Opal Tower - Sydney Australia 28

[CivilEngAus]

https://www.news.com.au/national/ns...s/news-story/dad28af4aad5ff11cf968102635824f9

https://www.smh.com.au/national/nsw...ns-building-may-collapse-20181224-p50o4b.html

This could be an interesting and developing story in Sydney Australia. A 34 storey near new residential apartment tower in Sydney has been evacuated this afternoon over fears it is in structural distress with cracking noises heard during the day and one or more cracks developing; emergency services are treating it as a major incident.

Given we already have some of the toughest building codes in the world (although little to no registration requirements for engineers) it will be interesting to see how this plays out and what the crack(s) looks like to cause such a major emergency response.

 

[degenn]

confinement provisions

So just to be clear, you believe the correct interpretation of 11.7.4 requires all walls designed as columns that are over 50MPa must be restrained to 14.5.4. In other words 11.7.4(a) cannot be used, even though not clearly stated.

Moving to 14.5.4, this clause in intended for an IMRF ie mu=3. Is this still applicable if mu is 1 or mu is 2. The reference from 11.7.4 places no qualifications. Should the reference simply say the provisions of Section 14 for columns be considered (which they obviously should be anyway).

You can have, say, 2500x250 65MPa blade column which doesn’t pick up much in plane moment if the core is much bigger, say 9000x9000. It may satisfy 11.7.4 or may not using mu=1. This would allow no ties or normal ties (at 250 centres) depending on load, if the first part of 11.7.4 is used and since it is Ok with mu=1, Section 14 has few requirements. If the last paragraph is used and no exemption is allowed for mu=1, then you need closed ties (not 90/135 hooks) at 125 centres for the full wall height.

There are big cost differences depending on how the clauses are read.

 

[rapt]

You will have to wait until the amendment is out. I cannot preempt what will be finally decided.

I am just pointing out that the 10.7.3 limits on special confinement in their current form are not really applicable for earthquake situations where there is a lot of plastic response required after the "nominal" elastic design load is reached. So the "nominal" elastic design load cannot be used to determine when special confinement is required.

 

[human909]

Human909,

Says something for our universities then doesn't it.

Yes. Pretty much.

In the context of many of the significantly experienced people commenting here, I'm relatively green and still inexperienced, especially in concrete as my career has taken me a different but still very interesting direction. I participate here out of curiosity and hopefully can learn and provide some thoughtful insight.

Plenty of structural engineers just seem to follow codes without thought or consideration of reality. I know my knowledge is limited. But when "inexperienced me" catches mistakes from people who are supposedly experts it positively scares me.


Meanwhile one of the more significant line items in the final report is this one:

"The viability of residents re-entering the building extends beyond the structural issues considered here and hence beyond the scope of this investigation. Nevertheless, we would recommend that items 9-11 listed above be completed prior to re-occupation."

That is the line that residents and lawyers will be jumping on.

 

[rapt]

TomFh and DeGenn,

if you want some reading on it,

 

[mangotree]

It would be good to have a Part 2 of the Final Report, with a follow up on the rectification work.

It’s not bad that there will be further checks in place on the professionals, but I think that is the easy and more politically palatable route.

The harder issue to deal with is that the builder/ developer are the party with the real control of the whole construction process. If one of the professionals insists on a rectification of a defect for instance, the builder may very well remind them of who exactly they are working for and paying their firm’s fee.
It’s a result of how the design and build contract is structured.

It’s difficult to envisage a future where the politicians would ever “crack down” on developers/builders!! If anything, it would be the exact opposite.

So if for instance, the builder insists on completing one floor every 6 days. Would the concrete floor or beam have reached adequate strength within the 6 days to support a load bearing precast panel, such that they can progress to the next level? Sure, if you test it after 28 days it would have adequate strength, but how about after 6 days?

Would the structural engineer be responsible for the builder’s or developer’s decision to achieve a certain completion timeline?

And what “power” exactly would the engineer have contractually to determine the procurement of the project- that’s the builder’s domain.

Even if all the professionals were registered, there’s an unequal power play in force, that is out of the professionals’ control.

(If the professionals' next pay cheque is coming from the builder they are checking)

 

[epoxybot]

If I'm following this correctly, the city nor any other geographical governing body retains a copy of the building plans, permits, inspections or approvals?

 

[rapt]

The rules are already in place for checking and certification of buildings. If they are not being performed correctly or are being corruptly manipulated, there are rules already in place for that too.

