Lafayette Building's top two floors subsiding?

[ghettopalmetto]

It's not a ridiculous comparison, daveinwindsor. Look at ACI 318, Chapter 11. Shear failure is shear failure is shear failure. The World Trade Center failed because the steel joist connections failed in shear, but its very possible to fail a concrete slab in shear at its columns. Slabs are designed to resist "static" loads; if a concrete slab from above falls onto the slab below, the magnitude of force upon impact is amplified. Either failure mechanism can lead to progressive collapse.

You may want to do a comprehensive review on building codes before you write so extemporaneously on them. You're spreading a LOT of misinformation. Are you an engineer?

I'm sure that whatever is causing this would have been noted when they did the asbestos abatement several months ago [[or did they only take bids for that?), and this may have been what we were all seeing in the news being called "instability" [[I think we all thought the reference was to the granite panels on the facade). Reporting this problem to the building's owner might actually result in its emergency demolition.

And on your grammatical point, I think that the generic "subside" is a good description. The geological "subsidence" that you mention is not a bad description for how it looks.

Asbestos contractors are not qualified to conduct structural condition assessments. They would not have noticed a damned thing.

But if you think the building is collapsing on its own, you'd rather risk lives of innocent people rather than notify the owner? How do you justify that?

You can use your term "subsidence" to mean whatever you want. I'm just telling you that to an engineer, it means something quite different than what you describe.

[rsa.313]

GP's right dave; your post is full of inaccuracies.

WTC did not collapse from poor and lax building codes or poor design. it failed structurally from impact of plane collisions and the subsequent fires. the collisions 1) weakened the structure, 2) dislodged fireproofing from ceilings, and 3) severed fire sprinklers. this allowed the subsequent fire to heat the steel to the point of elasticity, where it ultimately failed.

the empire state building is not a concrete structure. it is a steel structure that supports concrete slab floors. steel members [[columns and beams) are not encased in concrete.

steel does not reach the point of elasticity in a couple of minutes if drastically heated. the steel at the south tower withstood fires of several thousand degrees for almost an hour. the north tower made it almost two. the structure at the ESB would've suffered the same fate eventually.

building codes and standards were not better in 1931 than they were in the late 60's [[when the WTC was being designed). they continue to make codes more stringent, not less, throughout the years.

the stairs and elevators at WTC were encased in concrete.

the difference between the two is not quality control or times that they were built in. the difference is structural systems. ESB is a standard post and beam system laid out in a grid. this system offers a lot of redundancy and would allow sturtural failures to be localized. [however, if one section collapsed on 80, then that section above it would collapse and result in that section below it would collapse. no structure on earth is designed to withstand more than 5x what it's designed to hold initially.] WTC is a structural tube system. this system is very strong and allows for open floor plates. WTC would never have been built in the same system as the ESB. even if it was, that's no garauntee it would've stood without harm.

and, for the record, the lafayette building is not suffering from wear and tear, but neglect. if the structural failure [[if there is one) occured a floor or two down, you can bet that the sections above and below it would come tumbling down as well.

also for the record, the B-25 that crashed into the ESB was not carrying any ordinance. this instance, in fact, led the designers of the WTC to design the building withstand an impact from a 707 [[one of the largest jets at the time). the jets that impacted the WTC were 767, roughly 3 times larger than a B-25. also fully fueled with jet fuel, not aviation fuel for piston engines the B-25 would've used.

and, as far as your ascertation of the ESB being more expensive, it would cost $346351312.99 in today's dollars to build. when completed in 1972, the two main towers of WTC cost over $900 million. if we're generous, we could assume site preparation and foundation work was a third, and the two towers each cost a third. in today's dollars then, one tower would've cost $1527500757.30. granted economic conditions were vastly different, but just because you don't like the materials, doesn't mean that makes them "cheaper."

[davewindsor]

GP's right dave; your post is full of inaccuracies.

WTC did not collapse from poor and lax building codes or poor design. it failed structurally from impact of plane collisions and the subsequent fires. the collisions 1) weakened the structure, 2) dislodged fireproofing from ceilings, and 3) severed fire sprinklers. this allowed the subsequent fire to heat the steel to the point of elasticity, where it ultimately failed.

the empire state building is not a concrete structure. it is a steel structure that supports concrete slab floors. steel members [[columns and beams) are not encased in concrete.

steel does not reach the point of elasticity in a couple of minutes if drastically heated. the steel at the south tower withstood fires of several thousand degrees for almost an hour. the north tower made it almost two. the structure at the ESB would've suffered the same fate eventually.

building codes and standards were not better in 1931 than they were in the late 60's [[when the WTC was being designed). they continue to make codes more stringent, not less, throughout the years.

the stairs and elevators at WTC were encased in concrete.

