Why does jet fuel melt steel beams but not paper passports?

8 Answers

  • 1 month ago
    Favourite answer

    Burning jet fuel burns paper passports, quickly. 

  • Anonymous
    1 month ago

    Real good, joseph. Except tower 7 was`nt hit by any aircraft. At all.

  • John
    Lv 7
    1 month ago

    Man yer dumb......

  • 1 month ago

    Take some math, statics, materials, and structures and you will be able to answer the stupidest most asked question on yahoo answers all by yourself.

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  • qrk
    Lv 7
    1 month ago

    Place a piece of steel in jet-A. It will not melt. If it did, we would have lots of diesel fuel spilling out of truck fuel tanks.

    Paper does not melt unless it's made from rice paper.

  • Joseph
    Lv 7
    1 month ago

    It does not melt steel.  The melted steel reference came from on scene reporters who used the phrase "twisted, melted steel" as a hyperbole to describe what they were seeing.  Many of them wouldn't recognize melted steel even if they stepped into it.  The conspiracy theory crowd then picked up on those words to add to their misunderstanding of the collapse process.

    All Mechanical, Civil and Structural Engineering students have to take a class called Strength of Materials.  About two weeks into the semester they learn how the columns buckle.  While I not going to derive the buckling formulas here, the gist of it is that the load the column can support is related to its free, unbraced length:  the longer the column, the less load it can carry.  Keep this bit of information in mind, I will come back to the column lengths a little later.  

    The steel framed buildings are typically built using columns throughout the building footprint that support the building and beams that brace the columns and support the floor slabs. The structure of the World Trade Center towers was different.  To create the column-free floor plans Leslie Robertson, the lead structural engineer for the buildings, designed a structural system of central concrete core and perimeter columns.  (This is why the World Trade Center windows were so narrow, by the way.)  Instead of solid I-beams lightweight trusses braced the columns and supported the floor slabs.

    When the planes hit the building they immediately cut a number of perimeter columns shifting the load they carried onto the ones that were still intact.  The crashes also started numerous fires.  

    Engineers design building with an assumption that a fire department will arrive promptly and will vigorously fight the fire.  It takes a fireman wearing full bunker gear, SCBA Pack, and carrying the firefighting tools and equipment a full minute to climb one floor.  Under the ideal circumstances it would have taken the firemen an hour an a half of climbing the stairs to reach the fire.  That's not taking into account the fatigue of climbing 80+ floors against the flow of people using the stairs to evacuate the building.  All the while the fire raged unchecked.

    In your ninth grade Physics class you may have learned that things expand when heated.  The floor trusses that braced the columns also tried to expand, but rigidly bolted at both ends they had no place to expand into but to buckle sideways.  When they buckled they no longer provided lateral bracing for the columns.  Remember what I said earlier about column free length and the load it can carry?

    As the column free length suddenly doubled or even tripled they buckled, shifting the load they carried to the remaining columns that were already overloaded.  One by one they started buckling in turn, starting a progressive collapse.  

    Source(s): Licensed Professional Engineer with over 31 years of heavy construction experience and witnessed the whole thing from the first plane crash to the final collapse in person, not on TV.
  • 1 month ago

    I didn't realize that Answers was recycling lame. questions from 5 years ago.

  • 1 month ago

    I dint get what your asking can you elaborate

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