So what do we do, create more rules that say that the existing rules must be enforced! Oops they are already in place too.

Engineers are supposed to design to the building regulations. They are supposed to ensure that the building is built to spec. Certifiers are supposed to make sure that the checks have been carried out correctly.

I know I am old fashioned and come from an age when engineers and for that matter, most people in construction, felt an obligation to ensure that construction was performed correctly, but creating new rules and commissions and authorities is a waste of time and money. There have always been builders, engineers etc who were willing to break the rules to save/make money. That is human nature. It happens in all walks of life. Some are just worse than others.

You can regulate all you like but to me society is heading on a path where regulations do not matter to more and more people. More regulation just costs the honest people more money. It does not solve anything. And if you look back through history, it is simply repeating what has happened before to just about every age in human history.

 

[mangotree]

I have total confidence in the honesty and integrity of the consultants wanting to do their job as expected of their profession.

Their traditional “position of authority” has been effectively taken away, however, if they are left vulnerable to progress payments from the builder to practice.

These “Design and Construct” contracts can be structured such that the developer only pays the builder. The builder then is in charge of the whole project and it’s budget, which includes paying the architect, structural engineer, civil engineer, mechanical engineer, hydraulic engineer etc.

The consultants have been effectively turned into nominated subcontractors, and are susceptible to be treated as such.

That’s a vulnerable position to be in, especially when these consultants are expected to “sign off” on the project.

If the consultants were not paid directly by the builder, but by the owner, then there would be more autonomy (which is the more “traditional” building contract).

If this weakness is not addressed, I fear the whole “registration” process won’t be enough to solve future issues.

 

[rapt]

The old model where the owner/developer appointed and paid the consultants has always been my preferred model. But once Project Managers took over the construction side of things and convinced the owners that it was better for them to control the whole process from design to construction, the current model became inevitable.

But there are many problems with your proposal that the PM/Builder appoint the consultants but they be paid by the owner/developer. eg
- Payments still have to be agreed/approved by the builder
- in many cases the builder and developer are not exactly at arms length and often are the same company

In my view, the consultants activities should not be negotiable, eg full supervision of the construction should be carried out by the design consultant. One developer/builder on the Gold Coast used to only require the consultant check every second floor pour. Unfortunately one time I know of, one of the "odd" floors was a major transfer floor with very large PT beams. And he did not check it! And full design should be at least overseen and approved by the consultant, even if some parts are subbed out to specialists at the request of the builder.

And checking by an independent 3rd party (not another group in the same consultancy) should be mandatory. This could be controlled by the Certifier and paid by the owner direct to the 3rd party checker.

The Certifier should be appointed by the relevant authority, not the developer/builder.

 

[degenn]

And checking by an independent 3rd party

And there needs to be some mechanism to limit the exposure of the third party checker to damages to reflect their reduced fee, otherwise no one may be interested in the work.

 

[Agent666]

degenn, in NZ the company I used to work for doing peer review work would limit the liability to 10% of the original designers liability as part of the standard conditions of contract under which the work was usually done. This was an additional condition the company imposed for peer review work.

But I agree, if there is a problem in the future as the peer reviewer you could in theory get dragged into it an be liable. I've only heard of it happening once and the company who did the peer review were cleared of any wrong doing because if the designer had actually addressed the issues raised in the review (and to some degree been a whole lot more competent around some of the particular aspects relating to the construction), then perhaps the building would not have collapsed during a storm event.

As someone who has been constantly battling 'bad design' in peer reviews, I believe there should be some sort of independent audit of designs (random or targeted) to make sure minimum competencies are being meet within industry, it's been talked about for ages here as being required. Fail a review and get fined as an Engineer or loose the right to practice, personal accountability! Simply waving a rule book at engineers like rapt is noting does nothing, hit companies where it hurts. Make the findings public, let the market decide?

I suspect if you did this though, we'll run out of engineers in a few years and I'm busy enough already...

 

[rapt]

Also, it should be necessary for the structural designer to resolve all disagreements with the checkers to the satisfaction of both parties.

As I understand the situation with infrastructure D&C projects, as least in NSW, the structural designer is obligated to consider the checking engineers comments but not required to come to agreement on a resolution.

I know fee structures have been ruled against in Australia as being anti-competitive, but I also think there should be minimum fee schedules for different types of work to ensure that the designer has time to put in the effort to design and detail it properly.

It is farcical that the structural designer might get sigificantly less than 1% when the real estate agent gets 2.5% every time he sells it!

