Bridge evaluation based on field measurements

The objective of this study is (1) to develop site-specific and component-specific live load models, (2) to identify efficient live load data collection methods which do not require traffic control, and (3) to develop an effective bridge evaluation procedure to accommodate the site-specific live load.;Weights of trucks were measured using bridge weigh-in-motion system for the development of site-specific live load model and an efficient live load data collection method. The measurements indicate that a significant variation in live load occurs even within a given geographic area. The cumulative distribution functions of lane moment, lane shear, and GVW were developed from the analysis of bridge weigh-in-motion test data. The statistical models for girder distribution and impact factors were developed from the measured strain under normal truck traffic.;The major contribution of the study is the establishment of the relationship among statistical distributions of gross vehicle weight (GVW), lane moment, and lane shear. The relationships were developed by an extensive statistical analysis of field measurements. The relationship between GVW and moment provides a basis for efficient live load data collection method because GVW distribution can be derived from moment distributions which, in turn, can be obtained from strain measurements. This is very important because strains can be measured without any traffic control, which is the most expensive part of the field work. The method maintains most advantages of the bridge weigh-in-motion system and yet does not require roadway sensors on the bridge. In addition, the measured strains can be used to derive statistics of girder distribution and impact factors under normal truck traffic.;The relationship between moment and shear greatly simplifies the incorporation of the site-specific live load into the bridge evaluation procedure. It has been found that moment and shear distributions are practically identical. Therefore, the same live load factor can be used for both moment and shear.;The site-specific live load factors were developed to reflect the actual load conditions. In addition, the relationship between the site-specific live load factors and the measured maximum gross vehicle weights was established. It can be used to determine the site-specific live load factors from the measured maximum gross vehicle weights without a complete reliability analysis.