Where and what were you doing on 9/11/2001?

Reminds me of the guy who worked in a building yard. Every evening he left with his lunch box, tools and work clothes in a wheel barrow. Security regularly checked and verified all this stuff was his.

Turned out he was stealing wheel barrows
 
The_Doc_Man said:
OK, you KNOW it has to be asked... what did he do with a stolen bulldozer?
Click to expand...
He pushed stuff around at ground zero for a while and then left it there. Things were a little chaotic so I don't think anyone was really looking for it.

BTW, He had never driven one before either.
 
Last edited:
I've no idea. There's two things to this.
1) where were you when it was happening?
2) when did you hear about it?

Most American incidents happen at (UK) night time. So what day was it? And what time (UK) did it happen? To be honest, I don't remember. I suspect it made the papers here next day. I don't usually watch the TV news - too miserable.
Col
 
As to "when" - The terrorist attack happened starting at 08:46 Eastern Daylight Savings (USA) Time zone on Tuesday, Sept. 11, 2001. USA Eastern Daylight Savings time zone is 4 hours after Greenwich mean time, so that means it would have been just after Noon, London time (if I did that right.) It was televised as a network news event. We had a TV in our "break room" so someone heard the news bulletin almost immediately and called us in.

I heard about the first plane hitting the north tower (of the World Trade Center's two towers) within a few minutes of it actually happening. The second plane hit the South tower shortly thereafter, and a plane hit the Pentagon. A fourth plane crash-landed in Pennsylvania and was thought to have been aimed at either the Capitol building or the White House in Washington, DC. (Which of those two was the target is not clear.) The passengers overpowered the highjackers but could not safely land the plane.

Many of us have already answered the "where" part of your question. My business day started at 07:00 so I was in my place of work, as described in an earlier post.
 
BlueSpruce said:
Steel becomes very pliable when subjected to long_term intensive heat from burning jet fuel. One tower withstood the heat for almost an hour, the other lasted almost two hours. Another factor was where the impacts occurred. The lower the impact, the heavier the weight load. The new tower's upper structure was built using a cocoon design made of titanium alloy, which is supposed to withstand a commercial jet's impact. I periodically visited the construction site of the new tower and was amazed at how fast it was completed.
Click to expand...
Once mild steel reaches a cherry heat it will begin to be easier to work. Most forging can happen at between 1000ºc and 1200ºc, with melting occurring around 1400ºc. According to Isaac Newton, force increases by the square of the speed. So faster = more force. Strength of materials works in the same way. Doubling the thickness of a steel bar from 10mm to 20mm doesn't double its weight bearing qualities, or resistance to bending. They will increase by the square of the thickness

I understood that in order to reduce, or remove the need for changing lifts part way up the towers, a system of a main central core of beams was supported by joining it to the outer structure with a novel design. When the planes hit at the top floors the force and the heat weakened the outer supporting intermediate structure that was designed to support just one floor. When the weight of higher floors dropped to the ones below the combined weight was unsupportable. The cascade effect of floors dropping was inevitable causing the vertical collapse. That is my understanding of the collapsing towers.
It is unclear to me how any building could withstand the impact of a jet plane.
 
Cotswold said:
It is unclear to me how any building could withstand the impact of a jet plane.
Click to expand...
The titanium alloy cocoon in the Freedom Tower's upper floors will not resist a commercial jet's impact, but most likely prevents the domino effect collapsing the entire structure.
 
@BlueSpruce, I'm sorry in my opinion but you are wrong.
A floor in any building is designed to carry its own load as well as the estimated maximum load to be placed upon the floor. Any individual floor is not designed to carry the weight of two, or more loaded floors. Many buildings, those included, would no doubt have to carry the load of banks of computers as well as other plant and equipment, desks and people. If a floor is overloaded beyond its designed capacity it will fail. I would imagine that there would be maximum stated loadings that can be stored on floors in high rise buildings.

