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# major Colombia bridge collapses during construction6

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## major Colombia bridge collapses during construction

(OP)
That's the country of Colombia.

A major bridge, 440 metres span, collapsed during construction. Seems to be a cable-stayed bridge with concrete towers and deck. Seems like one tower and span collapsed during construction, killing at least 10 workers.

http://www.msn.com/en-us/news/world/colombia-bridg...

A bit more detail and photos showing the scale of the bridge
https://www.nytimes.com/2018/01/16/world/americas/...

### RE: major Colombia bridge collapses during construction

(OP)
Those towers look "hell for stout" but the deck seems really thin. Not that this likely contributed to the collapse.

ETA: the thin deck caught my attention because the bridge was located in a narrow valley, a frequent source of higher winds, and bridges located therein are susceptible to vortex shedding loads. The deck of a cable stayed bridge is likely okay, although the issue has affected the stay cables on some such bridges.

### RE: major Colombia bridge collapses during construction

It looks like it came nearly straight down, which suggests to me that the bottom of one of the inverted V struts blew out. If it was a deck failure I'd expect the failure to be on one side and the unbalanced tension to pull the tower the other way.

I see that the roadway is off to one side with the top of the tower pointed the same way; this is also what I would expect if the strut on the other side failed first.

### RE: major Colombia bridge collapses during construction

Note to those who haven't opened links yet: pictures show dead people/person.

### RE: major Colombia bridge collapses during construction

Given that it failed when both half-spans were nearly complete, and cantilevered waaaay out, I'd wonder about a wind-induced lateral torsional resonance around the center of the tower. They do look stout, but not so much in torsion around their central vertical axis.

Mike Halloran
Pembroke Pines, FL, USA

### RE: major Colombia bridge collapses during construction

How did THAT bridge cost over 2 billion dollars?

Keith Cress
kcress - http://www.flaminsystems.com

### RE: major Colombia bridge collapses during construction

Yes, but the SF Bay Bridge is considerably wider with two decks (ergo: heavier) and is founded in the SF bay mud. (They're down in the old bay mud at least, but that still makes for a much more expensive foundation).

I don't know enough without research to comment authoritatively on lateral loads or labor/regulatory costs, but those must weigh in on the bay bridge's side too.

----
The name is a long story -- just call me Lo.

### RE: major Colombia bridge collapses during construction

Well, bear in mind that the SFBB was originally budgeted for $1B, so applying the same growth factor, this bridge was originally budgeted for around$300M

TTFN (ta ta for now)
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### RE: major Colombia bridge collapses during construction

I suspect that the location where the bridge was being constructed probably added significantly the cost of the project. After all, from the pictures, it looks like a rather mountainous region of a jungle, and unlike the San Fransisco Bay Bridge, there is no convenient body of water that could be used to easily transport building materials and construction cranes and such.

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### RE: major Colombia bridge collapses during construction

The Bay Bridge is also a self anchored suspension tower, not a traditional cable stayed bridge. This added significant construction costs for false work to support the bridge before it was completed.

### RE: major Colombia bridge collapses during construction

Yes, which is why it's similar to the Colombian bridge, although the suspension is much more similar to a conventional suspension. Note also, that this section is a single deck, not double.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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### RE: major Colombia bridge collapses during construction

Right, sorry, poor wording. Single deck, but two units wide (and do I mean wide.... something like 10 or 12 lanes total, plus shoulders and supporting the bike lane)

----
The name is a long story -- just call me Lo.

### RE: major Colombia bridge collapses during construction

Another video:

https://www.youtube.com/watch?v=QSU8GozlAKc

Maybe a foundation failure? Almost looks like the tower is trying to rotate to the left and away from this perspective. Hard to tell for sure. The strut clearly ruptures after the tower starts moving though.

IC

### RE: major Colombia bridge collapses during construction

The upstream (land-side) cables in the video all slacken nearly immediately. At the same time, the two V-beams relax (spread out) from each other as the top of the vertical column pulls down. Seems like the problem would be the vertical capacity of the split-Vee tower.

True, winds could have been present, but I see no twisting or jerking or flexing of the cables, bridge deck, or tower prior to the lacking of the cables.

### RE: major Colombia bridge collapses during construction

Too much slump in the concrete mix is a chronic issue in Central America. Lots of water makes the concrete easy to place. If you want a stiff mix, the locals know that you are doing it wrong. As soon as you turn your back they will "Do it right" and add water.
A wind gust may have been the trigger, but it looks as if everything went almost straight down.

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: major Colombia bridge collapses during construction

Looks to me that the back span on the failed section was a lot shorter than the one still standing...

Mike McCann, PE, SE (WA)

### RE: major Colombia bridge collapses during construction

It's not easy to see from that video which is though the best seen so far, but it looks to me like the first two cables just to the left as we look at it from the main tower start moving and flexing just before the rest. Would therefore look like the far strut of the V collapsed before anything else di, but it is not easy to see cause as opposed to consequence.

Very sudden catastrophic collapse though. you would have thought something would have started to crack or creak or moan at some point before the initial collapse.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

I am with LittleInch on this one, my take on the video (@ 0.25 speed on Youtube) is the same as his.

