On 2018-09-22 05:00, juan wrote:
On Mon, 17 Sep 2018 22:20:19 +0100 Peter Fairbrother <peter@tsto.co.uk> wrote:
WTC was rated for 3 hours major fire resistance.
Put that another way - *it was rated so that it _would_ collapse after 3 (or so) hours of major conflagration*.
It's in the design docs.
Where's your evidence for that claim Peter? WHERE are those 'design docs' ?
Please QUOTE-LINK the pertinent section of the 'design docs' that say 'rated for 3 hours of fire"
https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=861610 <blockquote> For this construction category, columns were required to have a 2 h rating as established by the Standard Fire Test (ASTM E 119); beams were required to have a 1½ h rating. The instructions to the bidders for the WTC 7 job were to bid on a 3 h rating for the columns and a 2 h rating for the metal deck and floor support steel, which corresponded to the more stringent fire resistance requirements for Type 1B (unsprinklered) construction. These ratings were to be achieved by application of Monokote MK-5, a gypsum-based SFRM that contained a vermiculite aggregate. According to the Underwriters Laboratories (UL) Fire Resistance Directory (1983), these ratings required a thickness of 22 mm (7/8 in.) of Monokote MK-5 to be applied to the heavy columns, 48 mm (1 7/8 in.) to be applied to the lighter columns, 13 mm (1/2 in.) to be applied to the beams, and 10 mm (3/8 in.) to be applied to the bottom of the metal deck. Private inspectors found that the applied SFRM thicknesses were consistent with these values</blockquote>