A study is performed to develope the new-type steel box girder bridge with open top and inclined web and to utilize it in practice. This study consists of 1) a study on the design and construction of steel box with open top and inclined web, 2) a stud...
A study is performed to develope the new-type steel box girder bridge with open top and inclined web and to utilize it in practice. This study consists of 1) a study on the design and construction of steel box with open top and inclined web, 2) a study on the development of deck which is suited to the new-type steel box girder, 3)a study on the tests for the durability and the ultimate strength of steel box girder and composite bridge system, etc. Based on these studies, the design and construction methods are developed and the guidelines are presented for the steel box girder bridges of open top and inclined web. This study was performed in 3 parts of "the steel box girder", "the precast concrete deck" and "the composite system". On "the steel box girder" part, the methods are developed to prevent the distortions of steel box girder and to maintain the desired geometries before the concrete deck are completely cured to contribute to the total stiffness, during the manufacturing and the erection stages. In this part, the design guidelines for the upper lateral braces and the internal diaphragms are specified, which is verified by several experiments. Besides, the ultimate strengths of flanges and inclined webs are testified by large scale experiments. On "the precast concrete deck" the influences of the longitudinal prestresses on the prevention of the cracks in precast deck joints, and the influences of the thickness of bedding layer on the fatigue, strengths are testified. To reduce the negative moments in the supports, the hybrid system of internal prestress with partial external prestress or that of internal prestress with jacking up-down method are developed and testified. In case of using partial external prestress the enhancement of crack resistance by using the method, is throughly studied by using the experiments. The precast deck system and open-top steel box girder bridge. with the precast deck system are developed to be used in practice. On "the composite system", the crack-resistant strength and structural safety in ultimate load states are tested for the proposed bridge system. In the experiments, large scale bridge test models of two 20m long model and one 40m long model are used to reduce the scale effects and to make the tests close to the real problems.