On the 'sudden failure' aspect, would that suggest the furthest fork failed in shear right where the /\ section joins the V of the fork?

That said, it looks as though there is a good amount of dust kicked off the inside of the furthest fork - which I suppose suggest the concrete has essentially 'exploded' under the compression load running around the inside of the fork at bridge deck level. Or perhaps it is the re-bar being ripped out of the concrete?

### RE: major Colombia bridge collapses during construction

I would expect the deck is being used to hold the legs of the tower together. To me, it appears the deck to tower joint failed on the far side first.

My first though was what an odd way to build a bridge support tower when I saw a picture of the standing structure.

### RE: major Colombia bridge collapses during construction

Maybe it wasn't supposed to be sorting on the support but suspended instead? Those cross wire connections in the upper bit of the V above the roadway also look rather weedy.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

Sure, because that crossmember wouldn't be able to hold the entire load of the bridge; it's purpose in life should only be to support the initial build of the deck, and as additional sections are built up, they're immediately supported by the cables. However, that crossmember is what keeps the legs from buckling out, and would be under tremendous tension, and I would have thought that it would be much thicker, specifically because it's under tension. Nevertheless, in the video, it looks more like the joint between the crossmember and the V-leg is what failed, and there might possibly be a design flaw in that joint.

TTFN (ta ta for now)
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### RE: major Colombia bridge collapses during construction

Counterfeit specifications on the supposedly high strength re-bar?

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: major Colombia bridge collapses during construction

If so, then the other side is suspect too...

Real can of worms here.

Mike McCann, PE, SE (WA)

### RE: major Colombia bridge collapses during construction

Well, the towers are absolutely under increasing compression loads from the top down to the V-split. Then, these compression loads are split in two, and become tension loads pulling the two V's further apart. Like two wishbones being pushed down from both ends, the middle of the wishbone is being pulled apart.

So, the weakest concrete and rebar at the top or bottom of the weakest joint of the four will fail first.

### RE: major Colombia bridge collapses during construction

The opposite of an arrow in a bow...

Mike McCann, PE, SE (WA)

### RE: major Colombia bridge collapses during construction

Did anyone else notice how the deck between the tower and land appears to support itself until the near side tower leg falls onto it? Temporary supports?

Also, was there a crane on the top of the tower? Did they do something wrong with the crane and twist the tower?

### RE: major Colombia bridge collapses during construction

I'm not sure, but I think there was a tower crane on either end, adjacent to the bridge tower, not on the bridge tower. Google up images, the one on the side that didn't collapse is pretty plain, the other end, I think had one, too, but it's not as clear.

### RE: major Colombia bridge collapses during construction

If you look at the tower that's still standing, there's a concrete diaphragm wall between the two inclined piers up to the deck level - e.g. see:
https://www.msn.com/en-us/news/world/colombia-brid...
This photo also suggests a beam or corbel on top of the diaphragm wall, which looks like it supports the roadway deck. Presumably, one of the functions of the diaphragm wall and / or the top beam is to resist the spreading force of the two piers?

It's hard to see this wall in the collapse video https://www.youtube.com/watch?v=QSU8GozlAKc, but if you look carefully , you can just about convince yourself that "something" explodes between the legs, and at 0'14", you can see a dark line down the centre of the far pier - is this where the diaphragm wall just pulled away?

Is this a case of inadequate horizontal tension capacity (either by poor design / detailing, or construction defect) of the diaphragm wall between the two inclined piers?

http://julianh72.blogspot.com

### RE: major Colombia bridge collapses during construction

Let's just hope that the Colombians are more inclined to share what happened than some of the other South American contries. I don't believe we ever got the story on the overpass which collapsed in Brazil just before the Olympics in 2016.

### RE: major Colombia bridge collapses during construction

Here are my observations from the posted videos.

There were tower cranes next to each tower. A red one next to the remaining tower and a blue one that is now in the rubble.

It appears to me the initial failure was a tension failure in the diaphragm under the deck that was holding the two V-struts together. The deck is entirely supported by cables so I doubt that thee was any deck loading onto this diaphragm or the beam at the top of the diaphragm.

