Diagnostic Load Test of Continuous Prestressed Box Girder Bridge

A main objective of the present investigation is to obtain structural responses of a continuous box girder bridge employing a diagnostic load test. The bridge under consideration is a 7-span, prestressed concrete structure with the total length of 665 meters. Four 3-axle trucks are employed in the diagnostic load test. Strains and vibratory motions of the girder are measured and reported. Varying speeds of test trucks are considered during the dynamic test. Natural frequencies and mode shapes of the box girder are determined based on modal analysis. Correlation between natural frequencies of the box girder obtained from field measurement and a finite element model is also illustrated. Wavelet analysis is employed to decompose girder strains into static and dynamic components, and dynamic amplification factors are determined and reported. In addition, the results of long-term measurement of pot bearing movements subjected to variations of surrounding temperature are also presented.