Newsgroups: alt.folklore.urban From: ab401@freenet.carleton.ca (Paul Tomblin) Subject: Re: BRIDGES THAT RESONATE Date: Thu, 16 Jun 1994 12:28:36 GMT In a previous article, pdt@mundil.cs.mu.OZ.AU (Peter David THOMPSON) said: >charles.zucker@support.com writes: >>I'm doing this from memory - but there was a tragedy at, I believe, the >>Kansas City Hyatt Hotel on New Years' Eve sometime in the '80s. The >>concrete skybridge collapsed while dancers were rhythmically pounding >>their feet to "Satin Doll." Many died. > >I'm not interested in looking through some 10 years of Reader's Digests, >but it proved eventually to be a consequence of rather - inadequate - >design and/or construction. I seem to recall they used half the fastenings >they should have to support one skybridge - and then compounded the felony >by hanging a second from it. The safety factor was <1 for capacity crowds >on the bridges after this inspired work. Far be it for me to interject after ssuch a well researched followup, but here is basically what "Why Buildings Fall Down" (Matthys Levy and Mario Salvadori) (quoting directly from the National Bureau of Standards report on the accident) had to say about the Kansas City Hyatt Hotel disaster: "1. The walkways collapsed under loads *substantially less* than those specified by the Kansas City Bulding Code. 2. All the fourth-floor box beam-hander connections were candidates for initiation of walkway collapse. 3. The box beam-hanger rod connections, the fourth-floor-to-ceiling hanger rods, and the third-floor-walkway hanger rods did not satisfy the design provisions of the Kansas City Bulding Code. 4. The box beam-hanger to rods connections under the original hanger rod detail [design] (continuous rod) would not have satisfied the Kansas City Building Code. 5. Neither the quality of workmanship nor the materials used in the walkway system played a significant role in initiating the collapse" It goes on to say how the "the original design, though illegal, might have avoided the tragedy". Note; The original design had floor to ceiling continous rods holding up all the walkways. The contractor decided that it would be too hard to build them that way, so he suggested a design change in which the rods went to the upper walkway, then another set of rods went from the upper to the lower. The engineers did sign off that change. The failure seemed to occur because of the moment applied to the beams in the upper walkway because of the offset between the rods going up and the rods going down. Paul "The book actually has 10 pages on this particular disaster" Tomblin More info is available in (this courtesy of Mark Brader): The same disaster is discussed by Henry Petroski in more than one of his books, but particularly in "To Engineer is Human: The Role of Failure in Successful Design" (1985, St. Martin's Press, ISBN 0-312-80680-9). Petroski says that the original design had the rods running from the ceiling through the upper walkway (which was to be fastened to them by nuts on the rods at that point) and continuing through to the lower walkway (with more nuts at that point to support it), but not to the atrium floor below. In the revised design, the same design of connection was used between the upper rods and the upper walkway as on the lower walkway, but this now had to support twice the weight. Petroski does not mention the moment between the upward and downward rod connections, only the double force on the upward connection. This is a matter of detail; both books are in substantial agreement. (I've read both, though I don't remember that bit about the moment in the Levy and Salvadori book.)