In one picture there are the tops of what appear to be two towers that are visible behind the mountain in the background. There maybe another similar bridge on the other side of the mountain. Perhaps the $2 billion dollars is the cost of the whole road project and not just this one bridge. ### RE: major Colombia bridge collapses during construction Unfortunately I don't think the video actually captures the initial fault. Right at the start of the section with the collapse if you pause and look at the cables closet to the tower they are already not straight and not under tension so it look to me like the tower had already started moving at that point. I'm struck by a couple of things. One - how similar is this bridge? https://www.youtube.com/watch?v=ErBcdjgGtv8 The key difference is that the collapsed bridge is really a tower supported cable stay and is not symmetrical. I can only imagine that once the longer section exceeds the section length attached to the hillside, then as it extends outwards you constantly need to tighten up those three supporting cables anchored to the hillside to prevent any bending of the slim tower structure. I doubt that structure can withstand any bending load but how you accurately monitor the bending is maybe a key issue? Remember - More details = better answers Also: If you get a response it's polite to respond to it. ### RE: major Colombia bridge collapses during construction Interesting thought LittleInch. The land side of the bridge deck seems to stay in place long after the cables go slack and when the tower is falling the part extending into the air drops with the tower. Maybe the cables were tensioned improperly and bending the tower. But then, the Mexican bridge isn't symmetrical either. There are supports under the deck on one side of each tower with the deck only hanging from the cables on the other side. I don't believe the cable angle or lengths are symmetric either. ### RE: major Colombia bridge collapses during construction There is a cross beam just below the deck. Even if the deck is not fastened to the cross beam, it will be close and the cross beam will support the deck until it all comes unglued. Bill -------------------- "Why not the best?" Jimmy Carter ### RE: major Colombia bridge collapses during construction They were putting in a sewer line. Maybe they cut that main tension cross member to get the sewer line in place. ### RE: major Colombia bridge collapses during construction Here is some drone footage from August 2017 & a couple of good photos to give a better idea of the Before condition. Video: Link Photos: Link Link ### RE: major Colombia bridge collapses during construction I imagine someone is already comparing details of the Mexican bridge with those of the collapsed Colombian construction. On the video which LittleInch linked, it looks like there are stressbar anchorages on that tension tie, but there is nothing visible externally on the remaining Colombian tower. ### RE: major Colombia bridge collapses during construction from looking at the videos there does not appear to be a diaphragm wall below the cross bm on the two main towers while ,at least, one of the smaller towers does show this diaphragm wall..... ### RE: major Colombia bridge collapses during construction Bill - not if the crossbeam has broken away from the tower. But then, that "filler" inside the bottom part of the tower below the crossbeam might have stayed in place and been holding everything up. ### RE: major Colombia bridge collapses during construction SAIL3, Look at the photos which epoxybot linked 17:36. There is a wall there. Details unknown. There are/were only two towers, so am not sure what smaller towers you are talking about. ### RE: major Colombia bridge collapses during construction sorry, must have looked at the wrong video...yes there is indeed a diaphragm wall there.... ### RE: major Colombia bridge collapses during construction That's what I meant, Lionel. You said it better than I did. Bill -------------------- "Why not the best?" Jimmy Carter ### RE: major Colombia bridge collapses during construction I think the tower cranes were attached to the flat top of each of the two concrete towers. ### RE: major Colombia bridge collapses during construction When you watch the video of the collapse, it appears as though the first thing that happens it the cables on the far side relax and almost simultaneously the lower section of the far side of the tower begins to drop, the web explodes and the bridge deck beyond the tower drops but the bridge deck between the tower & the abutment remains stable until the tower completely fails. So it seems the deck between the tower & the abutment was shored. I wonder if much engineering went into the loads the shoring was placing on the slope above the tower's pile cap? ### RE: major Colombia bridge collapses during construction Epoxy bot. If you look at the photos and videos posted here and others linked when you watch you tube you can see the initial deck was built from both sides to the tower before the tower is completed and appear still be there just before the collapse. The blue tower Crambe was also attached to the tower by three ties. Makes you wonder if the installation engineering allowed for all these temporary but constantly changing loads. If some of the deck load was actually taken by the temporary supports and not the cables as the deck extends further out the stresses on the tower would be quite different to its final design load. Unless there is more footage we can't see I wonder if they will ever really understand what happened. Remember - More details = better answers Also: If you get a response it's polite to respond to it. ### RE: major Colombia bridge collapses during construction As others have said there was a horizontal 'slab' at the top of the diaphragm wall. However looking at this photo in particular Link, examine the reinforcement in the remains of the wall vs that in the 'tee' at the top of the wall on the right side. Notice what looks like essentially undamaged concrete on the right side as it lies? This suggests to me the tee might not have been adequately connected to the V columns, also of note is the large amount of reinforcement exposed in the diaphragm wall, but nothing similar visible in the tee (nothing exposed to the same extent at least). I'd expect quite a lot of reinforcement in the 'tee' if you consider a strut/tie model of what is going on. Distributed wall reinforcement won't achieve the same. Combined with what others are saying it may have simply unzipped at the pier/tee intersection due to insufficient tie reinforcement tying the two sides of the pier together. ### RE: major Colombia bridge collapses during construction I am far from