capable of being supported in even the worst soils).

[iTouch]

to be honest I think the issue of many buildings in the cbd being 18lvl is just massive coincidence to which we're are thinking WAAAYYY too much about