Rosemont Horizon Stadium
Roof Co l l apse Inves t i gat i on
On August 13, 1979, the partially completed glued-laminated timber arch roof of the Rosemont Horizon Stadium collapsed during construction, killing
five workers and injuring sixteen others. Laboratory testing and nonlinear computer analyses were performed by WJE to evaluate the stability of the roof
structure as influenced by the strength and stiffness of the decking and temporary bracing. WJE determined that the collapse was caused by inadequate
lateral bracing for wind and gravity loads.
WJE’s investigation of this failure was among the first to use nonlinear computer analyses to evaluate structural instability. The findings
underscored the importance of temporary bracing during the course of construction. The Rosemont Horizon Stadium collapse and similar
failures have led to much more stringent and specific code requirements for bracing of structures during construction.
Notes of Interest
• Four wire rope cables had been installed at the west
end of the stadium to resist eastward movement of the
roof structure during construction. No cable system was
installed to resist westward movement of the roof.
• The stadium was located directly under the flight path
for Runway 22R at O’Hare International Airport. One of the
early theories of the collapse was that it was triggered by a
plane or planes flying too low over the roof structure. Field
testing performed by WJE using pressure transducers
eventually disproved that theory.
• The City of Rosemont retainedWJE to investigate
the collapse and oversee the reconstruction of the roof
structure. With the help of WJE, the stadium opened
in May 1980.
WJE 50 Years