a structural guy, but slow the youtube down and watch the progression of the area that I have circled. Was that a crack/fracture at the very first frame, or just some weird shadow. It seems to grow to me. You can see it maybe better at the 4 second mark as well. https://www.youtube.com/watch?v=QSU8GozlAKc ### RE: major Colombia bridge collapses during construction Possibly a tower crane brace where the tower crane has been removed? ### RE: major Colombia bridge collapses during construction #### Quote (Agent666) This suggests to me the tee might not have been adequately connected to the V columns, also of note is the large amount of reinforcement exposed in the diaphragm wall, but nothing similar visible in the tee (nothing exposed to the same extent at least). I'd expect quite a lot of reinforcement in the 'tee' if you consider a strut/tie model of what is going on. Distributed wall reinforcement won't achieve the same. Combined with what others are saying it may have simply unzipped at the pier/tee intersection due to insufficient tie reinforcement tying the two sides of the pier together. I agree with Agent666, and others, who have recognized the perceived 'weak link' in the delta-tower tie element. I did a bunch of 'construction' engineering for this bridge back in the early 1990's: I worked for a consulting engineering company who was engaged by the contractor to provide engineering to numerous aspects of the bridge construction - from delta tower jump forms, approach spans, staged construction analysis etc. The element that tied the sloping legs of the delta-towers (directly below the superstructure deck) was a significantly sized post-pensioned element, with a bunch of PT tendons. The photo below shows the stressing recesses where many PT tendon anchorages were accommodated and later concrete-patched. Delta-towers are very common for cable-stayed bridges. It would be interesting to see the engineering drawings of the tower for this Columbia bridge. ### RE: major Colombia bridge collapses during construction Spartan 5 - If you look at the linked photos in epoxybots post of 24 Jan 1735 you'll clearly see the tie struts to the blue tower crane. The idea or a post tensioned element clearly makes sense and makes you wonder why the web was being constructed in the first place. Most other towers like this don't seem to have it? Was it being used instead of a tensioned element at the bridge deck level? Interesting picture from 3Ddave if you look at the bottom of the concrete. The square base appears to be sitting on a circular shaft type foundation that is smaller than the base? Remember - More details = better answers Also: If you get a response it's polite to respond to it. ### RE: major Colombia bridge collapses during construction #### Quote (IRstuff) concrete and "tensioned element" cannot be equated. Sure it can. 'Precompress' the concrete to such a magnitude that, under the applied/sustained tension, there is still a resulting net compressive action. ### RE: major Colombia bridge collapses during construction #### Quote (3DDave) It's the same thing as in the image of the still-standing tower: https://www.msn.com/en-us/news/world/colombia-brid... I was looking more at the think horizontal line. There is a failure that progresses from there as the video advances. Or maybe not *shrug* I see those two nearest cables to the left slacking, then getting blown outward as debris from a compressive failure there shoot some debris outward. Maybe I'm just a grassy knoll kind of guy. I'll put together a slow animated gif together later. But meanwhile, go to the start of the 18 second mark and slow the youtube down with the settings to 0.25 speed. ### RE: major Colombia bridge collapses during construction When the tower legs start to spread, the top rigid joint has to break somewhere. I think that that crack is an effect rather than a cause. Bill -------------------- "Why not the best?" Jimmy Carter ### RE: major Colombia bridge collapses during construction The promised initial report mentioned in the link from j Stephen doesn't seem to have made it. Mind it didn't say which Jan 31 it was supposed to be issued. Nothing turns up in a search unless it's all in Spanish. Remember - More details = better answers Also: If you get a response it's polite to respond to it. ### RE: major Colombia bridge collapses during construction The Columbian government's National Agency of Infrastructure (ANI) released the following statements on 01/18/18 and 01/26/18. Translated it states: #### Quote (ANI Press release dated Jan 18 2018) Bogotá, Cundinamarca (@ANI_Colombia), January 18, 2018. - The commitment was established at the meeting led today by the president of the National Agency of Infrastructure (ANI), Dimitri Zaninovich, after the tour of supervision of the activities that are being carried out in the area of ​​the Chirajara viaduct. "The first and most important thing was to take stock of the attention to the victims. We also ask for permanent psychological and social support for all families at this time of so much pain. And finally, we have asked the Audit Office to provide us with a first report at the latest on January 31 to evaluate the main causes that explain the situation, "said Zaninovich. He added that only until the investigation is completed will the reality of what happened occur. "Until now we do not know the causes of this event and it is very premature to venture into different hypotheses," said Zaninovich, who was accompanied by civil engineer Jesus Manzo Suarez, Mexican expert in the construction of bridges and viaducts, and recognized world authority in the assembly of cable-stayed. The Mexican specialist will collaborate, together with more than 30 people of the Interventoría, in the collection of material and documentary analysis. At the same time, the Office of the Public Prosecutor of the Nation advances the collection of evidence at the scene and will isolate the area completely between one and two weeks. Local authorities asked the general public not to approach the area in the presence of unstable debris. At the evaluation meeting held on the viaduct, the ANI asked the Coviandes dealer to support the working conditions of more than 130 workers who had been working on the construction of this structure. With psychological support, Coviandes continues with the accompaniment of the families of the fatal victims. Of the nine injured, eight were discharged and only one remains in a clinic in Bogota, overcoming a mild trauma. The 459-meter-long viaduct - with three-span cable stayed system - is under construction and had not been put into operation. The ANI will inform in a timely manner the results of the investigations on this fact. Original Press