Mascot Towers - transfer beam cracking 8

[Tomfh]

https://www.smh.com.au/sydney-news/...nts-in-the-basement-area-20190614-p51xwt.html

More cracking apartments. We’re doing well in Sydney at the moment...

 

[CivilEngAus]

Letter to residents the day prior to the evacuation and which provides some info: [URL unfurl="true"]https://cdn.newsapi.com.au/image/v1/9421b9a85b24867636d66880e876f11d[/url]

 

[Artisi]

Appears as if a worrying trend is developing. Very pleased I don't own a high-rise apartment in Sydney.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Agent666]

Following the same format as opal, limiting damage mode ensues by all parties involved..
it wasn't me


Interesting that it noted building is 10 years old. Some articles state the issues started when another more recent building was built adjacent. Perhaps some differential settlement due to dewatering or similar?

 

[georgeverghese]

This tower is also above an underground train station - Mascot; while in the previous Opal tower incident, the tower was directly above the Olympic Park underground train station.

 

[msquared48]

Vibrational settlement?

Mike McCann, PE, SE (WA)

 

[Tomfh]

They're saying that transfer beams are sagging/cracking/failing? So it appears something is wrong with the structure.

Be good to have some actual photos of this supposed cracked transfer beam.

 

[CivilEngAus]

Some new photos within

https://www.news.com.au/national/ns...s/news-story/79f2fcc04d274ef5fd8eaaa0147d8f0f

 

[Tomfh]

Some new photos within

https://www.news.com.au/national/nsw-act/news/shoc...

The articles notes that there are actually two separate defects. This recent one, which the owners have just put up $1.1m for emeregency works, and an separate pre-existing structural fault at a slip joint, which is estimated to cost $4m, which they have known about for several years.

 

[Settingsun]

I haven't seen who the designer/s and builder/s were. Have they been identified?

 

[NorthCivil]

question for australian engineers here:

I've heard there is no licensing scheme for structural engineers that is required outside of queensland.

So any old chump can hang a shingle, regardless of qualification, training or experience, and offer structural design consulting services?

Also inferred in these articles, is that there is no hard requirement to have the design engineer carry out site inspections, that duty is for another party - i might be wrong on this one?

 

[NorthCivil]

Just trying to get to the bottom of what is wrong with the industry structure that allows this kind of issue to arise. Any ozzies want to chime in?

 

[CivilEngAus]

I've heard there is no licensing scheme for structural engineers that is required outside of queensland.

That is correct; however in my experience in NSW a lot of approval bodies (local government, private certifiers) will request that a chartered structural engineer (CPEng) certify that the design has been completed in accordance with relevant standards. The approval authority is generally not qualified to review the engineering hence relies on the engineers self certification. Victoria is introducing an engineering licensing scheme at the moment similar to the Queensland system and I have a feeling that NSW isn't going to be faraway after the negative publicity of Opal Tower and now Mascot Towers.

Also inferred in these articles, is that there is no hard requirement to have the design engineer carry out site inspections, that duty is for another party - i might be wrong on this one?

You've hit the nail on the head. Australia is not like the US where my understanding is that the design engineer often inspects the structure during construction. I am only involved in low rise design and construction and in a lot of instances either the local government (Council) building surveyors or private firm certifiers inspect the works, neither of which are normally engineers. The contractor constructing the works will only engage an engineer to inspect the works during construction if the approval authority tells them that they must obtain a report/letter from an engineer approving certain structural components. Said engineer does not need to be the design engineer (nor a registered/chartered engineer typically). That being said, both Mascot Towers & Opal Tower are major projects that would have required significant private engineering inspections (signoff letters/reports) during construction to satisfy the building certifiers and who no doubt many of the engineers involved in those projects would already be chartered engineers. Mandatory engineering registration will do little to stop another Opal Tower, Mascot Towers or similar in my opinion.

I've been the private inspecting engineer engaged by multiple contractors on low rise projects designed by other firms. In my experience, once you won't 'tick and flick' sign off on whatever it is that they are doing in contradiction to the approved drawings then they stop getting you to undertake said inspections and find another firm who will sign off on what they are doing. It is frankly a joke and is akin to doctor shopping; needless to say I don't do a huge amount of inspection work anymore. On the design side, we are engaged to inspect < 5% of the design works we undertake as per Australian industry convention our engagement typically finishes once the design is complete/approved. The other 95% + of projects is either inspected by the (not engineering qualified) building inspector or not inspected at all.

 

[Tomfh]

however in my experience in NSW a lot of approval bodies (local government, private certifiers) will request that a chartered structural engineer (CPEng) certify that the design has been completed in accordance with relevant standards. The approval authority is generally not qualified to review the engineering hence relies on the engineers self certification.

This is my experience too.

Australia is not like the US where my understanding is that the design engineer often inspects the structure during construction. I am only involved in low rise design and construction and in a lot of instances either the local government (Council) building surveyors or private firm certifiers inspect the works, neither of which are normally engineers

We work on to to medium rise government/commercial/resi and we invariably inspect our own designs from start to finish. I’d be surprised if Opal and mascot towers weren’t inspected by the designers?

