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GDE collapses onto Barton Highway

By 17 August 2010 128

[First filed: Aug 14, 2010 @ 15:54]

Bridge collapse

The Canberra Times brings word of a new and sorry twist in the tail of the Gungahlin Drive Extension with a major collapse of the new work over the Barton Highway:

Firefighters have freed a man trapped under a section of the Gungahlin Drive extension that collapsed this afternoon. Stage two of the extension has collapsed onto the Barton Highway while construction work was underway around 2pm.

Everyone on site at the time of collapse has been accounted for. The Emergency Services Agency said paramedics treated 15 people at the scene, and 10 would be taken to hospital in stable conditions.

More as it comes in. If you have pictures please send them in to images@the-riotact.com

UPDATE: The ESA has this to say:

3:10pm Saturday 14 August 2010 – Update two – no serious injuries 15 people being assessed on scene by intensive care paramedics with up to 10 to be transported to hospital in a stable condition.

No critical injuries at this time.

2:35pm 14 August 2010 – Update person freed One person confirmed trapped on scene has been freed by firefighters.

2:15pm Saturday 14 August 2010 – Report of construction collapse ACT Ambulance Service and ACT Fire Brigade responding to reports of a construction collapse on the Barton Highway Gungahlin.

Update to follow

FURTHER UPDATE: This grim warning on the traffic implications from the ESA:

4:10pm Saturday 14 August 2010 – Final update on partial bridge collapse ACT Ambulance Service has transported a nine patients to the Canberra Hospital in a stable condition with minor injuries following a partial bridge collapse on the Barton Highway Gungahlin.

The section of bridge that collapsed was under construction adjacent to an existing bridge.

The injuries range from limb to suspected spinal.

A total of 15 patients have been assessed on scene by intensive care paramedics.

One man was trapped for around 15 minutes until he was rescued by firefighters.

The ESA was alerted to the incident just before 2 o’clock.

The road is expected to remain closed for quite some time.

ANOTHER UPDATE: The ABC has word from roads supremo Tony Gill:

“Our initial advice is that it could take up to two weeks before we are in a position to remove the debris and get the road open for public use,” he said.

“We are getting an independent engineer’s report just to get an understanding of how the bridge collapsed and secondly we need to engage a demolition contractor to remove the debris.

“But we also have to make sure it is safe for that demolition contractor to go in and remove the debris.”

ONE MORE UPDATE FOR THE ROAD: The TAMS websites has this morning (16 August) put up a statement dated 14 August on the road closures (file data says it was created this morning):

The ACT Government wishes to advise motorists and other road users that Barton
Highway, at its intersection with Gungahlin Drive, is closed (in both directions) until further
notice.

Barton Highway (Northbound): All northbound traffic will be detoured via Gungahlin Drive, Ginninderra Drive, Baldwin Drive and William Slim Drive to reconnect with Barton Highway.

Barton Highway (Southbound): All southbound traffic will be detoured via Gungahlin Drive, Sandford Street roundabout, and Gungahlin Drive to reconnect with Barton Highway.

Gungahlin Drive (Southbound off-ramp): Right turn onto Barton Highway will be closed.

Traffic will be able to turn left from Gungahlin Drive onto Barton Highway towards the city,
however people are encouraged to detour via Mitchell.

Detour signage has been erected to alert people of the closure and to direct traffic.

The ACT Government apologises for any inconvenience caused.

For up-to-date information on road closures please call Canberra Connect on 13 22 81.

Slideshow below:

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128 Responses to GDE collapses onto Barton Highway
#91
Jivrashia5:45 pm, 16 Aug 10

H1NG0 said :

the one on Belconnen way looked dodgy hanging out over the intersection over the past few weeks. It appears as though it could easily collapse

Crap… Good point.
The people who did the supporting frames for the Barton Hwy may have also done the one for Belco Way.

Could we get kiwieng’, Arthur McKenzie, and tooheyspils observation on this?

#92
johnboy6:34 pm, 16 Aug 10

I’ve already asked TAMS that question. Waiting for a reply.

#93
ex-vectis8:19 pm, 16 Aug 10

We drove past there on Sunday and my wife said, jokingly, theres 50 workers just standing around waiting for another collapse. We are supposed to live in a civilised society; its third-world countries that see regular building and bridge collapses.

Not a ‘skills shortage’; dreadful mis-management. Again. Are any of us safe?

#94
Arthur McKenzie8:31 pm, 16 Aug 10

Jivrashia said :

H1NG0 said :

the one on Belconnen way looked dodgy hanging out over the intersection over the past few weeks. It appears as though it could easily collapse

Crap… Good point.
The people who did the supporting frames for the Barton Hwy may have also done the one for Belco Way.