Even with titanium beams these principles apply. It may be that the section size of titanium beams is different to steel but they will not be so large as to allow double or higher weight supporting capabilities. Titanium and steel have different properties but titanium will only be used as a substitute where design dictates and costs allow.
In this scenario, from memory there were over 100 floors, so it is inconceivable that even one floor could support the weight of another dropping maybe ten or fifteen feet with the supporting steel, floor weight, walls, plant and equipment, plus people. The floor it drops onto is also bound to fail and so on. The only way to prevent collapse would be to have supporting walls, or propping from top to bottom which would probably be impractical and add too much costs.
 
Cotswold said:
@BlueSpruce, I'm sorry in my opinion but you are wrong.
A floor in any building is designed to carry its own load as well as the estimated maximum load to be placed upon the floor. Any individual floor is not designed to carry the weight of two, or more loaded floors. Many buildings, those included, would no doubt have to carry the load of banks of computers as well as other plant and equipment, desks and people. If a floor is overloaded beyond its designed capacity it will fail. I would imagine that there would be maximum stated loadings that can be stored on floors in high rise buildings.

Even with titanium beams these principles apply. It may be that the section size of titanium beams is different to steel but they will not be so large as to allow double or higher weight supporting capabilities. Titanium and steel have different properties but titanium will only be used as a substitute where design dictates and costs allow.
In this scenario, from memory there were over 100 floors, so it is inconceivable that even one floor could support the weight of another dropping maybe ten or fifteen feet with the supporting steel, floor weight, walls, plant and equipment, plus people. The floor it drops onto is also bound to fail and so on. The only way to prevent collapse would be to have supporting walls, or propping from top to bottom which would probably be impractical and add too much costs.
Click to expand...

Can the Freedom Tower Withstand a Plane Crash? The Science Behind Its Resilience

The Freedom Tower was built to withstand a plane crash, and has been tested to withstand impacts from commercial airliners. It is one of the safest buildings in the world, and is a symbol of resilience and strength.
flyfreshflight.com flyfreshflight.com
 
I totally forgot about the bombing at the WTC in 1993. I worked on 5th Ave. at the time.
 
Cotswold said:
Even with titanium beams these principles apply. It may be that the section size of titanium beams is different to steel but they will not be so large as to allow double or higher weight supporting capabilities.
Click to expand...
Titanium is stronger and lighter than Steel. Therefore it decreases the weight load and more resistant to collapse due to damage.
 
Last edited:
Stronger, lighter, better - all comparatives, not superlatives. Reduces the odds of collapses. Doesn't eliminate the possibility.
 
What was I doing on 9/11? I was doing a barn conversion to create a training centre for our rapidly expanding business.

I was there to review progress and answer ‘where do you want this’ type questions. The news came through the builders radios around 4pm.

Much of our business was with international companies and around 80% was serviced around the world in locations in the US, far east and Europe.

Two or three days later most of our clients cancelled future commitments due to the no fly situation. We lost around £400k of future revenue and regrettable the business couldn’t survive.
 
Wow ... that's sad, sorry you went through that . New businesses are delicate. Did you end up restarting the business in some way later?
 
CJ_London said:
Two or three days later most of our clients cancelled future commitments due to the no fly situation. We lost around £400k of future revenue and regrettable the business couldn’t survive.
Click to expand...
The world has never been the same after 9/11. It seems like everything steadily declined since then 🙁
 
Isaac said:
Did you end up restarting the business in some way later?
Click to expand...
No - I went into contracting, primarily identifying and filling in the financial holes between corporate systems typically using access. Took me 3 years to recover financially and went well - until Covid😀. Now I’m semi retired, working a couple of days a week for a few smaller clients
 
At the time of the 9/11 tragedy, I was a military contractor and was considered among the "essential personnel", We had masking requirements, working from home was a no-no unless you were sick AND had a hard-wired line for the connection. When COVID rolled around, they asked us to get shots when they became available, but business-wise? Not even the slightest slow-down for me or my colleagues. If anything, business picked up because more projects wanted our group to manage things. We had a good reputation after Katrina and rode that wave pretty much through my retirement. What they are doing now? Generally more of the same but, as usual, the Navy reorganized things again and I couldn't tell you the details.
 