That being said, both Mascot Towers & Opal Tower are major projects that would have required significant private engineering inspections (signoff letters/reports) during construction to satisfy the building certifiers and who no doubt many of the engineers involved in those projects would already be chartered engineers. Mandatory engineering registration will do little to stop another Opal Tower, Mascot Towers or similar in my opinion.

Agree. The registration issue is a bit of a red herring in my view. It will be the same people doing the work, they’ll simply have another set of red tape to deal with.

The issues are deeper in my view, and are more to do with the general race to the bottom in terms
Of engineering fees and “innovative” building techniques.

 

[human909]

(I'm still a relatively new in the industry. So take my views as you will. I'm pretty jaded with the structural engineering profession in Australia.)

Traditionally I would say that Australia has had better regulation and general controls than the US. I would say that still generally true across most aspects of work and life. Even likely true about the construction industry too. But as we are touching upon here, it doesn't seem to be the case regarding engineering in the construction industry.

The thing is it seems that actual practising engineers have long been cut out of the building process. They are merely consultants on most projects and on smaller projects they may never even come on site. The only engineers who are regularly on site are the project managers who care more on time and on budget because that is what they are being payed to do. (Not do a well engineered job.) On the other side of the coin OH&S administration is through the roof, and I wouldn't say that part is irrelevant there is only so much site and project managers can do.

So who is inspecting that the work is done correctly? Well, um.. Often nobody. If you have a good crew then you may not need much oversight most of the time. And even if they had oversight, many structural engineers wouldn't know their way around a working site well enough to provide oversight. Because like was said above:

On the design side, we are engaged to inspect < 5% of the design works we undertake as per Australian industry convention our engagement typically finishes once the design is complete/approved.

The big problem with this IMO is that the engineers who actually doing the design often don't have much 'ownership' over projects.

 

[human909]

We work on to to medium rise government/commercial/resi and we invariably inspect our own designs from start to finish. I’d be surprised if Opal and mascot towers weren’t inspected by the designers?

I've mostly worked in industrial construction for manufacturing firms. I don't think I have ever seen one of the structural engineers come on site during or after construction for inspection.

Mind you I'd say construction in the industries I have worked in doesn't face the same race to the bottom. The building owners are normally in it for the long haul and the firms bidding for the contracts are normally keen to get the job done right so they maintain the relationship.

 

[Settingsun]

I don't think registration will change much. Design for Queensland projects isn't done any differently than for other states. Registration can be a low bar too. Large companies run graduate schemes that are registered with the assessment body for a fee. Of course, this means almost a rubber stamp of chartership for graduate engineers in these schemes after only three years.

'Any old chump' setting up as a structural engineer would have a hard time getting any major projects because of lack of insurance. No developer wants to be left with the bill if something goes wrong and they can't sell their apartments.

Let's also not get carried away: Opal and Mascot were built ten years apart, have resulted in a total of zero injuries, and both will be repaired and remain in service. Compare/contrast with the Miami bridge by registered engineers. Or any other US collapse.

What Australia has is high immigration and property prices which have drawn more developers into the market boom and stretched the engineering and construction industries. Quality probably slipped a bit but hopefully the decay will now be arrested.

In terms of inspections, this varies widely depending on the client as noted above. IME some contractors want inspections because they see it as letting them off the hook if there are problems. "The engineer signed it off, must be a design problem."

 

[human909]

Let's also not get carried away: Opal and Mascot were built ten years apart, have resulted in a total of zero injuries, and both will be repaired and remain in service. Compare/contrast with the Miami bridge by registered engineers. Or any other US collapse.

I don't think we gain anything by playing "which country has better engineers and construction". The only reason why the comparisons came up was simply to elaborate on construction regulation and conventions in Australia.

Can the engineering and construction be improved in Australia? Yes. Has there been many issues plaguing the industry recently? Absolutely. Do I need to bring up flammable cladding? That stuff was known about for years before anybody bothered to actually address the issue.


I do agree with you regarding registration. And I also believe the issues are more about the building industry rather than about engineering failings. But in current environment poor workmanship all over the place are more likely. The only thing less likely is somebody falling off a step ladder and twisting an ankle. ;-)

(My current project doesn't even allow a small step ladder on site.)

 

[NorthCivil]

Up in Canada, (not that we dont have our issues -

https://www.cbc.ca/news/canada/british-columbia/john-bryson-engineer-surrey-high-rise-1.5125884)

The engineer (or their representative) is required to submit 2 forms the the AHJ -

1. Assurance of Professional Design and Commitment for Field Review
2. Assurance of Professional Field Review and Compliance

It gives the engineers a lot of power over the construction - If the builder doesn't do things as the design engineer requests, they dont get the final sign off from the engineer and they cannot close the building permit.

Its a nice system I find - if you designed it, you know the fundamentals of the structure you are inspecting, what are the key parts - where you can give the contractors leeway, and where high level workmanship is essential.

 

[Tomfh]

They are now reporting that some parts of the building are sinking:

https://www.smh.com.au/national/nsw...est-engineer-update-says-20190625-p520wm.html

It isn’t clear in the reporting how that relates to the cracking.

I wonder if dewatering the hole next door contributed? That area is very low lying and you have to pump a lot of water out when you dig big holes.