Originally posted by: event8horizon
Originally posted by: TastesLikeChicken
Do you understand how they "estimated" those properties? It's not as if they flipped a coin or even simply pulled specifications from the drawings. They referred back to the original material certifications (which is what they mean by "contemporous documentation"), just as they did with the WTC 1 and WTC 2 steels (which were addtiionally tested physically to verify material composition).
One of the many jobs I've held was as a purchasing agent. Back in the 80s I bought raw materials to the tune of about $4 million dollars worth each year - steel, aluminum, copper, brass, bronze, and titanium as well as plastics and elastomers (rubber), and castings (sand, investment, and die). Every single shipment of raw materials was mandated to come with certificates of compliance (commonly called C of Cs) or material certifications that verified those materials complied with the specifications under which they were ordered. Whether we required C of Cs, which were a sort of testament provided by the distributor that referenced a material certification, or the actual material certs - where the materials were physically tested by an independent lab - every shipment of material came with documentation that was filed away.
The same thing is done when buildings are built. It's all part of the documentation required by code. That was no different 3+ decades ago when WTC 7 was built. For buildings like WTC 7 all raw material documentation for any of the load-bearing components must be material certs, no C of Cs. Physical samples from the production batches must be tested by independent labs. In addition, on large project like the WTC, materials are pulled from on-site and sent to a lab for testing, just to ensure that there's no shenanigans and that the material meets specification.
iow, in this case I don't think "estimated" means what you think it means. I know you're trying your best to cast doubts and the associated aspersions but it just doesn't work in this case.
your not telling me anything in that post.
again, from the fema report-
Several regions in the section of the beam shown in Figures C-1 and C-2 were examined to determine microstructural changes that occurred in the
A36 structural steel as a result of the events of September 11, 2001, and the subsequent fires. Although the exact location of this beam in the building was not known, the severe erosion found in several beams warranted further consideration. In this preliminary study, optical and scanning electron metallography techniques were used to examine the most severely eroded regions as exemplified in the metallurgical mount shown in Figure C-3. Evidence of a severe high temperature corrosion attack on the steel, including oxidation and sulfication with subsequent intragranular melting, was readily visible in the near-surface microstructure. A liquid eutectic mixture containing primarily iron, oxygen, and sulfur formed during this hot corrosion attack on the steel. This sulfur-rich liquid penetrated preferentially down grain boundaries of the steel, severely weakening the beam and making it susceptible to erosion. The eutectic temperature for this mixture strongly suggests that the temperatures in this region of the steel beam approached 1,000 °C (1,800 °F), which is substantially lower than would be expected for melting this steel.
Summary for Sample 1
The thinning of the steel occurred by a high-temperture corrosion due to a combination of oxidation and sulfidation.
Heating of the steel into a hot corrosive environment approaching 1,000 °C (1,800 °F) results in the formation of a eutectic mixture of iron, oxygen, and sulfur that liquefied the steel.
The sulfidation attack of steel grain boundaries accelerated the corrosion and erosion of the steel.
wouldnt it be good if nist studied this and found the cause so it wouldnt happen again. this is just one sample. there could have been more samples that had the same stuff going on with them.