Release 01/18/18 here. #### Quote (ANI Press Release dated Jan 26 2018) Bogotá, Cundinamarca (@ANI_Colombia), January 26, 2018. - A group of experts, all belonging to the American Concrete Institute (ACI ), will end Friday's two-day field visit to the Chirajara viaduct. to collect samples that - added to the review and analysis of documents, photos and videos - allow to establish the causes of the collapse of the western structure. The experts have been able to collate in the place of the facts information received of studies, designs and plans of construction, previous authorization of the authorities. The ACI is a technical, specialized entity with recognized experience and independence worldwide . "This group of experts, all with great international experience, will collaborate with the National Government to establish the causes of the collapse of one of the structures of the Chirajara viaduct," said the President of the National Infrastructure Agency (ANI), Dimitri Zaninovich. The scientific team is accompanied by representatives of the ANI and the Interventoría. Once the analysis is finished, it will deliver its conclusions to the ANI, in an estimated time no longer than a month. The specialists who are in the area belong to the Committee 133 of the ICA, dedicated to the study of the behavior of concrete (or concrete) structures during disasters. They are experts with doctorate in structures and with extensive international experience in the study, evaluation and diagnosis of failed or collapsed structures. Santiago Pujol , civil engineer from the National University of Colombia. PhD and professor at Purdue University (Indiana). Walter L. Huber Civil Engineering Research Award from the American Society of Civil Engineers and Chester Paul. Siess Award for Excellence in Structural Research from ACI. Michael E. Kreger , internationally recognized as a leader in reinforced concrete structures and earthquake engineering. Featured by the American Society of Civil Engineers TY Lin Award in 1991 and 2009 and Arthur J. Boase Award of the Concrete Research Council of the American Concrete Foundation in 2011. Arturo Schultz , professor of Civil Engineering at the University of Minnesota. BS summa cum laude in Civil Engineering from Southern Methodist University and MS and Ph.D. degrees in Civil Engineering from the University of Illinois at Urbana-Champaign. Collaborator of the Faculty with the Testing Laboratory of Multiaxial Subsets (MAST). The 459-meter-long viaduct over the Chirajara creek was under construction and had not been put into operation. The ANI will inform in a timely manner the results of the investigations on this unfortunate event. AMERICAN CONCRETE INSTITUTE (ACI) The American Concrete Institute (ACI) is a non-profit organization based in Farmington Hills, Michigan, United States, dedicated since 1904 to develop standards, standards and technical recommendations for reinforced concrete. Original Press Release 01/26/18 here.. Jan 31 has come and gone (as LitteInch stated) - no preliminary technical report/s released thus far, it seems. ### RE: major Colombia bridge collapses during construction Further digging...a report has been issued, as per this communique from Ministry of Transportation: #### Quote (Columbian Ministry of Transportation Feb 02 2018) 1. After receiving the first report of the intercontrol Interconcesiones on the causes that caused the collapse of the Chirajara viaduct, which identified imminent risks for users of the section adjacent to the collapsed infrastructure on the Bogota - Villavicencio road, at kilometer 62... Communique dated 02 02 18 Emphasis is mine. It appears the report has not been released to the public. ### RE: major Colombia bridge collapses during construction Well this is interesting...a snip from a tweet dated Jan 31 by Ministry of Transportation. #### Quote (Tweet dated 01 31 18) ...Consortium confirmed the imminent fall of the tower of the Chirajara viaduct that is still standing today and that is in an initial state of failure. Source And this also dated Jan 31: #### Quote (Marco A. Hinojosa, Supervision Interconcesiones) Although there are reinforcement techniques that could rescue the structure that remained standing, we recommend making a safe demolition, which avoids the risk for both people and the surrounding structures. Source ### RE: major Colombia bridge collapses during construction ...and from this Link: "...in the preliminary ruling of the collapse of the Chirajara bridge, a fault in the cross beam was identified". ### RE: major Colombia bridge collapses during construction Sounds like it is as we suspected. The tie beam is the weak link, but the whole design and construction require scrutiny. The demolition will be interesting. Drone emplaced explosives? Missile? ### RE: major Colombia bridge collapses during construction Here's a subscriber-only article, if anyone cares to dig into it (I haven't): https://www.bnamericas.com/en/news/infrastructure/... "Preliminary reports on the collapse of a suspension bridge on Colombia's Bogotá-Villavicencio highway point to an apparent design flaw in one..." ### RE: major Colombia bridge collapses during construction Not much more detail, but copied here for information. Preliminary reports on the collapse of a suspension bridge on Colombia's Bogotá-Villavicencio highway point to an apparent design flaw in one of the cross beams of the structure. The first study, done by the project's auditor Consorcio Interconcesiones with Mexican firm Mexpresa, recommended demolishing the section of the 459m structure that remained after the accident on January 15 that killed nine workers, the transport ministry said via its Twitter account. Minister Germán Cardona said that concessionaire Coviandes was responsible for the design of the bridge and it must decide if it will demolish the rest of the bridge or repair the structure. "This concessionaire had the obligation to deliver the bridge by June, so the respective sanctions will be applied, and in case the structure is rebuilt, no resources from the nation will be allocated to it," Cardona said via his office's Twitter account. The ministry also decided to close the road in order to prevent further accidents. Meanwhile, Coviandes announced that it will carry out an investigation of its own into accident, and that it has hired US firm Modjeski and Masters to do the studies, daily Portafolio reported. Work on the highway between capital Bogotá and the city of Villavicencio entails widening and maintaining a 45.5km stretch between El Tablón and Chirajara, including four tunnels and 15 viaducts and bridges. Investment in the stretch is put at 2tn pesos (US$700mn). The work is part of the government's 4G highways program.