Sigh
Any beam steel or titanium has s specific strength dependent on section size.
A 20" beam will be stronger than a 10" beam. To obtain the strength of a 20" beam in titanium will mean that it must have the same properties. It But it may well be, that a titanium beam has a smaller section size in certain cases. But it will probably be larger. (look at a titanium cycle and compare the tube sizes compared to a steel frame) Titanium is not less likely to collapse than steel due to its lighter weight. It depends upon the loading. Additionally, you cannot consider just the section size, there is also the support of the beam with its end connections.

Your theory about titanium being less likely to collapse is totally incorrect. I have already explained floor loads and the unusual building design. If steel is to be replaced by titanium, the titanium section will be selected on its ability to replace steel. The section size may well be less that the steel equivalent but improbable.

To reiterate, in the case in question, any section, steel or titanium will not be of sufficient strength to carry two or more loaded floors. If you doubt that, calculate the floor loading from multiple floors and work out the section size required to support 100 floors. I doubt that there will be a section size available to support even two floors as well as its own. Let alone the weight of the plane, fuel and passengers.
 
Cotswold said:
Sigh
Any beam steel or titanium has s specific strength dependent on section size.
A 20" beam will be stronger than a 10" beam. To obtain the strength of a 20" beam in titanium will mean that it must have the same properties. It But it may well be, that a titanium beam has a smaller section size in certain cases. But it will probably be larger. (look at a titanium cycle and compare the tube sizes compared to a steel frame) Titanium is not less likely to collapse than steel due to its lighter weight. It depends upon the loading. Additionally, you cannot consider just the section size, there is also the support of the beam with its end connections.

Your theory about titanium being less likely to collapse is totally incorrect. I have already explained floor loads and the unusual building design. If steel is to be replaced by titanium, the titanium section will be selected on its ability to replace steel. The section size may well be less that the steel equivalent but improbable.

To reiterate, in the case in question, any section, steel or titanium will not be of sufficient strength to carry two or more loaded floors. If you doubt that, calculate the floor loading from multiple floors and work out the section size required to support 100 floors. I doubt that there will be a section size available to support even two floors as well as its own. Let alone the weight of the plane, fuel and passenger
Click to expand...
If both Steel and Titanium beams have the same section sizes, the latter is not stronger? Then why would the architect choose to use Titanium beams? They also used lighter and stronger materials on the floors to reduce the weight load.
 
The same size of beam has to be larger in titanium. As an everyday reference I referred to a cycle frame which are often made in titanium but as I explained the tube section sizes has to be larger than a steel frame. You cannot have a frame in titanium with the same tube sizes as steel. Just as you cannot replace a steel beam of the same size as steel. It has to be larger.​

Titanium can be used as a structural material equivalent to steel beams, but it requires different manufacturing processes and has distinct performance characteristics. While titanium has a high strength-to-weight ratio—being approximately 45% lighter than steel while maintaining comparable strength—it is not as strong per unit volume as high-grade steel. This means that for the same cross-sectional area, a titanium beam would generally be weaker than a steel beam. However, due to its lower density, a titanium beam can be made lighter while still achieving similar strength, though it would need to be larger in cross-section to match the load-bearing capacity of a steel beam.

Titanium is difficult to work and drill, adding more expense. Generally, only governments and the offshore oil industry are the only ones who can afford to use them. In offshore oil there are long term savings with its resistance to corrosion and not needing paint protection.

Though it has yield strength comparable to structural steel, and having weight significantly lighter, its modulus of elasticity is only half of the steel. Requiring the section to be larger and deeper to match the same deflection limit if steel is used. Though this condition varies on the design approach of the structure itself., there generally isn’t a gain of using in replace of steel. Specially the larger difference in the cost of titanium vs steel. Plus the fact that steel is hot rolled into shape and titanium beams need to be welded from plates. Basically, instead of picking something from stock you need to create each one individually.

So basically, you're not often right but you are wrong again and I am not re-explaining this again.
 
You must log in or register to reply here.

Similar threads

P
What should Trump do after he wins?
2 3 4
Replies
67
Views
7,956
Pat Hartman
P
ShaneMan
What would you do, if you knew?
Replies
19
Views
3,572
Friday
Friday

Users who are viewing this thread

Total: 1 (members: 0, guests: 1)
Back
Top Bottom