 

[Ingenuity]

It is farcical that the structural designer might get significantly less than 1%...

...and with liability for a lifetime. Crazy!

 

[QSIIN]

1%!?!? What kind of luxurious industry are you consulting in!!!??? Half that is considered generous!

But you are right about D&C and unfortunately we engineers have cannibalized ourselves by undercutting each other, further driving down fees. And if we don't be competitive with fees, the contractor boots us off the job in favour of their own engineer who will detail the job the way that suits them. We've been threatened multiple times by contractors to get rid of wall ties and make everything precast, singly reinforced and dowelled, because "their other engineer did it on their last job".

And the problem is, many chartered/registered/RPEQ or what-have-you engineers are the ones we are talking about in this thread, lacking in thorough understanding of seismic theory (amongst other areas). Hence why their fees can be so low, because they don't need to consider seismic, they don't need to consider progressive collapse! Because they don't even know what that is! And no one is there to stop them!

My main issue is that becoming registered is just a fee. You merely purchase your right to sign off on structures, and most companies pay that yearly fee for you. 3 to 5 years out, fill out a couple forms and write a report and (now) a phone interview, and you're qualified to sign off on a 50 storey building.... she'll be right.

Agent666, I don't think we'll run out of engineers, we'll just cut the fat. And the rest can do the job properly.

 

[rapt]

I did say < 1%!

Otherwise I agree completely!

 

[CivilEngAus]

My main issue is that becoming registered is just a fee. You merely purchase your right to sign off on structures, and most companies pay that yearly fee for you. 3 to 5 years out, fill out a couple forms and write a report and (now) a phone interview, and you're qualified to sign off on a 50 storey building.... she'll be right.

Do CPEng and RPEQ applications not require face to face panel interviews anymore?

 

[Retrograde]

Do CPEng and RPEQ applications not require face to face panel interviews anymore?

I believe it is now up to the discretion of the of reviewer.

 

[Agent666]

In NZ the CPEng assessors just whittle down the applicants practice area until they pass. ~90% pass rate as far as I understand it, compare that to other comparable/equivalent licensing around the world (IStructE/PE/SE, etc), I think IstructE is something like 30% for first time applicants?.

So if you aren't deemed competent in a certain aspect that you wanted to be endorsed to do based on the evidence of work you provided (i.e. your best cherry picked work supposedly), then they remove this aspect until they end up with something they think you might be competent in doing based on what you submitted.

Its supposed to be based on demonstrating that you can operate on your own, to develop solutions to complex engineering problems, manage the process of design/construction etc. Very little applicants seem to hit this mark based on discussions with the assessors I personally know, but they feel obliged to pass them with caveats on their practice area. The danger is these people don't know what they don't know.

CPEng is not really seen as a measure of technical competency, which I personally believe it should be, because there is nothing else to distinguish engineer A from B to the unsuspecting public.

They talked a while back here about introducing a higher certification for 'complex structures' (which was never defined). As far as I know its gone nowhere and wouldn't have addressed the perceived failings of the original CPEng system.

 

[FreddyNurk]

CivilEngAus, I'm aware of a couple of people who have followed the process outlined (resume, forms, phone interview) to gain RPEng, which is then accepted by BPEQ as an acceptable assessment. I believe that BPEQ may have done their own assessments at one stage, but now its via an accredited assessment authority (EA, AusIMM, Professionals Australia etc).

The CPEng assessment requires a lot more report writing as far as I'm aware, as well as the panel interview, but there's a hefty cost for that compared to Professionals Australia. The people that I'm aware of that have followed the Professionals Australia path were all over 10 years experienced, which may have made a difference. None of them were seeking Structural though.

EDMS Australia

 

[Settingsun]

I believe that the RPEng was offered by Professionals Australia because the CPEng/EA assessment was considered too expensive (cost and time) by many people. I can see their point. About two years ago, an associate technical director asked me (as project manager) to sign off one of his project reports. I had to sign it off three times as he apparently wasn't quite able to guess the exact wording EA needed to see. The revisions came to me 1-2 months apart and I couldn't tell what had changed without having the different versions side-by-side. This was an engineer you'd have on all your projects if he was available and you had the budget.

Being a large company, we also had an EA-approved graduate program. This gave us a steady stream of 3-5 year experience engineers who gained the CPEng credential comparatively smoothly. The process seems flawed when you witness this sort of thing as it appears skewed to getting junior engineers into the CPEng system.