If the government stands by its public statement, the company will still officially need to re-build the bridge at its own cost ( or its insurers).

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

Just for my own clarification...

This weakness in the currently-standing tower... does it only exist in the standing tower (i.e., may/may not have been caused by the other tower's collapse), or is it a design flaw that likely existed in the collapsed tower, as well (and possibly the cause)?

Dan - Owner
http://www.Hi-TecDesigns.com

### RE: major Colombia bridge collapses during construction

I didn't see it explicitly written down, but my take is that they have identified a design flaw applicable to both towers, hence why the other must also be demolished.

This would make me think the original designers made a mistake in either calculating the applied tension load in the cross beam, or a mistake detailing the connection of the diaphragm to sustain those loads.

I suppose, there could also be defective construction materials or a mistake made on site...

### RE: major Colombia bridge collapses during construction

It's interesting that when you look at other concrete delta towers, very few seem to have this diaphragm wall. It may have been required to reduce the potential for movement during an earthquake, but does seem to be a key difference between this bridge and others.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

No idea if I am right or not, but my gut tells me they were trying to 'distribute' the tension between the diaphragm and the tower legs over a longer length of the leg. Presumably this leads to a more economical design than would result if you designed for all of the tension at one point in leg as you would do with a tie beam.

The problem I see is that you will have more tension at the top of the diaphragm, with the tension reducing the further down the leg / diaphragm interface you move.

Perhaps they did not account for this properly (e.g. assumed the tension was constant at any point in the diaphragm / leg interface)? This would lead to local overstress at the top of the diaphragm and 'unzipping' of the diaphragm from the tower leg. To me, that is what the video seems to show just below the deck on the furthest leg.

Then again, I might be totally wrong!

### RE: major Colombia bridge collapses during construction

If you look at the picture of the presentation it seems to be talking about the beam (the red box). However maybe the beam was sized assuming some level of tension support from the web and if / when that failed then the tie beam wasn't man enough for the job?

Now which of the structural elements failed first isn't clear - beam or web?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

An expert says that the images, revealed by the CM & newscast, would indicate problems in the construction or design.

The Noticiero CM & revealed a video recorded by a security camera where the Chirajara bridge collapsed. In the circle it is observed how the bases of the structure yield.

Argelino Duran, President of the Colombian Society of Engineers, says that the video would reveal problems in the construction or in the design or in those two variables.

"The support column of the bridge that in that area where the road goes opens in two in a geometry as a diamond begins to move and begin to break the vertices of that rhombus and the diamond, which was elongated, ends up trying to become like square as it falls. Those columns that were part of the diamond did not support the effort that at that time they had to endure, "said Durán.

The engineer Duran, warned that it is necessary to thoroughly review the part of the viaduct that remained standing and does not rule out that it must be demolished.

QBE Seguros, the company that has the policy that protects the construction of the structure of the Chirajara bridge, assures that it will wait for the end of the investigation to respond.

"Our obligation is to investigate the events that occurred, we have a team of internal and external experts who are in the work reviewing what happened and trying to find the cause of the incident," says Antonio Sales, vice president of QBE Seguros.

However, the vice president of the insurer says that the work has several policies and that some of them must already be responding for the nine people who died and the eight who were injured.

"From the insurance point of view, different types of insurance operate here, for the victims are the personal accident policies, the group life policies and the ARL policies," adds Sales.

Only when the investigation is over can the operation be started to remove the debris from the bridge from the bottom of the canyon. For now the government estimates that the collapse of the bridge will delay the delivery of the dual carriageway to Llano for at least two years.

https://noticias.caracoltv.com/colombia/columnas-n...

Commission of international experts that analyzed the area warned that what affected the collapsed part could be replicated in the second.

The three American engineers members of the American Concrete Institute who visited the area concluded that the part of the bridge that is still standing presents a latent risk of collapse.

"They have been able to detect that the current bridge say that it is presenting a cracking that can make the collapse of this structure imminent," said Transport Minister Germán Cardona.

For this reason, the Ministry of Transportation informed the Coviandes concessionaire so that it immediately takes measures to guarantee the lives of the people who work in the area.

The president of the ANI explained that the North American experts have extensive experience in collapsed structures around the world and that they will deliver their report in one or two weeks.

https://noticias.caracoltv.com/colombia/tendria-qu...

Coviandes, concessionaire of the road between Bogotá and Villavicencio, signed a contract with the American firm Modjeski and Masters (M & M), to carry out the studies and analyzes that allow determining the possible causes that led to the collapse of stack B of the Chirajara bridge, which is part of the works of the double carriageway in the second section of this road corridor.

󰁒Do not rule out demolishing remaining section of Chirajara bridge

The chosen firm will be accompanied by the American Geotechnical Engineering Services (Ages), with the aim of deepening the geotechnical analysis.

