The horrifying collapse of the Surfside condo complex in Miami was almost certainly caused by corrosion of the steel rebar of the building's reinforced concrete structure. This is a headache for every civil engineer. It means bridges and buildings don't last as long as they should, and it means they need to add more concrete than is structurally necessary to protect the steel from rusting, which adds weight.
All of this means that lot of simple solutions to our transportation problems are prohibitively expensive. For example, many cities want to put lids over freeways. That sounds very simple, but the amount of material and all the labor and machinery needed makes it very expensive. The Klyde Warren Park in Dallas for example, cost $110 million for 5 acres (https://www.klydewarrenpark.org/about-the-park/our-story.html), that's $22 million per acre!
Urbanists are forever whining about the space we devote to parking lots and how pedestrians and cyclists are sidelined on streets. Architects going back to Da Vinci (https://www.da-vinci-inventions.com/ideal-city) have suggested solving this by vertically separating wheeled and foot traffic. Some places have done it, usually as part of lavishly subsidized mid century urban renewal projects, but in general, it's just too expensive to put buildings on stilts and then connect them by elevated walkways.
And highway engineers especially have their hands tied by the cost of grade separation. Turning congested at-grade intersections into free flowing interchanges is expensive, so instead they resort to adding more and more left turn lanes or using obnoxiously wide continuous flow intersections. Here in Massachusetts, we live with a high number of notoriously terrible cloverleaf interchanges because stacks are so expensive even if they are safer and can handle much more traffic.
Why oh why can't someone develop an inexpensive, strong, and corrosion resistant alternative to steel??
Quote from: kernals12 on August 08, 2021, 10:00:21 AM
Why oh why can't someone develop an inexpensive, strong, and corrosion resistant alternative to steel??
Because if it's corrosion resistant (this is what stainless steel is), it drives up cost. When you develop a material, you don't determine its price.
How long is something supposed to last?
Do I have this equation correct?
+ Steel sucks
+ Something about the Miami high rise collapse relates to highway infrastructure..
+ Urbanists bad.
+ Da Vinci
= Profit?
Because better materials are more expensive? If some wonder-steel that stays good for 1,000 years was developed and costed the same as the regular steel, every DOT would pounce on it. Building contractors, not so much, as that would significantly reduce their profits later on, since they would have very few projects to work on if buildings could stand flawlessly for 1,000 years.
You realize that at the vast majority of intersections where more than one left turn lane is necessary, surrounding development makes it impossible to build an interchange, correct?
Really I just have no idea what's going on here . . . what does the Surfside collapse have to do with it?
Da Vinci lived like 500 years ago so suggesting that his tactics are even a little bit relevant today is ridiculous.
You've really outdone yourself with this one.
I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.
But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).
The properties of steel and concrete are a known quantity. The quality of engineering work on a project is not. Don't even try to blame failures on the construction materials.
Quote from: Max Rockatansky on August 08, 2021, 10:52:30 AM
Do I have this equation correct?
+ Steel sucks
+ Something about the Miami high rise collapse relates to highway infrastructure..
+ Urbanists bad.
+ Da Vinci
= Profit?
This post made my day. The summary is accurate.
Quote from: kernals12 on August 08, 2021, 12:13:06 PM
Quote from: Max Rockatansky on August 08, 2021, 10:52:30 AM
Do I have this equation correct?
+ Steel sucks
+ Something about the Miami high rise collapse relates to highway infrastructure..
+ Urbanists bad.
+ Da Vinci
= Profit?
Do you just never make arguments in good faith?
Sure, just not when someone posts threads just sneak in jabs at things they have a hate boner for.
To that end (as someone already noted) there was a possibly interesting topic here that just ended up being buried by unnecessary ranting.
Also, I think stainless steel is softer than carbon steel.
Quote from: Max Rockatansky on August 08, 2021, 12:43:54 PM
Tell us, what are you actual qualifications and why should we listen to you?
Maybe car-centric "urbanist" ? :sombrero:
(And yes, urbanist is intentionally in quotations for a reason here).
Quote from: seicer on August 08, 2021, 11:07:44 AM
I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.
But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).
But a good material should be idiotproof
Quote from: kernals12 on August 08, 2021, 12:46:43 PM
And I keep abrest of technological developments so I know what's impossible today could be commonplace tomorrow.
Do you "keep abrest" like you have a job that deals with said technological developments, or do you just glance at news articles about them and come to a conclusion? Flying cars are a niche "technological development" too, why not mention it in your threads as much as magic pavement? It could be a better solution to your problems.
Quote from: SkyPesos on August 08, 2021, 12:51:14 PM
Quote from: kernals12 on August 08, 2021, 12:46:43 PM
And I keep abrest of technological developments so I know what's impossible today could be commonplace tomorrow.
