A Roof Praised as Innovative, Until a Storm Found Its Weak Point
Kemper Arena in Kansas City, completed in 1974, used an architecturally celebrated design: a large-span roof suspended from exterior space-frame trusses via hanger assemblies, rather than relying on internal columns to support the roof over the arena floor. In June 1979, during a severe thunderstorm, a large section of that roof collapsed onto the empty arena floor — fortunately with no fatalities, since the building was unoccupied at the time, but it became a widely studied case precisely because of what the failure revealed about combined load effects on an unusual structural system.
What Investigators Found
The failure was traced to a hanger rod connection assembly that failed under the combined effect of high wind loads and significant rainwater accumulation on the roof during the storm — the roof's drainage system wasn't able to shed the intense rainfall fast enough, and the resulting ponded water added substantial, unanticipated load at the same time the structure was also experiencing significant wind-induced cyclic loading on its connections. The specific connector detail that failed had not been fully evaluated for that combined, repeated loading scenario, and its failure initiated a progressive collapse of the roof section it supported.
Why This Case Changed How Roof Drainage and Connections Are Checked Together
The collapse became a significant reference point for the importance of checking ponding and drainage capacity as a genuine structural load case, not merely a plumbing or waterproofing consideration — particularly for large, relatively flat roof areas where drainage can't be assumed to keep pace with intense rainfall. It also reinforced the importance of evaluating critical connections for combined and cyclic loading scenarios specific to a structure's actual geometry and climate, rather than relying only on standard, generic connection design assumptions.
Quick FAQ
Was the roof's basic design concept considered flawed afterward?
The suspended, exterior-truss roof concept itself wasn't abandoned — the arena was rebuilt with a reinforced version of a similar system and remained in use for decades afterward; the lesson taken was about combined load evaluation and connection detailing, not about rejecting the overall structural concept.
Could better drainage design alone have prevented the collapse?
Improved drainage capacity would have reduced the ponding load component, but investigators specifically pointed to the connection's vulnerability under the combined wind and rain-load scenario — meaning both improved drainage and improved connection detailing were identified as contributing lessons, not just one or the other alone.
Final Thoughts
Kemper Arena's roof didn't fail because of wind alone or rain alone — it failed because a connection wasn't evaluated for what happens when both act together on an unusual structural system during a real storm, which is the kind of combined load case that's easy to underweight when checking each load individually looks fine.