Understanding the Tragic Hyatt Regency Walkway Collapse

Understanding the Tragic Hyatt Regency Walkway Collapse

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On July 17th, 1981, two walkways collapsed within the Hyatt Regency Kansas City Hotel killing over 100 people and injuring over 200 more. These walkways plummeted and crashed on top of a tea dance held in the hotel’s lobby at the time. This was the deadliest structural collapse in U.S. history until the tragic events of the World Trade Centre some 20 years later.

Let’s have a look at what happened, shall we? A detailed analysis is out of the scope of this article, but if you are interested here is a great source.

Lobby view during the first day of investigation

[Image Source: Dr. Lee Lowery, Jr., P.E./Wikimedia Commons]

Countdown to disaster

The Hyatt Regency Kansas City Hotel’s construction began in May of 1978. The final 40-story building, despite some setbacks and delays opened in July of 1980. One event included the collapse of the atrium roof due to a failure of the connections at its northern end.

The lobby was one of the hotel’s defining features, which included a multi-story atrium spanned by elevated walkways suspended from the ceiling. These walkways were of steel, glass and concrete constructions that connected the second, third and fourth floors from north to south. Each walkway was around 37 meters long with each weighing in at around 29,000 kgs. Such was the design that the fourth level walkway was directly about the second level walkway.

Disaster strikes

1,600 people gathered on that night for a Tea Dance. At around 7 pm of that fateful night, the second-level walkway had about 40 people on it. The third and fourth-level walkways held about 16 and 20 people on each, respectively. Little did they know that some of them wouldn’t be going home.

Difficulties during construction resulted in an apparent design flaw change that double loaded the connection between the fourth-floor bridge with support beams and tie rods designed to hold the weight of it and any people present. As it turned out, sadly at the cost of lives, this new design was far from sufficient to hold the dead weight of the bridges, let alone additional weight from users.

The connections spectacularly failed, the fourth-floor and second-floor bridges plunged to the atrium’s floor. As the dust settled, piles of steel, concrete, and glass encased many bodies. Some would liken the scene to a war zone. It must have been a terrible sight.

[Image Source: Wikimedia Commons]

How could this have happened?

Three days after the disaster and rescue operation, Wayne G. Lischka, a structural engineer, began conducting a thorough investigation. He quickly discovered that the tie rod designs were to blame. He found a serious departure from the original design. Walkways were meant to be suspended from the atrium on continuous rods. This had been changed.

The manufacturer of these rods had concerns at the time. In their opinion, the need for the tie rods to be threaded along their entire length would be damaged during walkway hoisting. Two sets of tie rods were to be used. One for the fourth floor to atrium roof. The other for the second-floor walkway attachment to the fourth-floor walkway.

This was to prove fatal. This required the fourth-floor beams to support both the fourth-floor walkway but also the underlying second-floor walkway’s dead weight. A recipe for disaster. The box beams split along welds and the nuts supporting them slipped through the gap. The investigation further determined that poor communication between design teams and contractors was a large contributor to the failure.

Design changes, poor communication, poor or no calculations and general negligence all contributed to the collapse. Unbelievably, at times, designs’ confirmation occurred over the phone rather than checking the documentation. Shocking!

The final word

The fallout was pretty serious. Responsible engineers and firms had their licenses stripped, some went bankrupt. Compensation claims from the courts awarded victims around $140 Million dollars plus insurance payouts. This disaster remains a classic model for engineering models, ethics, and errors not to mention disaster management.

This should never have happened. Although plans had been changed, the original designs were far from perfect. According to the investigation, it would only have met 60% of the City’s prescribed building code requirements. Suffice to say that gross negligence on the part of team members led to a disaster that should never have happened. A real tragedy.

The Hotel has undergone various renovations since. Directly after the disaster, a single walkway was re-installed but this time supported by columns. The third floor has been left without a connecting bridge. Otherwise, the lobby generally retains its original design with the exception of its once hazardous walkways of course. The Hyatt Regency Hotel is now known as the Sheraton at Crown Centre.

Sources: EngineeringThinkReliability