Do you "keep abrest" like you have a job that deals with said technological developments, or do you just glance at news articles about them and come to a conclusion? Flying cars are a niche "technological development" too, why not mention it in your threads as much as magic pavement? It could be a better solution to your problems.
Actually they're not a niche development right now.
Quote from: kernals12 on August 08, 2021, 12:46:43 PM
Quote from: Max Rockatansky on August 08, 2021, 12:43:54 PM
Quote from: kernals12 on August 08, 2021, 12:25:02 PM
Quote from: Max Rockatansky on August 08, 2021, 12:23:12 PM
Quote from: kernals12 on August 08, 2021, 12:20:38 PM
Quote from: Max Rockatansky on August 08, 2021, 12:18:16 PM
Quote from: kernals12 on August 08, 2021, 12:13:06 PM
Quote from: Max Rockatansky on August 08, 2021, 10:52:30 AM
Do I have this equation correct?
+ Steel sucks
+ Something about the Miami high rise collapse relates to highway infrastructure..
+ Urbanists bad.
+ Da Vinci
= Profit?
Do you just never make arguments in good faith?
Sure, just not when someone posts threads just sneak in jabs at things they have a hate boner for.
To that end (as someone already noted) there was a possibly interesting topic here that just ended up being buried by unnecessary ranting.
You're the one with the hate boner. You've had it in for me since I started posting here.
Trigger warning: The Bay Area is a shithole.
Nah, more like a source of amusement as I sift through financial reports. Also, do you think that I have some sort particular affinity for the San Francisco Bay Area?
Your unhinged responses to my posts about the Bay Area maybe?
Unhinged? You're the one that constantly talks down to people who are actual engineers or have actually studied highway development like they are idiots. You also except to everyone to not challenge your hatred about particular areas, view points and ways people live that you don't agree with. Tell us, what are you actual qualifications and why should we listen to you? If you can't handle your views being challenged without acting like a baby (after seeing some your responses to me elsewhere) maybe you ought to quit public forums.
If you or thspfc are engineers, you aren't very good ones if you've never heard of the problems caused by rebar corrosion.
And I keep abrest of technological developments so I know what's impossible today could be commonplace tomorrow.
I'm not, that's why I listen to actual highway engineers and value their expert opinions. At best I might be at this point considered someone who has some actual historical perspective pertaining to highway development. From what you tell me it seems like you might be into selective reading and examine only sources that fit the narrative you are searching for.
Quote from: kernals12 on August 08, 2021, 12:55:44 PM
Quote from: SkyPesos on August 08, 2021, 12:51:14 PM
Quote from: kernals12 on August 08, 2021, 12:46:43 PM
And I keep abrest of technological developments so I know what's impossible today could be commonplace tomorrow.
Do you "keep abrest" like you have a job that deals with said technological developments, or do you just glance at news articles about them and come to a conclusion? Flying cars are a niche "technological development" too, why not mention it in your threads as much as magic pavement? It could be a better solution to your problems.
Actually they're not a niche development right now.
Flying cars or magic pavement/steel? Or both?
Quote from: kernals12 on August 08, 2021, 12:49:23 PM
But a good material should be idiotproof
So you're saying that anyone could take a sufficiently good material, throw it haphazardly around, and the structure should be sound?
Besides, as soon as you make something idiot-proof, someone comes up with a higher class of idiots.
I've made a similar thread about natural stone vs. concrete here (https://www.aaroads.com/forum/index.php?topic=24996.msg2416094#msg2416094). However, I listen to the responses.
There are alternatives, but a) they're more expensive than steel and b) concrete is very cheap, so if you get the same result with cheaper materials you will go that route every time. The only time you see non-steel is when there are significant constraints that won't let such a solution be feasible.
Quote from: kernals12 on August 08, 2021, 10:00:21 AM
The horrifying collapse of the Surfside condo complex in Miami was almost certainly caused by corrosion of the steel rebar of the building's reinforced concrete structure. This is a headache for every civil engineer. It means bridges and buildings don't last as long as they should, and it means they need to add more concrete than is structurally necessary to protect the steel from rusting, which adds weight.
All of this means that lot of simple solutions to our transportation problems are prohibitively expensive. For example, many cities want to put lids over freeways. That sounds very simple, but the amount of material and all the labor and machinery needed makes it very expensive. The Klyde Warren Park in Dallas for example, cost $110 million for 5 acres (https://www.klydewarrenpark.org/about-the-park/our-story.html), that's $22 million per acre!
Urbanists are forever whining about the space we devote to parking lots and how pedestrians and cyclists are sidelined on streets. Architects going back to Da Vinci (https://www.da-vinci-inventions.com/ideal-city) have suggested solving this by vertically separating wheeled and foot traffic. Some places have done it, usually as part of lavishly subsidized mid century urban renewal projects, but in general, it's just too expensive to put buildings on stilts and then connect them by elevated walkways.