According to Coviandes, after doing a study of 20 foreign firms, the selection of Modjeski and Masters was made not only taking into account their great experience in this type of research, but also to "guarantee total independence and transparency in their conclusions".

As part of the contract signed, this February 1 will arrive in the country, to move to the site of the incident, eight officials of the firm, who in addition to their studies of Master and PhD have extensive experience in design and analysis of structures, as well as research forensics of bridge collapse. "The team will be led by M & M vice president Thomas Murphy," added the concessionaire.

The specialists will evaluate the causes of the incident on the Chirajara bridge, study the current condition of the bridge foundations and make an exhaustive review of all the designs of the structure. "The activities include sampling of parts of the collapsed structure and quality verification tests, thorough review of the construction procedures, the results of the tests that served to verify the quality of the works and compliance with standards," added Coviandes.

http://www.eltiempo.com/economia/empresas/expertos...

### RE: major Colombia bridge collapses during construction

From Bridge Design & Engineering magazine's website:

#### Quote (BridgeWeb on 05 Feb 18)

The transverse slab contained tensioning strands, but the preliminary report by Mexpresa suggest the section did not contain reinforcement, which could have caused the section to fail...

...Consultants from Mexpresa said that they found no evidence of steel reinforcement, although they had not yet ascertained whether such reinforcement would have been necessary given the presence of the tensioning strands. The experts also highlighted the configuration of the steel stressing tendons, which connected the slab to the columns, where there was a greater number in a longitudinal direction than in the transversal.

Source: Link

### RE: major Colombia bridge collapses during construction

Thanks for that link, Ingenuity, but the part you quoted is gibberish, talking about the slab, not the tie beam.

### RE: major Colombia bridge collapses during construction

It looks at first glance like there was nowhere near enough cables to hold the legs from breaking. I interpret the crack in an area that should be under compression to support that conclusion.

### RE: major Colombia bridge collapses during construction

RandomTaskkk:

Thanks for posting that link.

Two images from that link that seem to support the more probable cause being failure of the tie-beam:

1] Exceptionally small quantity of post-tensioning within the tie-beam:

2] Significantly-sized vertical crack, that appears to be inboard of the tower column, within the web-diaphragm:

Also, it has been previously reported that similar cracks (and pending failure/collapse?) have been observed in the other tower - so this further suggests the tie-beam is the probable cause. However, granted, that all aspects need to be investigated, including foundations.

### RE: major Colombia bridge collapses during construction

I assume the crack shown IS in the existing/other tower.

### RE: major Colombia bridge collapses during construction

#### Quote (JStephen)

I assume the crack shown IS in the existing/other tower.

One would hope so - otherwise it was negligent to NOT report and act upon such a crack BEFORE the collapse.

### RE: major Colombia bridge collapses during construction

"One would hope so - otherwise it was negligent to NOT report and act upon such a crack BEFORE the collapse.

It would be oddly coincidental for the crack to be the existing tower and only to have appeared AFTER the collapse. I'm tempted to think that the cracks existed and were explained away by management intent on completing the bridge before the overrun got much worse.

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### RE: major Colombia bridge collapses during construction

In Engineers of Dreams a cantilever bridge is noted by on site people as having bent members over period of months. At first it was thought that they were arriving already bent, so the plan was to carefully note if any new members were bent before installation. It got bad enough that workers were refusing to show up.

The consulting engineer, who had initially declined to participate due to health reasons and remained in his home hundreds of miles away, was contacted multiple times and for reasons that are unclear found excuses. When the worker situation became critical he was contacted again. He eventually sent back word to cease work and vacate the bridge.

While those responsible for the site discussed what to do, the bridge collapsed, taking 86 workers with it and killing 75 of them.

I found another report, "Collapse of the Quebec Bridge, 1907.pdf" at
https:\\engagedscholarship.csuohio.edu/cgi/viewcontent.cgi?article=1020&context=encee_facpub

Similarly the Shuttle O-ring failure.

People get used to unexpected failure and start to ignore it because nothing bad has happened yet.

### RE: major Colombia bridge collapses during construction

The cable reinforcement looks sketchy to me; there appears to be as many as there are in my post-tensioned slab, which is not under anywhere near the same tension stresses.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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### RE: major Colombia bridge collapses during construction

#### Quote (IRstuff)

...there appears to be as many as there are in my post-tensioned slab...

And if you slab (on-grade) is with UNbonded PT, it is probably cracked too!

### RE: major Colombia bridge collapses during construction

Primer reporte Técnico de Mexpresa

First Report of Mexpresa.

There was only twelve 0.6" tendons in the tension direction and 122 tendons in transversal orientation.

### RE: major Colombia bridge collapses during construction

Thanks for that, I've run it through OCR and google translate to get a rough english version which you can sort of follow through and get the idea of whats going on. (quality of the scan is quite low though which impacts on the accuracy of this process)

I would hazard to guess that something must have seriously gone wrong with the design for the cross tie to have that low level of reinforcement. Guess time will tell why it made it through into the construction.

### RE: major Colombia bridge collapses during construction

Page 14;
The existing prestress in the braces is....................316.92 ton which is less than existing tension load of 375.48 ton.....
The remaining tower is cracking and has been declared in imminent danger of collapse.

