the Illuminati

There nothing but a bunch of Ballwashin Bastards , they are already mass murderers imo. Sending all those troops to afgan & Iraq, for jack shit. That alone turns me against them.

i think the point is... what happened happened.

Us little people might never know the truth.

Majority of conspiracy theories are tosh tho.

NOT ALL

When someone who lectures politicians tells you something you tend to pay attention more than people waffling on message boards

it's like groundhog day on here - there wasn't 3 seperate breaches of the laws of physics - there was none!

i said this, i'm not a structural engineer, but my point was that these buildings were made in the 70's when building control wasn't an strict as it is now - so if those buildings were built today i'm sure they'd be built stronger. mainly probably cause of the health and safety culture we live in. they were so tall and narrow, they just never looked like they should have stood up in the first place nevermind being twatted by planes.

Nope the building codes which were vailid in the 1960's are still valid for steel buildings now, hell they haven't the allowables since before the 1960's, as I said steel design within allowables/yeild limits has been done so many times that it is generally just about recalculating stresses at connections, which in the 1960s would of been done by hand, where as now for a building of that size a small team could complete the structural design, the thing which is proves a problem now is fatigue and more inportantly fatigue life and how to cut the cost of steel with out reducing the life of the structure.

I won't derail this more with mindless work talk but all I am saying is that with out simulating every possibility and probably a full model of the entire building (not just steelwork) but bricks, windows, variation of weight due to amount of people fleeing, wind force/gust force at the time effects of heat on critical steel components.

Another thing to understand that steel production in the 60's was done roughly and the same QC we have not did not exist so you could have members which had many impurities.

Right I'll get back to work

Jet fuel burns at 800º to 1500ºF which melted steel tested by Popular Mechanics THEMSELVES up to 2750ºF.

3 building collapsed through steel weakening as a direct result of fire damage due to planes crashing into 2 of them.

Isn't that defying Physics?

You don't have to melt steel for it to fail, think of it like plasticine, when it is freezing cold it is hard to mould, when you heat it up it gets more plyable.

Same concept with steel, the average steel grade is s235J2G3 which has an operational temperature of room temperature, in offsore/naval engineering this is then varied using different grades of A (same thing as s235) and you begin to get temperature ranges for operational use, normally from -40 - + 40 above that you use more specilised alloys/cast materials.

So saying that steel won't be affected by 815 degrees C is a bit daft really.

Concrete cladded steel structure? Nothing taking down half of the structure inducing huge stress on the remaining structure? I don't know I haven't looked into that, neither have I really put any effort into looking at the failure method of the twin towers as on a night time I like to put my feet up and take my mind off what I did at work.

I am merely stating that steel will fail with that much heat put into it under extra load.

The steel was tested (beore it begun to degrade & melt) up to 2750ºF. So say I agree with you for a second & say the steel was weakend to the point where a floor or 2 collapsed under the pressure - Is that really enough to build up the Kintetic energy needed to pulversize 110 floors of 2 Sky Sraper buildings & 55 floors of WTC7 into it's own footprint at over 200mph?

Sorry the steel was tested at 2750 degrees F? (also your not american can you please use degrees C like the rest of the UK) Steel is never tested like that, you might be thinking it is a forged section edit: Forged at 2750) that is then given a material cert which gives proof stress/yield strength and composition of a test bit of material and at an operational temperature of room temperature.

I think you have gotten in to the pit fall of thinking that steel is homogenous w.r.t. temperature and that is not the case, I will have a quick look through my reference books in a sec and see if I can find the relationship between yeild stress and temperature, that will give you an indication how much of the actual strength of a UC/UB is lost when it is heated, and we are not even taking into account the buckling or warping factors which would come into play by the expanding connections/members.

As for the question about kinetic energy, with out know what actually failed as if I understand the way the WTC's were constructed it was around a main super structure, which if that failed then the towers would collapse.

The foot print thing is the only thing which throws me on this.

As I have said I am not debunking theories just trying to give this thread my little bit of knowledge in the field of structural engineering/design as I have been doing since leaving uni on various projects in civil,offshore and naval engineering.

This is just an extract from a journal so don't take it as gospel as I haven't read it fully, but if you look at the variation of Yield Stress on the Y Axis and Temp on the X you see a sharp drop from maximum to a lower value around 400 deg C.

http://resources.metapress.com/pdf-preview.axd?code=w828481328340q0l&size=largest

If NIST or Popular mechanics could give accounts as to why all 3 towers collapsed for the 1st time in Archetectural history due to fire damage id quite happily retract everything I choose to believe. Fact is they cant, well not enough to sway my from the fact that buildings dont fall in complete symmetry at freefall speed due to fires on a few floors.