1. THE WORST STRUCTURAL DISASTER IN U.S. HISTORY
Refs:
(1) Levy and Salvadori, “Why Buildings Fall Down”, Norton, 1992
(2) Petroski, “To Engineer is Human”, Vintage, 1992
(3)
Bring: rope
* KC Missouri Hyatt Regency: Opened July Poshest hotel in KC. Owned by Donald Hall (Hallmark Cards). 750 rooms, fine dining, the KC location for posh events
* Hotel in 3 sections:
(1) Room tower
(2) Function room block
(3) Atrium connection
3 open “skyways” (floors 2, 3, 4) traversed the atrium connecting the function rooms with the guest room tower.
Kansas City Hyatt Regency
7:05 PM, Friday July 17, 1981
114 dead, 200 injured
Source:

2. Source: Levi & Salvadori, “Why Buildings Fall Down”
* July 17: Ballroom dance people dancing to well-known local band
* People on all 3 balconies tapping their feet and swaying to the music
* A loud sound. Fourth-floor skyway started to fall, taking second-floor skyway with it. Concrete and steel crashed to the ground on the crowd gathered near the bar and sending shards of concrete flying up to 100 ft.
* What do you think happened?
* Suspects were: (1) frequency of foot tapping matched resonance of skyway, (2) poor materials or poor workmanship
* Do a “2 person on a rope” demo with 2 volunteers
* Answer: Design/build mismatch. A change was made during construction (approved by the designers) which caused the fatal crash

3. Skyway construction ROOF TRUSS GUEST TOWER FUNCTION BLOCK 4TH
FLOOR SKYWAY
HANGER
ROD
* Walkways are 120 ft long, in four 30 ft sections
* Sections are supported by transverse box beams
* Box beams are fixed to hanger rods anchored to roof truss
2ND FLOOR SKYWAY
BOX BEAM
Adapted from: Levi & Salvadori, “Why Buildings Fall Down”

4. * During construction, the design changed from one continuous rod to two rods.
* Original design called for a nut and washer 15 ft. up the 45 ft. hanger rod. Difficult to fabricate (thread whole rod or make threaded section larger diameter than the rest. Suggestion to change to a two rod design must have seemed reasonable.
* Other solutions: Use a sleeve nut to couple two rods. Use the box beam as the “sleeve”. Easy to see in hindsight!
Source: Levi & Salvadori, “Why Buildings Fall Down”

5. * Walkway #3 taken down. Now a single, second floor walkway supported by stout posts
* Turns out that original design would not have met code.
* Design engineering firm sued. Several designers lost their state licenses.
Source: Levi & Salvadori, “Why Buildings Fall Down”
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