Retrofit of the Hoan Bridge to Prevent Brittle Fracture

On December 13, 2000, two of the three girders of the Hoan Bridge in Milwaukee developed full depth brittle fractures leaving the span near collapse. Lichtenstein Consulting Engineers, in conjunction with Lehigh University and the Federal Highway Administration (FHWA), performed a forensic investigation of the failed span. The forensic investigation concluded that the cracking was due to brittle fracture and not related to fatigue. Lichtenstein performed a long-term retrofit design for the Hoan bridge that addressed the identified causes for the sudden brittle fracture and eliminated all fracture-prone details. A $7.8 million contract for the retrofit of all three-girder spans and the replacement of the demolished span was let in May 2001 and completed within five months. This paper will present an overview of the bridge failure, the forensic investigation findings and present the design of the emergency and permanent retrofits of the Hoan Bridge