the difference between the two is not quality control or times that they were built in. the difference is structural systems. ESB is a standard post and beam system laid out in a grid. this system offers a lot of redundancy and would allow sturtural failures to be localized. [however, if one section collapsed on 80, then that section above it would collapse and result in that section below it would collapse. no structure on earth is designed to withstand more than 5x what it's designed to hold initially.] WTC is a structural tube system. this system is very strong and allows for open floor plates. WTC would never have been built in the same system as the ESB. even if it was, that's no garauntee it would've stood without harm.

and, for the record, the lafayette building is not suffering from wear and tear, but neglect. if the structural failure [[if there is one) occured a floor or two down, you can bet that the sections above and below it would come tumbling down as well.

also for the record, the B-25 that crashed into the ESB was not carrying any ordinance. this instance, in fact, led the designers of the WTC to design the building withstand an impact from a 707 [[one of the largest jets at the time). the jets that impacted the WTC were 767, roughly 3 times larger than a B-25. also fully fueled with jet fuel, not aviation fuel for piston engines the B-25 would've used.

and, as far as your ascertation of the ESB being more expensive, it would cost $346351312.99 in today's dollars to build. when completed in 1972, the two main towers of WTC cost over $900 million. if we're generous, we could assume site preparation and foundation work was a third, and the two towers each cost a third. in today's dollars then, one tower would've cost $1527500757.30. granted economic conditions were vastly different, but just because you don't like the materials, doesn't mean that makes them "cheaper."

Yes, those newer building makes them "cheaper" in quality. If one of those planes hit the ESB, I guarantee it would still be there by the way it was built. From the earlier ESB crash, there was also structural damage and fire due to a direct hit by a plane and yet the fires were put out 40 minutes later and the unaffected floors of the building were open for business a day later. Yet, if we look closer to the WTC South Tower hit, we see the plane entered off center at an angle--missing the inner core, yet the tower goes down just like the North Tower, which was a direct hit. What about the 47 storey Tower 7 that also went down that day due to structural damage and fire, yet no plane hit the building? Tower 7 was the first skyscraper in history to collapse from a fire.

In 55 years as we've advanced with higher standards and more advanced fire prevention building codes and fire fighting equipment compared to 1945, how is it that Tower 7 falls like a tower of cards?

The ESB crash proved the superiority of the older construction methods. The outer walls were made of quarried limestone, the interior used grid of steel columns were fireproofed with concrete several inches thick, and they even had a concrete fire seperation between the units and the hallways. A quarried limestone exterior versus a modern glass exterior curtain wall? The structural columns of the WTC were tubes. WTC had skin of steel lattices proving 40% of structural support inside was core of steel columns. It was fireproofed with a thin layer of mineral fiber/cement that was sprayed on, which was easily dislodged.

The older constructed buildings proved their worth on 9/11--several older building
90 West, 130 Cedar, 140 West were all struck by debris from WTC collapsing, and, while heavily damaged, survived to be rehabilated. Yet, the more modern WTC 7 was also struck by debris suffered severe damage and the resulting fires caused its collapse. 90 West burned for 2 days, yet suffered little fire damage and survived. Talk about poor building standards compared to the older buildings.

Who cares about your funny numbers of how much it would cost to build and that they've found cheaper and unsafer ways to build highrises? It cost a fortune to build these old buildings back then too. The newer buildings will not stand up the test of time like older buildings such as the Lafayette. But, building a new old style building is not the point. The point is whether it's worthwhile to rehab these old buildings because half the job is already done as it's still standing. I'd gladly pay the enhanced price to live in a classic, more safer older building like the Lafayette if I was choosing between modern vs. old.

[Huggybear]

Asbestos contractors are not qualified to conduct structural condition assessments. They would not have noticed a damned thing.

But if you think the building is collapsing on its own, you'd rather risk lives of innocent people rather than notify the owner? How do you justify that?

You can use your term "subsidence" to mean whatever you want. I'm just telling you that to an engineer, it means something quite different than what you describe.

No one's saying that an asbestos contractor would know how to do a structural assessment like an engineer or building inspector would. But someone doing that work [[which is not exactly done overnight) would notice that there was debris everywhere or that there was water coming in through the roof. And it surely would have been spotted by any demo contractors estimating the project, since assessing the structure in at least a superficial way actually does fit their job classification.

To address your second point, I only said that it would not seem to be a good idea to report it to the building's owner, which has already announced an intent to demolish the building [[as they say in Buckaroo Bonzai) "real soon." If I saw an imminent danger to human life, I obviously would report it to Buildings and Safety or the emergency authorities. If you are able to decode the situation as something that needs serious attention immediately, you'd be a better person to report it than I would.

And I'm sorry I offended your sensibilities by using an everyday definition of the word "subside" rather than an engineering one. Does this bulletin board software support equations?