And highway engineers especially have their hands tied by the cost of grade separation. Turning congested at-grade intersections into free flowing interchanges is expensive, so instead they resort to adding more and more left turn lanes or using obnoxiously wide continuous flow intersections. Here in Massachusetts, we live with a high number of notoriously terrible cloverleaf interchanges because stacks are so expensive even if they are safer and can handle much more traffic.
Why oh why can't someone develop an inexpensive, strong, and corrosion resistant alternative to steel??
Setting aside arguments about if it costs too much Money: It takes too much Time to make these Highest Quality Materials. The Construction Engineers need them now.
Quote from: kernals12 on August 08, 2021, 12:49:23 PM
But a good material should be idiotproof
Try to debate the same thing about Elevators. It needs to be designed Accurately And Sufficiently for people to be safe and for The Elevator to last for ever.
If some thing is idiot proof, there should not need to be any need to bolt it together, and some how magically stays together.
Even with all those Ancient Structures they made sure that every thing was designed properly so it would be built to last. Ancient Structures took very long time to finish. Nobody wants to wait that long.
The Surfside was designed so rapidly that they Violated Codes.
Quote from: kernals12 on August 08, 2021, 10:00:21 AM
The horrifying collapse of the Surfside condo complex in Miami was almost certainly caused by corrosion of the steel rebar of the building's reinforced concrete structure. This is a headache for every civil engineer. It means bridges and buildings don't last as long as they should, and it means they need to add more concrete than is structurally necessary to protect the steel from rusting, which adds weight.
Forgive me, but I need to correct a few misconceptions here. The bridge maintenance engineers that I know have a funny term for corrosion of imbedded rebar. They call it "rotting". In general, destructive corrosion comes from the contact or near contact of dissimilar (dis-similar) metals. When exposed to a corrosive basic or corrosive acidic solution, it creates a battery. In addition to electrons, molecules travel from one metal to the other and the first metal corrodes. When exposed to other sources of electrical activity, the corrosion can become catastrophic.
It would be wrong of me to say that mediocre materials have never caused catastrophic rebar failures. But I need to point out that the majority of these failures occur when metals outside the concrete structure are drilled into the concrete at multiple places, making contact with the rebar in a manner that the rebar becomes the shortest path for the return of stray electricity. (Note that if the electrical current is strong enough or the resistance is low enough, an electrical current will actually mitigate the corrosion process).
All that being said, I think the concerns raised by
kernals12 about mediocre construction materials have some merit and your conversation here should continue along those lines.
First, the study of why the Miami condo collapsed isn't finished. However, we do know in 2018 an inspection found numerous problems with the property which would have required up to $15M in repairs. The residents balked. They now have no building. It looks from initial reports that the collapse happened because poor maintenance and good old American cheapness.
I agree that we need improved construction materials. I don't think the Miami condo collapse is part of that discussion. It's tragic and stupid, but it's a shame that some people would use that tragedy as a starting point for a pet peeve.
Why we don't use cool materials? Because they are expensive.
And why they are expensive? Because there is little of them on Planet Earth.
Average concrete rebared bridge is built of iron (steel), calcium alumosilicate (concrete), silicon oxide (sand, granite), calcium carbonate (limestone). Aluminum oxide, calcium oxide and iron oxide get a honorable mention as part of gravel
Below is a chart showing element abundance in earth crust. See how it adds up?
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fblogs.agu.org%2Fmartianchronicles%2Ffiles%2F2012%2F05%2FElementsInEarthsCrust.gif&hash=ace4ebf94d0e2a285585072d64f26bba390632b7)
Bridges and skyscrapers would win big time from using high-end stainless, like 304 or 316 instead of steel. Single crystal nickel would work even better.
But do you see nickel and chromium in a chart above? Neither do I.
Quote from: kernals12 on August 08, 2021, 10:00:21 AM
The horrifying collapse of the Surfside condo complex in Miami was almost certainly caused by corrosion of the steel rebar of the building's reinforced concrete structure. This is a headache for every civil engineer. It means bridges and buildings don't last as long as they should, and it means they need to add more concrete than is structurally necessary to protect the steel from rusting, which adds weight.
A few comments:
1. I am not a civil or structural engineer.
2. Regarding steel (and in particular rebar and rebar mesh as used in concrete structures) I have in recent years seen something that would seem to increase the lifespan of rebar at fairly low cost - applying a coat of rubber or maybe rubberized latex compound to coat the steel and make it less vulnerable to corrosion. Seems like a fairly low-cost way to extend the life of the rebar (and thus the concrete structures where it is used).
