Originally posted by KazetNagorra
Did you read that paper? It is not even about WTC tower 7, but about the two main towers. And it doesn't conclude that there was a conspiracy, nor that a fire couldn't have caused it to collapse of building 7.
A great number of buildings have collapsed after fires but there are not that many "skyscrapers" so what the authors wrote might be true depen ...[text shortened]... at the damage from the collapsing towers and the subsequent fires caused building 7 to collapse.
Yes I read the paper. I am quite aware that it does not explicitly analyze WTC 7. Are you aware that it is not solely a report on WTC, but instead is a generalized solution to the 1D Mechanics of Progressive Collapse (The sited failure mode of WTC 7 by NIST). And only sites the Twin Towers for Example. The following are the conditions for progressive collapse to be satisfied within the Example.
"Review of Causes of WTC Collapse
Although the structural damage inflicted by aircraft was severe, it
was only local. Without stripping of a significant portion of the
steel insulation during impact, the subsequent fire would likely
not have led to overall collapse Bažant and Zhou 2002a; NIST
2005. As generally accepted by the community of specialists in
structural mechanics and structural engineering though not by a
few outsiders claiming a conspiracy with planted explosives, the
failure scenario was as follows:
1. About 60% of the 60 columns of the impacted face of framed
tube and about 13% of the total of 287 columns were severed,
and many more were significantly deflected. This
caused stress redistribution, which significantly increased the
load of some columns, attaining or nearing the load capacity
for some of them.
2. Because a significant amount of steel insulation was stripped,
many structural steel members heated up to 600°C, as con-
firmed by annealing studies of steel debris NIST 2005 the
structural steel used loses about 20% of its yield strength
already at 300°C, and about 85% at 600°C NIST 2005;
and exhibits significant viscoplasticity, or creep, above
450°C e.g., Cottrell 1964, p. 299, especially in the columns
overstressed due to load redistribution; the press reports right
after September 11, 2001 indicating temperature in excess of
800°C, turned out to be groundless, but Bažant and Zhou’s
analysis did not depend on that.
3. Differential thermal expansion, combined with heat-induced
viscoplastic deformation, caused the floor trusses to sag. The
catenary action of the sagging trusses pulled many perimeter
columns inward by about 1 m, NIST 2005. The bowing of
these columns served as a huge imperfection inducing multistory
out-of-plane buckling of framed tube wall. The lateral
deflections of some columns due to aircraft impact, the differential
thermal expansion, and overstress due to load redistribution
also diminished buckling strength.
4. The combination of seven effects—1 Overstress of some
columns due to initial load redistribution; 2 overheating
due to loss of steel insulation; 3 drastic lowering of yield
limit and creep threshold by heat; 4 lateral deflections of
many columns due to thermal strains and sagging floor
trusses; 5 weakened lateral support due to reduced in-plane
stiffness of sagging floors; 6 multistory bowing of some
columns for which the critical load is an order of magnitude
less than it is for one-story buckling; and 7 local plastic
buckling of heated column webs—finally led to buckling of
columns Fig. 1b. As a result, the upper part of the tower
fell, with little resistance, through at least one floor height,
impacting the lower part of the tower. This triggered progressive
collapse because the kinetic energy of the falling upper
part exceeded by an order of magnitude the energy that
could be absorbed by limited plastic deformations and fracturing
in the lower part of the tower.
In broad terms, "
So...none of the
4 conditions are satisfied in WTC 7( a skyscraper in general), and not only that, but was designed by the same Engineer as the Twin Towers, and yet you have no modocom of doubt that the collapse of WTC 7 is justifiable, even though the author explicitly states what I highlighted in bold above under "Review of Causes of WTC Collapse"
A great number of buildings have collapsed after fires but there are not that many "skyscrapers" so what the authors wrote might be true depending on how strictly they define "skyscraper." By the way, the "journal of engineering mechanics" is a poorly rated journal (impact factor: 1.3) and getting a publication in this journal doesn't say much about the quality of the paper.
A little humility could have went a long way here. Below is the Authors Wikipedia Page ( where is yours?)
https://en.wikipedia.org/wiki/Zden%C4%9Bk_Ba%C5%BEant
I'll spotlight a particularly relevant piece of text from it. (Since you seem to have trouble thinking for yourself)
"Bažant, who is generally regarded as the world leader in research on scaling in the mechanics of solids,[1] is the author of six books dealing with concrete creep, stability of structures, fracture and size effect, inelastic analysis and scaling of structural strength. He is an Illinois registered Structural Engineer, and is one of the original top 100 ISI highly cited researchers in engineering (of all fields, worldwide). By June 2015, his H-index is 103, i10 is 496, and total citations 46,000 (on Google, minus self-citations).
Bažant, with his disciples, has made groundbreaking contributions to four areas of solid and structural mechanics"
This really puts a wrench into your, he could be just some fool that published a paper. For a PhD you seem to have a lot to learn yourself.