The project developed a proposed guideline for the evaluation of existing bridges, and is intended to replace the present aashto manual for maintenance inspection of bridges. The proposed procedure for steel and prestressed concrete spans eliminates the existing inventory and operating stress levels for posting and provides rating levels which depend on the available information. The report reviews the load information available from bridge tests and weigh-in-motion (wim) studies. Statistical data are provided on overweight trucks, vehicle configuration, multiple presence, load distribution, and dynamic impact, and are used in a prediction model to indicate extreme load effect. Similarly, data were gathered on component strength for steel and prestressed concrete members, and also on corrosion strength. Statistical descriptions of load and strength are presented in a reliability formulation to assess the safety index corresponding to the safety margins. To simplify calculations the existing aashto rating method for vehicles are used to determine nominal member load effects.
Abstract