Issued as an Interim Report on Life Expectancies of Highway Bridges --- Stress History Studies; Project IHR-301, Illinois Cooperative Highway Research Program

Increased volumes of truck traffic, pressure for increased axle and gross weight limits, and the use of new materials and structural details make the study of live-load stresses induced in bridges subjected to heavy truck traffic of increasing importance. The present study is directed to the collection, analysis, and interpretation of data on stresses at critical locations in bridges. It is focused on the development of a probabilistic technique for forecasting the stress range environment, and ultimately the mean fatigue life of the bridqe. The scope, physical arrangements - including a description of the test bridges, instrumentation and field test procedures, selected results, and an outline of methods for interpretation are described. This interim report emphasizes the presentation of data for stress range histograms and outlines the problems associated with the fitting probability density functions to histograms for use in the prediction of mean fatigue life. The data presentation includes results from four field tests. Selected truck data have also been included. The study makes use of a comprehensive, computer based, data acquisition, analysis and interpretation system.State of Illinois Department of TransportationU.S. Department of Transportation. Federal Highway AdministrationProject IHR-30