A STUDY ON LOAD-CARRYING CAPACITY EVALUATION OF EXISTING BRIDGES USING LOAD RATING

Abstract

 There are no official standard specifications and manuals for load-carrying capacity evaluation of existing bridges in Japan, and accordingly, most existing bridges are evaluated with design specifications for new bridges. In this study, a case study of load rating for five existing Japanese bridges with different structural types is carried out using the grillage analysis and 3D FEM analysis. Furthermore, the case study employs both current and previous versions of specifications and live loads for highway bridges to discuss rating results changes. The results show that rating factors depend on bridge types and increased dead loads due to retrofitting after completion. The rating factors based on the current design codes show larger values than those based on the previous ones, since the overall safety factor is decreased in the current codes. FEM analysis proffers the larger rating factors than the frame analysis used in design practices. The present case studies show that the rating factor is inversely proportional to the girder depth.