Kemper Arena
* The Kemper Arena opened in 1973 as the new home of the Kansas 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. The Kemper Arenas large flat roof, 324 by 360 ft., was suspended on hangers from three large space frame cantilever trusses. The three trusses, each 54 ft. wide, were spaced 99 ft. apart and were made from pipe sections as large as 4 ft. in diameter.
* Each of the 42 hangers supporting the roof carried 140 kips in tension. The hangers used high strength bolts, which were 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 5 in. diameter drains. The local code actually required eight times as many. Once the water depth exceeded 2 in. water could pour out over scuppers. This feature could obviously aggravate ponding.
* At 6:45 pm a storm was dumping 4 in. of rain per hour, along with wind gusting to 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 200 by 215 ft. collapsed into the arena. The pressure wave from the falling roof segment blew out some of the arena walls. A consultants report found that 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. One hanger fractured from the combined action of the wind and water ponding weight. Once one hanger failed, the roof hade no redundancy. The other hangers could not carry the additional load, and several more failed.
NO COMMON SENSE
ANALYZE THE EXAMPLE
* Which supports and barriers were in play?
* What were the dynamics?
* Who, or what, won the Tug-of-War?
* Discuss the outcome with your friends and family.
* Use Post #4 as a reference for the dynamics, and the relationships, between supports and barriers.