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: major Colombia bridge collapses during construction

The cost of this collapsed bridge was only 25 millon dollars.
Can probably this low cost may one of the cause.
Constructors can't contract suitable proffesionals with these low costs?

### RE: major Colombia bridge collapses during construction

#### Quote (X4vier)

The cost of this collapsed bridge was only 25 millon dollars.

What is your source for the \$25M?

Others have previously posted that the bridge cost was in the billions.

### RE: major Colombia bridge collapses during construction

Well, the entire road construction cost was quoted as billions above, but 25 million for one bridge (even down south) seems much too low.

### RE: major Colombia bridge collapses during construction

El-puente-de-Chirajara-costo-72000-millones-de-pesos
That's around 25 millions!
Maybe the low cost can be a indirect cause of Collapse. Because contractor can see his profit reduced by hiring ideal staff.

### RE: major Colombia bridge collapses during construction

"Too cheap to be good" is a close relative of "too good to be true".

### RE: major Colombia bridge collapses during construction

The article also says the other structure is Ok!!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: major Colombia bridge collapses during construction

#### Quote (LittleInch)

The article also says the other structure is Ok!!
What other structure? The other tower?

### RE: major Colombia bridge collapses during construction

#### Quote (IRstuff)

The article is nearly 2 months old, so probably not a reliable source of engineering material anymore.

Why do you think is not reliable? It's a joke?

### RE: major Colombia bridge collapses during construction

The article is not reliable because it claims the other tower, now abandoned, was not compromised. In the time after the article it has been clearly determined that the remaining tower is also failing.

"Aunque es preciso esperar a que terminen las investigaciones, las autoridades señalaron que en principio la parte del puente que permanece en pie no debe estar afectada ya que es una estructura independiente."

Linking the failure to the low price is useless. It's not clear that some larger amount of money would have made up for what appears to be an engineering oversight. There have been a number of top-dollar projects that have suffered huge structural failures. They might have doubled the spending and still not have properly dealt with this failure mode.

### RE: major Colombia bridge collapses during construction

ACI COMMITTEE 133. Disaster Reconnaissance was in the site of collapse. The reports from this kind of events must be public to the students and engineers take the preventions in the future. Aren't they public ?

### RE: major Colombia bridge collapses during construction

Video:
Link

Bill
--------------------
"Why not the best?"
Jimmy Carter

### RE: major Colombia bridge collapses during construction

Did you notice the cable segments shooting off into the trees?

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### RE: major Colombia bridge collapses during construction

I'm a bit surprised it wasn't taken down with artillery instead of risking people going out to plant explosives, but the odds of missing the target is lower when the bombs are strapped to the target.

Any leads on how the design team for the bridge missed what seems like a fundamental free-body load calculation? Was the calc for inches and they used centimeters to order reinforcement?

### RE: major Colombia bridge collapses during construction

Artillery would be like almost literally using a cannon to kill a fly. There is a requirement for simultaneity and precision, which precludes artillery. The only thing that might have come close would be an M1A1, but you'd need several of them to get the specific spots, but the simultaneity is difficult to achieve with something that is manually fired.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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### RE: major Colombia bridge collapses during construction

IRstuff - why simultaneity? Just keep shoving rounds down range until it falls. It's not like they are trying to save surrounding structures in the fall zone.

### RE: major Colombia bridge collapses during construction

"It's not like they are trying to save surrounding structures in the fall zone."

There's a roadway right next to the pylon. I think the bridge was intended to be a bypass for the road, which is still active. They stopped the traffic during the demo. Screencap from the video:

TTFN (ta ta for now)
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### RE: major Colombia bridge collapses during construction

IRstuff - the road is not in the fall zone, but it is where artillery might hit, hence concern about missing. As a practical solution, just walk in dummy rounds of matching weight to avoid unexpected damage then send the explosive ones.

I am not sure it's even possible for the bridge to be forced to hit the road - to be tall enough the cables on the road side would have to be steeper than 45 degrees and they don't appear to be. Even to start would require simultaneously severing many cables on the valley side; pretty unlikely. Even the original failure didn't require simultaneous rupture; the rapid progressive failure was enough to drop the bridge nearly straight down and it doesn't look like the explosives did any better in minimizing the debris field.

### RE: major Colombia bridge collapses during construction

I don't know how things work in Colombia, but here in the US, demolition contractors don't normally have artillery pieces on hand and the US Army doesn't normally get involved in civilian demolition projects. So regardless of how practical it might be to blow stuff up with artillery, it generally isn't going to happen.

### RE: major Colombia bridge collapses during construction

#### Quote (OP)

I don't know how things work in Colombia, but here in the US, demolition contractors don't normally have artillery pieces on hand and the US Army doesn't normally get involved in civilian demolition projects.
After 15 years in Central America I have to say;
"You just can't say."
In one country, There was only one contractor in the country licensed to use explosives.
I would bet that he had access to military hardware, for a price.

Bill
--------------------
"Why not the best?"
Jimmy Carter

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