3. While probably not relevant to the collapse of the condo building in Surfside, Florida (and I am not aware of there having been a formal determination as to what went so horribly wrong there), I do think that many of our bridges wear out faster than they should due to overweight (over on gross, over on axle tandems and sometimes over on single axles) commercial vehicles. In some states it seems that there is little or no weight enforcement done, perhaps to "save money." And we could be doing much more weight enforcement at lower cost with "virtual" weight enforcement, which costs much less to design and install when compared to conventional weigh/inspection stations.
What about that steel US Steel used in their Pittsburgh HQ? Supposedly it was supposed to rust on the outside to form a protective layer, like aluminum, and then be ok? Could something similar hold up in an ocean environment?
I think Kernals has a point here, yes the proximate cause of the collapse in Florida might have been poor maintenance, and possibly some problems with the initial construction, but it is worth considering that materials that are prone to failure without expensive upkeep may not be well suited to the job.
Part of the issue at Surfside was likely economics, more than engineering, as the peculiar legal and economic structure of a condo creates some bad incentives as far as upkeep is concerned.
Its also worth pointing out that the material used in most single family and smaller multi-family buildings is truly crap. 2x4 which are little better than sticks, drywall which is basically dust held between paper, shingles which are some kind of grit on an asphalt glue, the list goes on. If you look at what passes for construction materials in that market it is truly crap with a focus on minimizing short run costs with no longer term considerations.
You are referring to Corten steel. It does not hold up well in salty environments. If you ever travel north and check out what remains of Corten steel guardrails in New York State, or in areas where deicing agents are used, you'll see a pattern of extensive corrosion. I made a note here on AARoads some years ago where I had noted a lot of Corten guardrail along the highways in the Adirondacks had rusted away.
Then you have the Corten steel gantries (sign supports) in Charleston, West Virginia that have been mostly replaced with conventional galvanized gantries. Vibrations from traffic and salt spray caused extensive deterioration to the structures.
In general, rebar needs to be clean for it to be encased in concrete. It shouldn't be rusting (either as steel or as Corten which can take months to cure).
Quote from: cpzilliacus on August 08, 2021, 09:52:11 PM2. Regarding steel (and in particular rebar and rebar mesh as used in concrete structures) I have in recent years seen something that would seem to increase the lifespan of rebar at fairly low cost - applying a coat of rubber or maybe rubberized latex compound to coat the steel and make it less vulnerable to corrosion. Seems like a fairly low-cost way to extend the life of the rebar (and thus the concrete structures where it is used).
Epoxy-coated rebar actually has some vulnerabilities that can make it a poor choice, because any tear or puncture in the coating not only allows moisture into the rebar, it also traps that moisture against it, leading to very quick failure. It's been banned in Quebec, and several other provinces and states recommend against its use in environments where exposure to chlorides is expected.
Concrete is made of stuff like busted-up rocks, gypsum, and calcium oxide: really common stuff. Some new technology that hasn't been invented in the last–oh, you know, 2500 years–is bound to be more expensive by virtue of its using less commonly available materials.
Quote from: kphoger on August 09, 2021, 12:57:03 PM
Concrete is made of stuff like busted-up rocks, gypsum, and calcium oxide: really common stuff. Some new technology that hasn't been invented in the last–oh, you know, 2500 years–is bound to be more expensive by virtue of its using less commonly available materials.
Yes, but there may be some options even with cheap source materials
I am thinking single crystal aluminum oxide (ruby, sapphire) and amorphous - or again single crystal - quartz. These require high tech processing with lots of energy. But I can see them being the next-next-gen materials at some point.
Ruby rebar, fused silica fiber in good old cement... Nothing to corrode!
Well, for concrete you need specific grades of sand that's not as readability available. Conflicts have arisen over its scarcity: https://99percentinvisible.org/episode/built-on-sand/
Quote from: kernals12 on August 08, 2021, 12:49:23 PM
Quote from: seicer on August 08, 2021, 11:07:44 AM
I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.
But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).
But a good material should be idiotproof
Mother nature shows us a better material and humanity will engineer a bigger idiot in response. Always has, always will.
Quote from: kernals12 on August 08, 2021, 12:49:23 PM
Quote from: seicer on August 08, 2021, 11:07:44 AM
I mean, if this didn't have the rant about urbanists, it might have been a half-decent thread.
But construction materials don't have to "suck" if they are properly maintained. The corrosion that you saw in the condos was the direct result of bad design and engineering that led to water intrusion over the course of decades into the structural elements of the tower. For bridges, corrosion is the byproduct of the misapplication or overapplication of salt and the ill-maintenance of the structures to withstand the intrusion (i.e. being diligent in sealing the cracks and painting the surface). For highways, it's often because of value engineering the construction to the point that pavements only last 20 years without needing major rehabilitation. Or worse, needing rehabilitation off-the-bat (i.e. US 35 in West Virginia, King Coal Highway near Williamson).
But a good material should be idiotproof
This statement makes no sense.
an idiot proof material has never met a concrete mixing/asphalt plant i am afraid to say