Our Train Station - Image

[Ian Rubie]

Another part of the story said "This is the sixth major bridge collapse in China since July 2011". I would not blame overloaded lorries.

 

[Crispin]

Of course it was the lorries. It would not have fallen down without them on. Clearly though, someone got it wrong. Either they skimped on something or the engineers did not build enough of a safety margin in. I would image you would have to cater for worst which would be a bridge jam packed with overloaded lorries.

Either that or they bought the bridge sections from China via ebay.

 

[AndrewT]

I read somewhere that china keeps their best quality stuff for themselves and the rest ends up on ebay !!

Buyers beware I think !!

 

[Rob]

So if it was overloading what would happen if there was a traffic jam with twice as many not overloaded lorries and 50 odd cars? The M4 flyover could cope fine with loads of stationary lorries and overloaded transits with the odd 10 axle mobile crane and those STGO lorries fully laden with crane weights and resurfacing machinery and did not fall down even though it was not structurally sound. Not buying the Chinese story at all.

 

[Crispin]

Anyone know what the safety factor standard is for the UK? How do they work it out?

 

[Graham]

Maximum weight continuously?
A column of 40 ton artic's, nose to tail?

On some night time runs down the motorways, there is almost never a car in sight.
If said artic's came up against an obstruction, they would all be brought to a halt ?

No idea really.

I think an artic is 45 foot long?
weighing 38 tonnes?

Gra.

 

[clivehorridge]

Road Structure calculations are rather complex, but you can bet your life that truck loadings would have little to do with a failure such as this. If you could imagine a section of road on a 40m bridge span carrying a traffic jam of say three trucks long 2 lanes overloaded to 50 tonnes each; 50 x 3 x 2 = 300 tonnes per span and the bridge deck weighing some 4,000 plus tonnes (guessing a bit here), the relative load of the trucks compared with the load of the deck itself, is not so significant.

The failure that appears to have occurred in the photo shows the deck intact, which suggests that the piling on which the foundations are supported failed.

Recently a residential high rise building "fell over" in China showing that the piled foundation supports were too small in section and too short for the ground conditions/loadings.
http://www.youtube.com/watch?feature=player_detailpage&v=pktM__i-8IQ

These are either design errors or the constructions are failing to comply with their designs. Either way disasters that should never happen, let alone 5 or six in the last 12 months!

 

[Crispin]

I'm no civil engineer but those pilings look like match sticks....

I suppose the possible weight on the bridge is small compared to the weight of the bridge so that bridge was destined to come down anyway.

Sent from my GT-P7510 using Tapatalk 2

 

[ram]

are the pilings supposed to be hollow

 

[Graham]

When I have passed similar supports, for roads and train track, they are always solid.

Well, the one's I have seen any way


Gra.

 

[clivehorridge]

There are always different and new techniques in construction but in my experience concrete piles are solid concrete with steel bar reinforcement running the length of the pile in a circular formation.

Piles transfer load from the structure down to a rock strata. If there is no rock strata to support the foundation, then piles long enough for the friction between the pile and the ground have to be installed. To get enough friction, normally piles would be between 600mm and 1080mm in diameter.

I've never seen tubular piles (but maybe the technology exists). Steel "H" girders or driven smaller diameter precast concrete piles can also be used.

 

[clivehorridge]

Maximum weight continuously?
A column of 40 ton artic's, nose to tail?

On some night time runs down the motorways, there is almost never a car in sight.
If said artic's came up against an obstruction, they would all be brought to a halt ?

No idea really.

I think an artic is 45 foot long?
weighing 38 tonnes?

Gra.

Most safety factors use a combination of static loads and dynamic loads. Static meaning the weight of the traffic and the deck(s) and dynamic meaning the forces applied to the deck by moving vehicles.

Joints between decks play a big part in this where the load is tranferred from span 1 to span 2 as a truck goes over the joint. If the end of span 1 is 5-10mm higher than span 2, then the downforce and the longitudinal forces of a 50 tonne truck travelling at 120 kph can be immense.

This normally would only raise questions about the strength of the deck bearings and the condition of anti-seismic devices, not as in this case, the integrity of the piers or the foundations.

Gross malpractice has occurred here, that's my bet and sadly, nobody will be found guilty. There will be a huge attempt to cover it up.

 

[Graham]

Gross malpractice has occurred here, that's my bet and sadly, nobody will be found guilty. There will be a huge attempt to cover it up.