Could we get kiwieng’, Arthur McKenzie, and tooheyspils observation on this?

As I said before I don’t know whether it is safe or not.

In practical terms I have no reason to trust the safety management of the site while the bridge is being built so I stay away from the area. I have only ever driven under it once or twice and prefer to take an alternative route. It’s only a couple of extra minutes, just not worth taking the risk.

#95
Madashell8:52 pm, 16 Aug 10

I’m gunna give Arthur McKenzie 8 out 10. I’m taking two points off one for having a crack at same sex couples who want to get married (how the hell is that any skin off our noses) and 1 for missing that the splices are not mid span but more like quarter span. I will say that the the top flange weld was a bit light on as far as I am concerned but was supposed to be in compression and only failed after the beam had rolled.

Lateral torsional bracing is clearly miles short of what was required (any kid with a mechano set could tell you that) but I hear the mistake was on the drawings so subby is not at fault. Dam shame that the unions are kicking the subby’s head in the media when the problem was not of his making. Not much justice out there at times!

#96
Arthur McKenzie10:04 pm, 16 Aug 10

Madashell said :

I’m gunna give Arthur McKenzie 8 out 10. I’m taking two points off one for having a crack at same sex couples who want to get married (how the hell is that any skin off our noses) and 1 for missing that the splices are not mid span but more like quarter span. I will say that the the top flange weld was a bit light on as far as I am concerned but was supposed to be in compression and only failed after the beam had rolled.

Lateral torsional bracing is clearly miles short of what was required (any kid with a mechano set could tell you that) but I hear the mistake was on the drawings so subby is not at fault. Dam shame that the unions are kicking the subby’s head in the media when the problem was not of his making. Not much justice out there at times!

Good onya Madashell,

You’ll have to remind me where I made the same-sex couple remark. I don’t recall that one. If I did then I take it back because I couldn’t care less. Until you do that puts me back at 9/10.

As for mid span vs 1/4 span, I take your point. However it doesn’t really matter much, for three reasons – a) the missing top flange plates are more significant, b) the Steel code requires a minimum splice strength wherever it occurs on the span, and c) it doesn’t appear to me to be the primary cause of failure, the welds were working after the collapse. That puts me back to 9.25/10.

As for lateral torsional buckling, you’ll understand that what I am driving at is lateral stability which is a different mode of potential failure. My assessment is the beams tipped over and would not have reached any sort of torsional buckling. They were on the ground way before that happened – and that’s what I saw on site – the beams don’t exhibit a primary torsional buckle. You might find a buckle in the flanges but that would be post failure too. Back to 9.5/10.

As for blaming people I don’t think I blamed the subbies, I don’t even know who they are and couldn’t care less about them. If the CFMEU hate them then that’s not my affair. Back to 10/10.

Be careful of what kids with meccano sets tell you, I listened to a Structural Engineers.

Thanks for reading. Your idea of giving people marks is OK, but I think it might be better concentrating on giving marks to the people involved in this current failure. Give me 0/10 if you like but don’t forget your tax dollars aren’t affected with what I get.

#97
Madashell10:10 am, 17 Aug 10

I was using “lateral/torsional” in an all encompassing sense but if the beams really are 760UB’s as someone suggests then the top flanges are fairly compact and we can strike one up for you and call it a purely lateral buckling failure. If they are indeed 760 UB’s then BHP hasn’t knocked them out for years so it is second hand steel which explains the extra boltholes and splice requirements. Nothing wrong with recycling mind you as long as you do it right.

On the point of not caring. Well I am not a child but I am passionate about children’s rights. I am not religous but I believe in religous freedom. I am not a female but I care very much about their rights. Certainly I am not gay but I care very much about their rights also – getting off topic I know but you are not getting that whole point back until I ring some empathy out of you.

The kids with the mechano sets to which I refer are the ones who destroyed every other toy from birth. The kids with a wild fasination for how thing break and who stack blocks to unbelievable heights performing all sorts of torcherous balancing acts. The kids who saved like demons and stole money from their sister’s piggy banks to get that mechano set. These are the kids who will for the rest of their lives look up and have their gut tell them instantly that that ain’t right. Trust those kids I tell you trust them! If they choose to become structural engineers then my friend they will be the ones you want designing your bridges because for them it is in their blood in a way that no amount of book reading or finite element modelling will ever teach.

#98
kruse69au12:22 pm, 17 Aug 10

Arthur Mackenzie wrote:
“As for blaming people I don’t think I blamed the subbies, I don’t even know who they are and couldn’t care less about them. If the CFMEU hate them then that’s not my affair. Back to 10/10″.

