Cost of concrete structures has to include maintenance cost in addition to initial construction cost from the standpoint of economical usage. The paper deals with life cycle cost of RC piers constructed under sea environments and tries to evaluate life cycle cost (CLI). The functionality of structures decreases according as time elapses because of salt attack. It is, therefore, necessary to estimate deterioration of structures, to which the paper applies the probability approach and constructs the program in consideration of uncertainty. Law of expected minimum cost is applied to calculate life cycle cost and the calculation flow of CLI is proposed. The calculation technique is, then, shown to the existing pier according as the calculation flow. Finally, the adequate interval of maintenance is indicated.

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Concrete cooled to very low temperature cyclically is deteriorated by ice formation in mien-pores. Although the factors to the deterioration are various, storage at very low temperature is mentioned as one of the factors. In practice, storage of cryogenic structure is kept at very low temperatures, and as such, it is important to take into consideration the influence of storage at such low temperature on the deterioration of concrete. It is expected that the cooling rate and minimum temperature have a close relationship to each other in the concrete deterioration process. Thus, in this study, the influence of storage on the deterioration of concrete at various minimum temperatures and cooling rates was researched on, taking into consideration the different W/C and air content.

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The technology of guss asphalt has been introduced from Germany since 1948 and has been used widely as a paving material in steel deck of bridges. Problems due to the heavy duty traffic are occurred such as rutting, cracking, and construction technology in steep slope of the bridge as well. In the study, the guss asphalt is added with steel fiber aiming at improving the structural viscosity, and thus the resistance ability of the mixtures to rutting and cracking. In the paper, the basic physical properties and construction characteristics of the guss asphalt added with steel fiber are reported, compared with those of Trinidad Lake Asphalt.

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To assess the application of steel fiber reinforced high-strength concrete with compressive strength of over 100 (N/mm²) in RC structures subjected to impact/impulsive loads, the dynamic mechanical properties of steel fiber reinforced high-strength concrete under high strain-rates and triaxial stress states are essential. Thus, this study is to investigate the behavior of steel fiber reinforced high-strength mortar subjected to high strain-rates and triaxial stresses. The volume fraction of steel fibers, the confining pressure and the loading rate are chosen as test parameters. From test results, the effects of these parameters on the mechanical properties of steel fiber reinforced high-strength mortar are examined. Furthermore, based on the concept of the equivalent uniaxial strain, the orthotropic constitutive model with the strain-rate effects is proposed.

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Damage of marine structures due to salt attack is well known as one of major deterioration processes of reinforced concrete (RC) structures. In order to investigate diffusion characteristics of chloride ions in concrete piers of Sin-Kitakyusyu Airport Bridge, exposure tests of RC beams were carried out for six years. Results on chloride diffusion were studied in comparison with the continuous diffusion tests in a laboratory. Based on these results, a performance-based analysis on the salt attack of the piers is conducted to confirm the durability of the concrete piers.

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This paper deals with Impact Acoustics methods to identify the sizes and vertical locations of defects in concrete. In this study, the maximum amplitude and frequency distribution, those were obtained from received elastic waveforms when concrete surface was impacted, were defined as ‘Impact Acoustics indices’ for defects evaluation. Quantitative relations between the Impact Acoustics indices and defects indices were both experimentally and analytically investigated. Influences of impact locations and concrete properties on the Impact Acoustics indices were also examined. As the results, it was revealed that the Impact Acoustics parameters used were very effective for quantitative evaluation of defects with taking consideration of impact locations on a concrete surface.

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The hydration reaction in concrete has to be modeled for estimation of concrete performance in the mixture proportion design as optional materials or environmental conditions. This paper is to propose the multi-component model for hydration reaction based on cellular automata algorithm that applicable to wide variety of Portland cement types. Cement paste miniature for cement and water reaction medium is developed by 100×100×100 pixels which 1 pixel is 1μm cubic. Hydration reaction rate is assumed identical with penetration rate. Each penetration rate of cement mineral is expressed with basic penetration rate and 4 reduction parameters. The hydration products are calculated with proposed chemical hydration reaction equation. The proposed model was verified with experimental results of hydration degree, temperature rise, Ca (OH)₂ hydration product and pore volume.

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In order to clarify the feature of seismic design codes, nonlinear dynamic analysis of RC piers that have been designed by the seismic design codes of Japan, United States, Europe, and New Zealand, is carried out. In this study, Lattice Equivalent Continuum Model (LECM) is used as an analytical method. As a result of comparing the analytical results, the feature of the seismic design codes of each country is clarified. And LECM is possible to apply for solving the dynamic problem.

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In this study, the permanent deformation at base course surface was examined using the Westergaard's model based on the results of the static and the cyclic loading tests with a concrete pavement at the Public Works Research Institute in August 1997. The analytical results of the static loading test showed that, for presice calculation of the deflection or pressure, the base course reaction modulus should be modified based on the Boussinesq's model as Vesic had suggested. And in the cyclic loading test, the development of a permanent deformation of base course surface with cyclic loads was observed, and the decreasing of reaction modulus due to the permanent deformation was confirmed.

