The collapse of the hanging walkway at the Hyatt Regency Hotel in Kansas City in 1981, which killed 113 people and injured more than 200 others, was attributable to an erroneous connection detail. A detailed chronology of events contributing to this cataclysmic disaster has been widely documented (e.g., Pfatteicher, 2000). A defining feature of the hotel was its lobby. It featured a multistory atrium crossed with suspended concrete walkways on the second, third, and fourth levels. The fourth floor bridge was suspended directly over the second floor bridge, with the third floor walkway set off to the side several meters away from the other two. Difficulties during construction led to a subtle but flawed design change that doubled the load on the connection between the fourth floor and walkway support beams and the tie rods carrying the weight of both walkways. The engineers failed to review the initial design thoroughly, and accepted the contractors proposed plan without performing basic calculations that would have revealed its serious intrinsic flaws — in particular, the doubling of the load on the fourth-floor beams. The new design could not handle the dead load weight of the structure and the spectators standing on it. The connection failed and both walkways crashed one on top of the other and then into the lobby below. The two walkways were suspended from a set of steel tie rods, with the second floor walkway hanging directly underneath the fourth floor walkway. The walkway platform was supported on three cross-beams suspended by steel rods retained by nuts. The cross-beams were box beams made from C-channels welded toe-to-toe. The original design called for three pairs of rods running from the second floor all the way to the ceiling. Investigators determined that this design supported only 60% of the minimum load required by the building codes (Moncraz and Taylor, 2000).