Development of new cable-stayd systems with economy and high durability

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The main aim of this research project is to develop new cable-stayd bridge systems with lower construction cost and higher durability.In foreign countries, cable-stayd 2-I composite girder bridges are used becase of their lower construction cost. However, their durability has not been examined. This is the main reason why this economical system has not been used in Japan so far.In this study, first, utilizing the simplified method for obtaining the stress resultants of main members in cable-stayd bridges, the possibility of such system with a span up to 500 meteres is investigated from statical viewpoints, then the possibilities of them are presented. To examine the durability of the system, a 3D dynamic FEM analysisis developed which includes cable local vibration. Under vehicle loading, it is known that this system does not show peculiar behavior compared with dynamic behavior seen inconventional systems. Further, to cope with unexpected cable vibration, the effectivenessof the installation of viscous damping device and its design methos are presented.Secondly, the structural behavior of a 2-I composite girder is studied. A FEM analysis is developed to obtain the stress in the composite girder in cable-stayd bridge, then the method to obtain the shear-lag in concrete slab is proposed. Creep and shrinkage analysis is also carried out and the impotrance of their phenomena is suggested. From FEM analysis, the effect of transvese-stiffening system on the 3-D structural characteris-tics of the 2-I girder bridge is investigated. From the calculation, the possibility of the simple transverse-stiffening system is obtained.