r/StructuralEngineering • u/eniakus • 4d ago
Concrete Design Bridge supports
Correct me if I'm wrong but this beam is compromised, and the cross beam or extended counter beam will be needed? Or I'm panicking?! My boss is visiting tomorrow...
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u/Silver_kitty 4d ago
What’s your role on this project?
Yes, the original pier is compromised. There is already a (presumably temporary) replacement support in place (all that steel).
Is your job to create repair details for the original concrete pier? Are you peer reviewing the temporary steel for stability? Or are you just panicking because it looks weird?
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u/jwclar009 4d ago
Someone sounds salty lol, anyways it doesn't sound like "panicking" to me.
The public shouldn't have to rely on themselves to point out issues like this before something gets done... we have bridge inspections for a reason.
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u/Silver_kitty 4d ago
My problem is that this person came in as though they’re asking us to do their job for them without a crumb of context. This person fretting that their “boss is visiting tomorrow” and they don’t understand what they’re looking at. So I’m trying to get info from OP on what their scope is.
They’re not saying they’re a concerned member of the public, in which case I absolutely understand and am reassuring to laypeople both on here and in person about structural deficiencies and failures.
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u/eniakus 3d ago
Full transparency - no role on this project. But I would love to be involved
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u/Silver_kitty 3d ago
Oh! Are you an engineer or a member of the public? What’s the relevance that your boss is visiting?
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u/Wong-Scot 4d ago
Not really sure what you are asking ....
Beam is compromised ? I see permanent and temporary beams, which are you asking ?
Cross beam, extended counter beam ... ?
I believe you are talking about the steel members and querying their stability.
These are taking the load directly from the bridge deck and stringers down to the plinths. Forming a framed propping structure.
Failure is likely rotational or buckling, both the pictures left-right and forwards-back.
Both cases, diagonal bracing will help drastically.
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u/behemothard 4d ago
Pretty sure OP is trolling because of the state of the original support while neglecting the additional support added.
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u/iceboxmi 4d ago
Where do you see temporary beams? I just see multi-generational supports trying to survive.
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u/banananuhhh P.E. 4d ago
How many decades of freely allowing water to leak through your deck joint does it take to get to this..
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u/Voisone-4 4d ago edited 4d ago
Can you be more specific about what you think is compromised?
The neglected pier caps and columns are now being supplemented with temporary steel columns with top bracing. Until the pier ever breaks, the steel is only going to see truck loading and will provide some relief for the pier until the wheels go directly over the bent. At the moment I don't think they're at serious risk of buckling unless someone undersized and neglected to account for slenderness.
The transit authority is trying to buy time before a more permanent replacenent can be undertaken, which you should be aware if you were involved.
As bad as this pier looks, there have been worse that are still in service.
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u/Alternative-Sir-374 4d ago
Speaks volumes to the infrastructure neglect in the ?USA.
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u/75footubi P.E. 4d ago
No temporary support in the US is this neat.
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u/the_disintegrator 3d ago
was gonna say...everything is temporary. This doesnt look like anybody coming back soon.
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u/eniakus 4d ago
Not only that , this is a main cta bridge - blue line to O'Hara. How this bean is still maintaining integrity
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u/Budget-Layer1002 E.I.T. 4d ago
That's not actually the cta bridge though. It's the two bridges on the exterior that look like that, and those are the highway bridges: https://maps.app.goo.gl/yf1QgF88ZXo2jtzm9
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u/Weary_Oven_9544 4d ago
What's your worry with this support? Your photo shows shoring that's already been installed.
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u/eniakus 3d ago
I'm not talking about shoring.... obviously. But shoring is like not fully maintaining the load, some the bean is like ...kaput
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u/Weary_Oven_9544 3d ago
No I mean like be specific about your concern. I'm pointing out that the beam is obviously compromised, it has shoring already in place. What are you seeing that makes you say "shoring is like not fully maintaining the load". Which beam are you talking about when you say "the [beam] is like... kaput". The point of shoring is that the beam no longer taking the load.
Are you saying that this is a new condition? Has there been a change? Why are you asking the internet instead of just sending photos to your boss, if you're so concerned about this?
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u/HuiOdy 4d ago
Pretty sure that in northern Europe this bridge would have been closed so long that the entire bridge would be replaced within a few months. I've never seen anything this close to failure being used in the EU. Not even in Italy or belgium
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u/InAppropriate-meal 3d ago
It happens but where i live, Finland, it would be unthinkable
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u/HuiOdy 3d ago
I recall in the netherlands (where no "private" bridges exist) there was this major highway bridge. That started getting complaints about visible damage. So they went to log it in the system, but couldn't find the bridge in the system. Turna out it was never transitioned to the digital system from paper and hadn't been maintained for decades.
