how did tower 7 of the world trade center come down when fire cant melt steal?

Answer 1

by demolition like the WTC was it had minor fire damage and not thing hit it it was destoryed by demoliton

Answer 2

Typically fire in buildings reach about 1000-1100 Celsius regardless of the fuel. Steel doesn't melt until about 1500 Celsius. Jet fuel can burn adiabatically (without heat loss) at about 1600 C, but this only occurs in lab tests not in real fires but after the WTC collapsed some people in their ignorance out the two together and said steel melted. Steel starts losing strength and stiffness at 200 Celsius and has virtually none left at 900 Celsius. It has not melted but is "plastic " and will deform under any force.

WTC 7 collapsed well after the fire started. The building was unusual in that the foundation was built for a different building and the structural grid was different. There were massive trusses at about the third level to transfer loads from the upper structural grid to the foundation. It was thought that the fuel supply for emergency generators was ruptured close to one of these trusses and due to the way the system as designed the fuel kept flowing and the localised heating of the truss caused collapse. The truss was determinate (had no redundant members) and so failure of 1 member causes failure of the whole truss.

The building was also larger than the foundations and part of the structure above was cantilevered out from the foundations. This cantilever could possibly have been weakened when WTC1 and WTC2 collapsed causing vertical accelerations in the ground.

Some conspiracy theoreists will tell you it was demolished explosively by charges that were already laid but they really need to get a life.

Answer 3

All steel can melt by fire. That is how it is produced. All metals are produced this way.
That tower went down due to the instability in its foundation when the other two towers went down. Think about it, you had 2 building of over 100 stories each collapse within a couple of hundred feet of this building. The engineers never intended this to happen and therefore would not have designed a buildings foundation to withstand it.
No big conspiracy, just physics.

Answer 4

the fire didn't melt the steal and no one (other than conspiracy nuts) is trying to say that it did. building 7 was heavily damaged by the collapse of one of the two big towers. if you actually look at pictures and listen to audio form that day firefighters were saying how it was going to come down any second and they were frustrated because they weren't allowed to go into it and save people.

plus fire can soften steal to the point that it causes a collapse, think of spaghetti. suppose you built a tower of spaghetti and then i filled up a floor with water, the water wouldn't disintegrate the spaghetti, or burn it, it would just soften it and eventually your tower would collapse (sounds like a fun science experiment actually).

also fire can melt steal, you just have to get it hot enough. the average office fire does not get that hot though you are right, although most conspiracists tend to forget (or ignore) the fact that office fires can get up to 1100 degrees more than eough to soften steal.

umm anyways i've kinda rambled here, i hope you get my point though, take care.

Answer 5

If the heat from a fire is hot enough, then steel can definitely melt. Add the heat to structural damage from the other two towers collapsing, then it would be easy to see why 7 came down.

Answer 6

Anyone who builds small residential homes knows that it's safer to use wood than steel because steel will weaken and collapse long before wood will burn through in a fire. In a tall building you have to use steel, of course, but the problem of the steel softening and bending at relatively low temperatures is still a concern among builders. Take a piece of rebar and heat it to about a 1000 degrees F. You'll be able to bend it easily with your hands. Now imagine a beam holding up tons of concrete heated to that same temperature.
Oh, BTW, if you think that fire can't melt steel, hold a match to a piece of steel wool. It will burn and melt. Now go back and look at the inferno that was the WTC.

Answer 7

the element i hit upon maximum suspicious - extra so than the *seen* squib explosions; extra so than the workplaces being cleared out the weekend previous to the cave in; extra so than the thoughts of each of the firemen, policemen and witnesses (or maybe all of that in the time of all fairness persuasive) - is that the BBC *pronounced* that WTC 7 had collapsed mutually because it replaced into nevertheless standig interior the background. The stay satellite tv for pc feed conveniently vanished interior of a jiffy, and the BBC have because of the fact claimed they have lost the tape of it - "as a results of cock-up, no longer conspiracy." Is that even achieveable? thankfully others saved it and uploaded it, with the intention to all see it for ourselves. a great number of documetaries obtainable; a great number of rebuttals and a great number of scientists and chemical engineers on the two sides giving diametrically opposing evaluations on the comparable information... yet there is extremely no rebuttal for the actuality that the BBC knew it replaced into gonna cave in, an entire 20 minutes until eventually now it did. it is the main damning piece of evidence, because of the fact it replaced into so unintended. it is like somebody mis-study the memo, or possibly the ink on the fax have been given smudged, and that they made a enormous mistake by hazard, panicked, then compounded it by potential of attempting to cover all of it up. So, yeah, i do no longer think of it is so common as "Dubya is ebil and the gubmint doned it" yet imo they have been controlled demolitions.

Answer 8

When fire hits steel the steels modulus of elasticity increases , what that means is it becomes extremely ductile and it bends , steel is better than wood because steel may deform but in most cases still can hold the load. wood when burnt eventually collapses very quickly

Answer 9

aviation fire will do it involving magnisium, JP-5 or jet fuel it will go up to 3000 F. However, what brought the towers down was not the heat, but controlled demolition using explosives to detonate on specific areas of a building, so it can go down with the perfect symetry.

Answer 10

because it doesn't have to melt to be weakened so much by the high heat that it loses it's structural integrity. then it can't support the load weights it was designed for.

Answer 11

I figured it was due to the stress of surrounding buildings collapsing, along with being on fire....