I know one of those injured and he is facing up to 6 months in hospital and then a further 12 months of Rehab. He has a young family and is a great bloke. He was an site to do some screeding. But you dont know him so you dont care.

#99
p112:38 pm, 17 Aug 10

Looks like things were well progressing the 7th July. Shame you can’t quite tell if all the bolts were done up from aerial photos though.

#100
Grail1:37 pm, 17 Aug 10

I’m just wondering what empathy towards same sex couples has to do with any of this discussion, Madashell?

#101
Arthur McKenzie3:10 pm, 17 Aug 10

kruse69au said :

Arthur Mackenzie wrote:
“As for blaming people I don’t think I blamed the subbies, I don’t even know who they are and couldn’t care less about them. If the CFMEU hate them then that’s not my affair. Back to 10/10″.

I know one of those injured and he is facing up to 6 months in hospital and then a further 12 months of Rehab. He has a young family and is a great bloke. He was an site to do some screeding. But you don’t know him so you dont care.

What I meant to say, but didn’t, was that I haven’t got any issue at all with the subbies, whoever they are. There was a false accusation made against me that I did. It was a bad choice of words on my part in reply. I shouldn’t have taken the bait.

To make it clear though, rest assured I don’t have a ‘don’t care’ attitude about anybody being injured at work especially when it was out of their control.

#102
Madashell3:47 pm, 17 Aug 10

“I’m just wondering what empathy towards same sex couples has to do with any of this discussion, Madashell?”

Yeah I was wondering that too? Arthur brought it up so I will defer to him on that point.
I think it was part of an ideological debate on whether human rights were more important than safty ordinances or some such thing. I’m not sure there is a right answer.

#103
Antagonist3:49 pm, 17 Aug 10

An episode of The Simpsons comes to mind here …
Bart: Milhouse, what happened?! You were supposed to be watching the factory!
Milhouse: I was watching. First it started to fall, then it fell.

First rule of management Mr Nohope – you are responsible for everything, and everything is your fault. I wonder how offensive he will find that statement ???

#104
Gungahlin Al4:00 pm, 17 Aug 10

Not going to pretend to any engineering expertise. But on the traffic issues, seems MANY people had the same idea about avoiding Flemington Rd this morning. The queue in Harrison trying to get out onto Horse Park Drive took 10 minutes (no traffic lights). But after that, the Federal Hwy was a ‘normal’ crappy 35 minute run in.

However, I was surprised to see all the southbound cars turning right onto Barton Hwy, because there was no signage to warn about the detour on the Federal Hwy southbound. There was a digital sign in the northbound direction though.

Can anyone report on using Flemington?

Interested to see for the second day running CT hasn’t seen fit to produce a map of alternate routes for their readers.

#105
Mothy4:43 pm, 17 Aug 10

Gungahlin Al said :

But on the traffic issues, seems MANY people had the same idea about avoiding Flemington Rd this morning. The queue in Harrison trying to get out onto Horse Park Drive took 10 minutes (no traffic lights). But after that, the Federal Hwy was a ‘normal’ crappy 35 minute run in.

I’m likely to regret this on my drive to work tomorrow…

…but can anyone tell me what all the hysteria about the traffic situation getting out of Gungahlin is? THE GDE is OPEN.

In fact, the drive in is smoother than before, since the usual logjam and backup that takes place from the merge on the Kaleen/North Lyneham side of the existing bridge has been removed (with the removal of City/Woden bound Barton Highway traffic).

This morning traffic was banked up on Gungahlin Drive from Palmerston to the lights at Mitchell (cemetery end) – i.e. it was the lights causing the backup, not some other bridge-collapse related obstruction or new flow of traffic. After that, it was the odd experience of doing 80kmph over the existing bridge, usually taken at 10-20kmph, past Kaleen and the AIS to the Belconnen Way off ramp.

Driving out of the city via the GDE in the afternoon though, well, I can’t comment. I avoided it as it’s the natural choice for those who would otherwise have gone down Northborne Ave to Barton Highway and out. Instead, I actually opted for Northbourne Ave!

#106
cranky4:55 pm, 17 Aug 10

Being a total cynic of anything Govco in this Territory, I could well imagine a hint being dropped to the AFP to set up RAPID ‘safety checks’ on the slow moving and congested alternate routes out of Gunners.

#107
H1NG05:26 pm, 17 Aug 10

The GDE is normally a waste of time. I live in Ngunnawal and work in Woden and make the trip every morning down Northbourne Ave because it is still quicker than the GDE. The run home isn’t as quick though so I turn up Barry Drive take the GDE from the Belconnen Way onwards.

