Objective Load Rating of a Steel-Girder Bridge Using Structural Modeling and Health Monitoring

Abstract

The future of highway infrastructure in the United States is at a critical junction. Nearly one-third of U.S. bridges are nearing the end of their design life, and one in ten bridges is categorized as structurally deficient. While the design and construction of the next generation of U.S. highway bridges is underway, existing bridges must be maintained through proper inspection and load rating. This paper proposes an objective load rating protocol that takes advantage of a shift in the bridge design, construction, and management paradigm to include structural modeling, instrumentation, and nondestructive testing. A baseline structural model is created and verified using structural health monitoring (SHM) data collected during a controlled static load test. The structural model is then used to calculate load rating factors of the bridge at both current and simulated damaged conditions. The resulting load rating factors are compared with the AASHTO load resistance factor rating method.