Retrofit of Fatigue Cracks in Elevated Structures

Four elevated rail structures sequentially exhibited displacement-induced fatigue cracks between 1982 and 1991. Cost-effective retrofits were developed and implemented that have successfully controlled the problem. A case history of temporary and permanent retrofit solutions is presented. Through the use of instrumentation techniques, significant insight has been gained into fatigue cracking. A summary of the more-important findings of the programme, performed over a nine-year period, is also presented, along with recommendations for improving future designs.