This bridge collapse hasn’t changed my run to or from home. In fact, I think the traffic is slightly better.

#108
mutley5:44 pm, 17 Aug 10

Madashell said :

“I’m just wondering what empathy towards same sex couples has to do with any of this discussion, Madashell?”

Yeah I was wondering that too? Arthur brought it up so I will defer to him on that point.
I think it was part of an ideological debate on whether human rights were more important than safty ordinances or some such thing. I’m not sure there is a right answer.

I think you’ll find it was CraigT at #78 that brought it up. Nice way to derail a useful thread though

#109
Russ10:20 pm, 17 Aug 10

Just to clarify from the experts as to what *might* have happened.

From what I understand, there were a series of 760UBs (universal beams, or I beams) that spanned the gap over the road. These were there only as a temporary support for the concrete formwork, and the lengths of beam were joined with plates on the top and bottom flange and on the vertical web, bolted each side.

On top of these beams were some intermediate elements, then sheets of glossy black formply, then a criss-cross network of steel reinforcing bars along with large hollow steel tubes that would create hollow voids through the concrete span.

They began pouring concrete using that Schwing pump that seems to be marooned there, and at some point, the increasingly heavy “deck” of freshly poured concrete caused the supporting the I-beams to twist and rotate, losing their strength from the vertical part of the “I” and thus bending, collapsing the support structure and bringing everything down that was above it, including the poor workers.

So the critical failure was that the I-beams were able to twist when they should have been braced to prevent this?

Also, seeing that pump sitting there now – does anyone know whether the operator was able to flush the concrete out of the rams and piping?

#110
Arthur McKenzie10:39 pm, 18 Aug 10

Russ said :

So the critical failure was that the I-beams were able to twist when they should have been braced to prevent this?

It looked like that to me!

The only point I would differ on is the top flange splice plates and bolts were missing from the beams I saw. Somebody above mentioned they were replaced with a weld because the plates were removed to avoid fouling with the formwork. That would be consistent with what I saw.

#111
Madashell6:09 pm, 19 Aug 10

Yep I’d also say Russ is right so if that was one of your lighter 760UB’s with top loading and only partial lateral restraints at the supports (look at the ones still standing)then they’d only be good for about 20% of their fully restained capacity (assuming they span 11-13m). The other interesting point is that they are leaning in sympathy with the road camber which adds a P-Delta effect to the usual buckling phenomenom lowering the load capacity still further. The buckling equations in the code are independent of these torsional effects so some poor structural engineer is no doubt sitting around rederiving the code buckling equations from first principles to account for that effect.

I know you are probably all thinking that they could just build a finite element model (like on CSI) but that’s not really the same thing as the equations are trying to account for ‘out of straightness’ and residual stresses etc. You can also throw in a modecum of biaxial bending if you want to be really pandantic I guess, but the bottom line is that the lateral restraint was not as comprehensive as it should have been so it fell down. Everyone makes mistakes but when structural engineers make them they are very public affairs so I feel for the structural engineer in this case. Lesson learned for life I am sure but a dam hard way to learn it.

BTW someone was asking if the pump had concrete in the lines and I do not know but the hopper had been cleaned out so I expect that the answer is no.

#112
Russ8:15 pm, 19 Aug 10

Thanks for the responses Arthur and Madashell.

Madashell said :

The other interesting point is that they are leaning in sympathy with the road camber which adds a P-Delta effect to the usual buckling phenomenom lowering the load capacity still further.

So if I understand correctly, the middle beam would have been plumb, but beams either side out from the centre would be increasingly (slightly) out of vertical? What I don’t understand is where this camber derives from, given I’d have thought the underside of a bridge can be dead flat.

Or do you mean the camber being formed on the poured and screeded concrete imparts differing masses to each beam (ie. the load is heavier in the middle than the edge), causing them to respond in this manner?

#113
Madashell9:42 pm, 19 Aug 10

Russ said

“So if I understand correctly, the middle beam would have been plumb, but beams either side out from the centre would be increasingly (slightly) out of vertical? “

Road alignment over must be a sweeping bend because the deck has a oneway fall, underside has a parallel oneway fall and the beam supporting the ones that fell over has a parallel one way fall. So all the beams all lean in one direction. Might only be 2 or 3% but you can see the varying heights of the props on the adjacent spans. Probably not all that relevant in this case but sometimes such subtleties can be the straw that gave the camel an awful heria.

