U.S.-Japan Cooperative Research Program on precast seismic structural system (PRESSS) has started in 1990 aiming rationalization of construction work. Through this project, the targets from Japan side were to establish “new design guidelines for precast reinforced concrete buildings”, “design manual of precast connections” and “guidelines of precast concrete construction”. This report mainly describes how to consider new design concept for precast connections.

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The present paper reviews researches on constitutive laws (stress-strain relations) for concrete continuum and reinforced concrete, which are necessary in numerical structural analysis, such as finite element method. Among constitutive laws for concrete continuum that are described in a control volume with size of several times of maximum aggregate size, plasticity models, damage models, combined models of the both and micro-structure-based models are summarized. It is explained that constitutive laws for reinforced concrete derived for a control volume of 30-50 cm square concrete element with distributed cracks are independent of crack density and crack number owing to the trade-off mechanisms among those effects. A constitutive model for a reinforced concrete discrete crack, that is derived by combining constitutive models for both reinforcement and crack interface, deals with a single crack crossing reinforcement and predicts path dependency which can not be described by each of the models. Future tasks are to develop well-balanced constitutive laws among theoretical clearness, accuracy and application limit and to verify systematically them and the analytical methods from the level of structural members.

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In recent years, wind-induced cable vibrations of cable-stayed bridge have been observed, and phenomena of these have become a major problem in the wind engineering. This paper outlines wind-induced cable vibrations and the countermeasures against such vibrations, and describes the state of the art by referring to the experiences in Japanese prestressed concrete cable-stayed bridges.

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ELCM, Extended Layer Construction Method, is adopted in Nakasujigawa Dam project. Downstream face of the dam is designed in steps, which takes most advantage of ELCM. Design of landscape is totally performed in addition its structural design. Some of the trials are completed in a manner to accord with its total conception of the design of landscape, including the steps. In this paper the authors mention the conception and the trials with their construction in site.

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RC slabs of steel bridges on Chuo Expressway Fuji-Yoshida route are damaged by chloride corrosion due to highly chloride contents in concrete. The extent of deterioration was assessed on three bridges, and replacement of slab was proposed at Furukawado Bridge. Since the expressway is under operation, considerations were given so as to minimize the work period and to facilitate the implementation. This report presents the slab replacement work as one of countermeasures for chloride corrosion, employing new technology such as precast PC slab, specially designed slab replacement equipment and slip-form method for concrete wall.

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The Higashi-Ohgishima Viaduct (tentative name) is a 9-span continuous prestressed concrete box girder bridge which constitutes a part of the Metropolitan Expressway Bay-shore Route (4th phase) scheduled to open 6th of Heisei. As it was necessary to construct the viaduct which flys over subface type road, City Road of Kawasaki, without hindering the traffic flow bellow, a cantilever method accompanied with auxiliary suspension diagonal cables from pylon situated on the already completed main girder was adopted. Continuous measurements on the stress and strain of suspending cables and concrete, for the purpose of controlling the error, were successfully carried out. This is one of the largest examples in Japan ever constructed with this type of method with respect to the magnitude of width of 14.25 m and length of cantilever section of 40 m.

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