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  1. 1Summary
  2. 2Licensing

Fse-restrained-thermal-expansion-v3.svg (SVG file, nominally 900 × 600 pixels, file size: 8 KB)

Summary

Walk-off of the girder at Column 79 of WTC 7: floor beams framing in from one side expand, shear the seat bolts and push the girder off its 11 in. (279 mm) bearing seat after 5.5 in. (140 mm). Based on McAllister et al. (2008), p. 527.

Original illustration for Restrained thermal expansion, level 4 Expert.

  • Source basis: McAllister et al. (2008), p. 527 (walk-off mechanism, 11 in. seat, 5.5 in., one-sided framing, no shear studs); p. 482 (seated connection model at Columns 79 and 81: bolt shear followed by walk-off); National Institute of Standards and Technology (2008), p. 22 (girder between Columns 79 and 44 pushed west on Floor 13)
  • Alt text: Plan of floor beams pushing a girder sideways from one side, and a section of the girder sliding off an 11 inch seat after 5.5 inches.

Licensing

New drawing by Fire Safety Academy. © Fire Safety Academy.

File history

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Date/TimeThumbnailDimensionsUserComment
current17:26, 2 November 2026Thumbnail for version as of 17:26, 2 November 2026900 × 600 (8 KB)Jan (talk | contribs)Watermark: Fire Safety Academy logo icon, 70 px, 45 % opacity

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