#114
Arthur McKenzie11:33 pm, 19 Aug 10

If you have a look using Google Earth you will see that the existing bridge and immediate approaches are straight and level so there would be no, or very little need for lateral camber of the bridge. Each sweeping bend ends well before the bridge abutments are reached. Lateral camber would be unnecessary to provide ‘extra traction’ for vehicles. It appears the existing bridge is fairly level longitudinally as well. Of course the bridge road surface (hotmix) would be ‘cambered’ to achieve adequate raindfall runoff and drainage. I doubt the new bridge would be any different.

What that means is the secondary effects referred to above would be negligible or non existent. P-delta effects are not a feature of flexural beam design in this case, they are primarily associated with axially loaded members such as columns in large heavily loaded sway resistant frames and are not relevant. The beams on the GDE falsework here would be required to carry negligible axial load. The only substantial source would be (non-existent vehicle braking forces or highly restrained temperature effects, equally non-existent) and secondary effects which would normally be carried by a bracing system. Effects due to imperfections are taken into account in the Perry-Robertson based design formulae in the steel structures code and are not directly taken into account in engineering calculations. Along with residual stresses in the steel these effects are irrelevant.

While not impossible it also is very unlikeley that a designer of this falsework would need to, or be bothered with wasting time, utilising finite element analysis. Either way the modelling method is of no consequence.

The failed falsework beams all tipped over to one and the same side because they were laterally unstable. The rest followed.

#115
Madashell10:15 am, 20 Aug 10

Fall is 3% oneway so no need to speculate futher on that point a) that’s how it looks b) the beams all fell in one direction c) (and most importantly)I know some people in low places at Roads ACT who have confirmed it.

Arthur says “P-delta effects are not a feature of flexural beam design in this case, they are primarily associated with axially loaded members such as columns in large heavily loaded sway resistant frames and are not relevant.”

Why the big deltas get all the big press when the little deltas can be just as important I’ll never know (Leonhard Euler would be most unimpressed). Firstly I’d suggest that P-Delta effects are relevant to all columns depending on exactly how you want to define your delta (could cite thousands of techical articles but I won’t). For what its worth a lateral buckling failure of a beam is directly analogous to a column failure in the sense that the compression flange is esentially failing by buckling sideways. As to whether P-delta may be relevant in this case. If you consider that the delta is the offset nature of the load to the neutral axis of the steel beam then I would suggest it is (although largely from an academic perspective).

The other technical point of interest is which beam has the heaviest load? Now intuitively many are going to say that that’s easy the ones under the voids have a lighter load (hmm maybe not). If you consider for a second the fluid nature of the concrete you might think no, wait a second the void tie downs will transfer uplift away from that area so they may in fact have the heaviest load.

By the time you have slept on it you might even think that depends on the slump of the concerete or the relative time to initial set, whether it is currently being vibrated, what temperature it is at now, what temperature was it batched at, whether there are any set retarders or superplasticisers in it or indeed who the Captain of Hawthorn is this year. Fortunately there is always some ironing out of this effect by the timber joists but my point is that like most things that look dead simple, they are not necessarily as simple as they first appear.

#116
shadow boxer3:35 pm, 20 Aug 10

So that’s 7 days now, surely enough time to minutely photograph and examine the mess, can we clean it up and re-open the road please

#117
Aeek4:08 pm, 20 Aug 10

Best thing for Glenoch for over a year.

#118
I-filed4:46 pm, 20 Aug 10

This is a worry. Seven years ago a colleague who was an engineer (albeit working in an IT job for the APS) observed some really dodgy practices going on with the construction of an office building in Allara St – one he was due to move into once completed. He raised his concerns with his supervisor – and was told to shut the **** up or risk his job. He shut up. I wish I had more detail. To this day I don’t know what the faults were, but I haven managed to avoid stepping inside that particular building myself!

#119
martyo7:20 pm, 20 Aug 10

flashback friday – must say I almost turned around at the prospect of this site on beclo way this afternoon…..http://farm5.static.flickr.com/4118/4910039224_fd2cec000c_b.jpg

#120
DJ9:31 pm, 20 Aug 10

I-filed said :

This is a worry. Seven years ago a colleague who was an engineer (albeit working in an IT job for the APS) observed some really dodgy practices going on with the construction of an office building in Allara St – one he was due to move into once completed. He raised his concerns with his supervisor – and was told to shut the **** up or risk his job. He shut up. I wish I had more detail. To this day I don’t know what the faults were, but I haven managed to avoid stepping inside that particular building myself!

Is this a “I once had a friend…” story? I prefer the Penthouse version that starts with “I never thought it would happen to me, but…”

Surely you can come up with some details about the ‘dodgy’ practices? Unless you can, it’s not really a worry is it?

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