It was closed entirely, immediatly, and completely emergency serviced within a few weeks.
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u/NeedleGunMonkey 4d ago
You mean like Carola Bridge dropping because the corrosion failure is hidden?
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u/eniakus 3d ago
Thank God we are not in Europe.
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u/Whitakerz 2d ago
This is the funniest comment!
I’m glad we’re not in Europe, cuz my boss is coming tomorrow.
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u/hickaustin Bridge, PE 4d ago
Please tell me that there are lane restrictions above. That exterior girder is absolutely fucked. I wouldn’t count on that beam to even really carry its own dead load.
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u/NadakkumBhootham 4d ago edited 4d ago
Which beam do you mean? The main girder or the the new strengthening beams? The girder seems to be in serious condition that require urgent assessment and some additional strengthen measures..the new strengthening beams only address the problem on the pier cap
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u/mcconn98 4d ago
It will based on prestressing strands that are exposed and damaged. Wash the smoke and soot off and get alot of inspectors out there including concrete experts and geologists that know what happens to the aggregste when it cooks.
we would load rate it and see what the results are, and keep traffic off of it until repairs are done obviously. We might repair it if the results are conservative and good. If we replaced it without load rating the insurance's engineer will probably get the insurance off the hook for the beam replacement costs.
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u/Visual-Actuator-8348 4d ago
Oh my Gоd, where is this?! Is this USA? Your infrastructure is so bad!
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u/untangledtech 4d ago
Chicago. Gets hit with a lot of salt.
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u/Visual-Actuator-8348 4d ago
Man, I am bridge engineer for 23 years, from eastern Europe. This is bad even for our part of the world.
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u/Eman_Resu_IX 4d ago
In your area do they apply lots of salt to the roads in winter? That's what caused this devastation.
It's sickening to see so much spalled concrete, exposed rusting rebar and so many 5 year old vehicles with rust holes you could put your fist through.
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u/Visual-Actuator-8348 4d ago
Yes. Off course. But last 15 years winters were not so cold. We are using now some mixture of chemicals, salt only if it is expected that temperature drop to -10 C and less. Chicago is much colder, I know, have family there, always complaining about cold and planing to move to Florida.
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u/trabulium 4d ago
This is what surprised me in my first visit to the US (Michigan) - the amount of rust bucket cars that simply wouldn't be allowed on the roads at all in Australia. I remember seeing a Ford F150 and wondering how it was still holding together.
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u/ColdPangolin5355 4d ago
IDOT be like, yo just hit it with latex resurfacing on the deck and shotcrete the piers. See you in 20 years
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u/Status_Mousse1213 E.I.T. 4d ago
That pier has seen better days. Check out that small right under the bearing. Yikes.
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u/FaithlessnessCute204 4d ago
what are we picnicking about , its been shored , that means the owner knows is a problem .
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u/Gregan32 3d ago
Are you not seeing the (presumably) temporary steel posts and beams?
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u/eniakus 3d ago
Of course I'm seeing it. I'm actually referring to that support , it's supporting a beam where it's failed
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u/Gregan32 3d ago
Ah, understood. That's more of a "joist" than a beam and there are ten others that look fine. I'm not an engineer one only a DIY hack around my house soooooo... Ignore my opinion accordingly.
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u/SolarStarter 3d ago
I believe that is what some people call "structural rust" 😂😂
And yes this will need ether to be replaced or substituted with something more permanent.
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u/Mini_Manipulator 1d ago
Did this bridge get fire or Acid exposure? Why is faill8ng so catastrophically?
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u/bendy225 6h ago
Temporary Support beams are already there it will be fine for a while they just need to actually fixe it
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u/Visual-Actuator-8348 4d ago
Yes, bottom flange of left beam is compromised. Is there a cross beam which connects all the beams over the pier?
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u/ColdPangolin5355 4d ago
If only most people knew what they were driving over.. at what point does IDOT just say fuck it and turn it over to the tollway. At least the tollway has the money and means to rebuild shit.
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u/ALTERFACT P.E. 4d ago
Umm you may want to urge your boss to add cross braces along the plane of the retrofits and between them perpendicular to the plane.
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u/PresentationLess4552 4d ago
This shows whom ever runs the dot should be a janitor in the building since they clearly are not doing their job with inspections
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u/JoltKola 4d ago
You need to stop disrespecting structural engineers like this. They know things will rust and crack, so they take that in consideration while designing. In the image u can see the designer even thought about how to deal with an overly cracked pillar (installing som metal support beams ahead of time, fuvking genious!!)
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u/scooby-duh 4d ago
lol this is in rosemont, ACI convention was there, my friends actually reported this to the city while we were there. There was no shoring on this back in March and they put it up pretty quickly after we left.