.
I wouldn't bet on it at all.
There has been many investigations over the past few years that I have known about.
Some investigations going back many years to when the project was built.
Already, some body asse will be twitching.
"The ramp was designed by Harbin Municipal Engineering Design Institute, constructed by Fujian Jiaojian Group Engineer Co, Ltd. and overlooked by Heilongjiang Baixin Construction Engineering Supervision Co, Ltd.,"
Builders detail released already
The penalty for hiding away government construction money is death, as it is termed "financial fraud"
There has already been a few , , , , there was one just a few months ago.

Gra.
.

 

[BobMurphy]

Joints between decks play a big part in this where the load is tranferred from span 1 to span 2

My guess is that the decks are not attached to each other as there has to be an expansion joint between each of them.

Looking at the photos there doesn't appear to be any filler in the joint, we seem to use bitumen in the UK.

Maybe they got the expansion calculations wrong ???

I think the Chinese are on a rapid learning curve just as the UK was in the 19th century (Tay Bridge !) and with the same raw commercialism driving it. They will get there.

Bob.

 

[Crispin]

I think the Chinese are on a rapid learning curve just as the UK was in the 19th century (Tay Bridge !) and with the same raw commercialism driving it. They will get there.

Nicely put. Guess each country goes through it. America had a few interesting bridges. Galloping Gertie is the famous one and only a couple of years ago one collapsed.

 

[clivehorridge]

Gross malpractice has occurred here, that's my bet and sadly, nobody will be found guilty. There will be a huge attempt to cover it up.

I wouldn't bet on it at all.
There has been many investigations over the past few years that I have known about.
Some investigations going back many years to when the project was built.
Already, some body asse will be twitching.
The penalty for hiding away government construction money is death, as it is termed "financial fraud"
There has already been a few , , , , there was one just a few months ago.

Gra.
.

Clearly the truth should be established to prevent the same mistakes from being made again. I wouldn't advocate the 'death' penalty but that's China's judicial business.

Deck spans are rarely attached to each other although commonly they share supports. Expansion joints between the decks do nothing except maintain a continuous running surface for traffic. Expansion joints are rarely filled with anything, their job is to stay empty to allow adjacent slabs to expand and close-up the joint. They are often metallic 'combs' where each deck end 'comb' 'interlocks' with the other to save the wheels "bumping" over the gap.

Contraction joints (between slabs) use fillers, usually a bitumen based material and often silicone based in recent years, to stop the ingress of incompressible material when the slabs expand again (after contraction).

The failure here (just from looking at the photo) seems to be well below the deck, at support column foundation level or below. The deck has survived a huge impact (when it fell) that it wasn't designed to withstand, and appears to have survived in tact.

I hope some lessons are learned by this disaster to prevent others.

We've all made mistakes, UK; US; Japan... but we should all be sharing our knowledge and experience instead of each of us inventing the wheel individually. Luckily the UK hasn't had too many collapses (if any) but it has suffered premature bearing plinth failures on deck bearings (the support to the bearings between the underside of the deck and the supporting column crossbeams that the bearings are mounted on). This created deck level differences (the subject of my first message) which meant far higher impact loads as trucks dropped from one deck to the next (anyone who drove the M6 North of Birmingham in the late '80s early '90s will know what I'm talking about).

This excessive dynamic loading can cause premature failure of the deck itself, which is why the Ministry of Transport spent a fortune fixing the bearing plinths to save a disaster like this.

 

[Graham]

The deck has survived a huge impact (when it fell) that it wasn't designed to withstand, and appears to have survived in tact.

We've all made mistakes, UK; US; Japan... but we should all be sharing our knowledge and experience instead of each of us inventing the wheel individually. Luckily the UK hasn't had too many collapses (if any) but it has suffered premature bearing plinth failures on deck bearings (the support to the bearings between the underside of the deck and the supporting column crossbeams that the bearings are mounted on). This created deck level differences (the subject of my first message) which meant far higher impact loads as trucks dropped from one deck to the next (anyone who drove the M6 North of Birmingham in the late '80s early '90s will know what I'm talking about).

.
If I remember right, the old M6 over Thelwall was closed for a few years, just after they built the new M6 over Thelwall.
Some thing to do with the sliders which allow the decking to move?
Needed replacing?

Gra.

 

[clivehorridge]

Correct Gra.

It was what I was trying to explain, the 'sliders' being the bearings that support the deck on top of the columns. The bearings were OK, but the 'plinths' supporting the bearings were failing.

Mind, they were 25-30 years old...