Load model for bridge system reliability

Efficient evaluation of existing bridges requires knowledge of the load and resistance parameters. This paper concerns the development of a data base for load modeling using weigh-in-motion (WIM) technology. Presented are results of steel highway girder bridge testing using WIM and a strain data acquisition system. The ten girder, three simple span, two lane steel girder bridge is instrumented in its 33′- 6″ entry span for all data collection. The bridge is located on US23 which is a major route between Detroit, Michigan and Toledo, Ohio with no weigh station on the route. Vehicle weight statistics are collected simultaneously with strain data. Distribution functions are generated for gross vehicle weight (GVW) and measured girder strains allowing an analysis and comparison of the theoretical stress spectra based on WIM data to the actual measured stress spectra experienced by the bridge girders. Girder response to heavy vehicle multiple presence is presented as well as lateral load distribution functions and live load fatigue spectra for the girders. From these statistics conclusions are drawn regarding stress histories of the girders as a function of time and position of the girder in the bridge which is important for the system reliability load model.