The Kemper Arena opened in 1973 as the new home of the Kansas City Kings basketball team. Because the roof was suspended from above, it featured uninterrupted sight lines. The innovative design earned the architect an Honor Award from the American Institute of Architects (AIA), and the AIA held its 1979 annual convention in Kansas City. Word of the collapse came to the AIA meetings opening banquet (Wearne 2000, pp. 26 -27).
The Kemper Arenas large flat roof, 97 by 108 m (324 by 360 ft.) was suspended on hangers from 3 large space frame cantilever trusses. The three trusses, each 16.5 m (54 ft) wide, were spaced 30 m (99 ft) apart and were made from pipe sections as large as 1.2 m (4 ft) in diameter (Levy and Salvadori, 1992, pp. 57 -67).
Each of the 42 hangers supporting the roof carried 622 kN (140 kips) in tension. The hangers used ASTM A490 high strength bolts, which are not recommended for variable or fatigue loads.
In order to reduce the stormwater runoff into the city storm sewers, the roof was designed to hold water as a temporary reservoir. The roof only had eight 130 mm (5 in) diameter drains. The local code actually required eight times as many. Once the water depth exceeded 50 mm (2 in) water could pour out over scuppers. This feature could obviously aggravate ponding.
At 6:45 pm a storm was dumping 108 mm (4 in) of rain per hour, along with wind gusting to 112 kph (70 mph). One arena employee present heard strange noises, followed by explosive bangs. He barely had time to flee. A portion of the roof approximately 60 by 65 m (200 by 215 ft) collapsed into the arena. The pressure wave from the falling roof segment blew out some of the arena walls (Levy and Salvadori, 1992, pp. 57-67).
A report prepared by Weidlinger Associates, working on behalf of a subcontractor, found
- The hangers had probably been weakened by fatigue cycles over the five years the arena had been open
- The roof was susceptible to ponding, and the wind pushed the water to pile up near the point of failure.
- It was necessary to analyze the roof in three dimensions, not just two, to determine the actual flexibility and ponding susceptibility of the roof
- One hanger fractured from the combined action of wind and water ponding weight
- Once one hanger failed, the roof had no redundancy. The other hangers could not carry the additional load, and several more failed.
The Kemper Arena collapse is discussed by Levy and Salvadori (1992, pp. 57-67) and also by Wearne (2000, pp. 25- 36). This case study is featured on the History Channel Modern Marvels More Engineering Disasters videotape/DVD.
This case study is discussed in Chapter 4 of the book Beyond Failure: Forensic Case Studies for Civil Engineers, Delatte, Norbert J., ASCE Press.
