Field Measurement and Load Testing of the Rama IX Cable-Stayed Bridge

In this paper, field measurement and diagnostic load test carried out for the Rama IX Bridge, as part of bridge in-depth inspection and evaluation is presented. One of the main objectives of the investigation is to better understand the physical behaviors of the aging bridge employing field measurements and to reduce uncertainties, related to material properties, boundary conditions and stiffness contribution as well as any influence of damage and deterioration, in structural evaluation of the bridge structure. A modal analysis is adopted to determine modal properties of the cables, steel box girder, and pylons. A number of three-axle test trucks with predetermined loads are employed in the diagnostic load test. Cable frequencies and strains obtained under the applications of test trucks are presented. A wavelet analysis is adopted for decomposition of strains into static and dynamic components in determination of dynamic effects on structural responses.