This study proposes that a box girder bridge using butterfly panels fabricated from ultra high strength fiber reinforced concrete, or UFC, to its web section, with the aim of decreasing self weight and streamlining the construction process. Initially, shear tests were conducted with 1/2 size UFC butterfly panels in order to evaluate the shear behavior of this structure. In addition, non-linear FEM analysis was conducted for a virtual model of an entire bridge having this web in order to evaluate the behavior of the entire bridge system. Based on these results, in this paper the authors propose the design method for this structure.

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  A method for structural reliability analysis of concrete beams under marine environment over lifetime was proposed. In the proposed method, uncertainties in evaluating actions and environmental influences are considered based on live load hazard and chloride attack hazard, and uncertainties in evaluating steel corrosion process, structural performance were also explicitly considered. Importance of considering the properties of live load and the hazard of chloride attack in the design process was clarified.

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  The design fatigue strength formula specified in the JSCE standard specifications for concrete structures reflects the effect of moisture condition of concrete; however, the effects of liquids other than water are not considered. Therefore, safety against fatigue failure of concrete structures in a marine environment or of slab concrete through which anti-freezing agents permeate requires more consideration. To ensure safety against fatigue failure, a mechanism for lowering the fatigue strength of concrete immersed in liquids has to be clarified. In this study, the fatigue strength of concrete under compression was investigated from the viewpoints of deformation and energy absorption properties of the concrete specimen. It was observed that the increment of strain per cycle becomes greater with an increase in the surface tension of the liquid, due to the decrease in the interfacial energy between solid and liquid. This strain increment led to the shortening of the fatigue life of concrete. Herein, a modified Goodman diagram in which the static strength of concrete in the wet condition is set as a standard value of stress ratio is proposed.

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  When an anchorage zone of RC member is damaged, the remaining loading performance drops significantly with a few typical diagonal cracks. The loading performance recovery by strengthening the damaged part directly sometimes becomes absolutely difficult because the diagonal cracks develop from the tips of the existing crack at the anchorage zones. One practicable effort is strengthening the expected zones where the diagonal cracks will develop. There is no effect is observed in the experiment result when steel bars are adopted as the strengthening material due to the stiffness increases abruptly and the cracks avoid to across these bars. A numerical analysis which could simulate the experimental work was used also to perform a sensitivity analysis. By using this verification, the requirements to recover the loading performance by strengthening the expected zones became clear. The effect by this strengthening method is verified by the experiment.

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  This paper presents the results of fracture analysis by means of three-dimensional meso-scale analysis concerning discretized short fibers. This technique can consider the mechanical properties of matrix, fiber and their interface. The tensile fracture analyses were conducted for two kind of Strain Hardening Cementitious Composites (SHCC). (i.e. Engineered Cementitous Composites, ECC and Ultra High Performance Strain Hardening Cementitous Composites, UHP-SHCC). Fracture behaviors including strain hardening behavior and multiple fine cracking were roughly simulated through the developed technique. Parametric studies concerning fiber distribution, variation of matrix strength and fracture energy were also carried out to interpret the fracture mechanism of strain hardeing materials. It was clarified that homogeneity of fiber distribution and heterogeneity of matrix were important parameters to obtain higher strength and strain capacity of the composites.

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  For the durability enhancement of port RC structures, corrosion resistant property of three types of stainless steel bars (SUS430, SUS304 and SUS316) in concrete was studied by the exposure tests under marine environment. Results obtained are as follows. i) Each chloride threshold level for corrosion of these stainless steels was estimated higher than 12 kg/m³ at least. ii) The upper limit of crack width for corrosion in case of these stainless steel bars can be increased than that in case of carbon steel bar. iii) In case that stainless steel bar is applied to port RC structures, the life cycle cost can be lower than the case of carbon steel bar.

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