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The influence of ASR damage on structural performance was investigated through reversed cyclic loading tests on five RC column specimens by situating under influence of ASR for 3.5 years. It was found that load carrying capacity and ductility of ASR damaged columns were almost the same as those of sound ones. However, there were some differences in the mechanical properties between damaged and sound RC columns, such as the process and state of failure, absorption capacity of seismic energy, etc. Moreover, the PC confinement method was confirmed to be effective to strengthen ASR damaged columns from the viewpoints of load carrying capacity and ductility.

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The surface void of self-compacting concrete has a tendency to be generated easily by its high viscosity and non-compaction. In this research, the relation between the generation factor of the surface void and the mechanism of the generations was considered experimentally. The examined items are shown below. (1) Form release agent's types were changed, and the ratio of depth and diameter of surface void (h/d) was measured. As a result, when hid was large, the surface void was generated internally concrete. (2) The contact angle was measured from the maximum height of drop of liquid on horizontal form. And, the degree of wettability of form was shown numerically. And, the relation between wettability and surface void was made clear. (3) The void was artificially generated on the surface of form. And, the relation between the maximum volume of void which adhered to form and the angle of the form was measured.

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In order to clarify the seismic performance of reinforced concrete (RC) bridge piers under seismic loading, the computing program using the lattice model, which is an analytical model for determining the change in the shear resisting mechanism, has been developed. By the comparison between the experimental and analytical results, it has been confirmed that the static lattice model analysis can predict the load-carrying capacity and the ductility of RC bridge piers subjected to cyclic loadings. In addition, by the comparison between the results obtained by the shaking table tests and the dynamic lattice model analysis, it is found that the dynamic behavior of RC bridge piers subjected to ground motion can be appropriately evaluated. Finally, it has been proved that the influence of the transverse reinforcement on the seismic performance can be properly estimated in terms of the energy absorption of RC bridge piers.

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Cement manufactured from municipal solid wastes has been developed. About 50% of raw materials for this cement are wastes. This cement contains a larger amount of C₃A and chlorine than normal portland cement. Therefore steel corrosion is worried about when this cement is used for reinforced concrete. In this study, the possibility of steel corrosion for this cement is investigated in terms of pore solution composition and its changes. As a result, although the chloride ion concentration of pore solution for this cement is higher than for normal portland cement, the ratio of the chloride ion concentration relative to the hydroxide ion concentration is law. In addition, the amount of chloride accommodated by cement hydrates is high because of high C₃A content. It is concluded that the possibility of steel corrosion for this cement is as well as for normal portland cement.

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Fluorescence microscopic examinations were conducted to identify damages induced by restraining autogenous shrinkage. Characteristics of fluorescent areas and their correspondence to autogenous shrinkage behavior of high strength concretes were discussed. Silica fume concrete exhibited a greater creep potential when loaded at very early ages. The microstructure in sealed concretes was porous, especially in the interfacial regions around aggregate particles. In addition, sealed silica fume concretes contained many Hadley grains. These features of microstructure were not observed in water ponded concretes. The detected fluorescent areas may be defects caused by self-desiccation and autogenous shrinkage. The flaws had little effects on the development of strength. However, the presence of thin gaps around remnant cement particles may increase creep deformation to relieve internal stresses.

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Freeze-thaw resistance of concrete with sufficient entrained air was tested at the ages of about 12hrs to 14 days by a conventional rapid freezing and thawing test. The effect of continued cement hydration during the test was eliminated from the test results by applying a data-analyzing technique which had been proposed by the authors.
It was shown that the freeze-thaw durability of early-age concrete was dependent on its strength and degree of saturation, and that a minimum compressive strength of 24N/mm² was required for a water-saturated concrete to possess a sufficient freeze-thaw durability. Also shown was that a curing method similar to sealed curing was preferable in cold weather concreting rather than a moist curing as recommended in Japanese specifications.

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This paper presents structural characteristics of a prestressed concrete deck bridge supported from below.
The prestressed concrete deck bridge supported from below consist of roadway deck, struts which support the deck, and subtending cables. The subtending forces balance the permanent loads as perfectly as possible.
A series of tests under static and dynamic loading are carried out on the Ayumi Bridge in Numazu City. The analytical model of the structure is confirmed by comparing the analytical results with the experimental results.
The dynamic responses of the bridge under the passage of moving vehicle are analysed for a parametric study. The non-linear analysis for ultimate loading was carried out using the fiber model program taking the material and geometrical nonlinearity into account.

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This paper presents numerical analyses of reinforced concrete (RC) panels subjected to pure shear forces using rigid-body-spring models. RC members under certain conditions exhibit brittle failure with strain localization relative to ordinary shear failure. This failure mode is called a sliding shear failure whose mechanisms of failure are not well clarified. The rigid-body-spring model is one of the discrete type models that are suited towards problems where material discontinuities are dominant. Numerical predictions obtained by the model are therefore useful to comprehensively understand the mechanisms of the failure. The parametric analyses with regard to compressive strength of concrete, yield strength of reinforcement, and reinforcing ratio are also carried out to investigate the conditions when the sliding shear failure occurs.

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In our country where the plain part is already occupied, in the near future, the highway construction in mountains zone will become main and then it is expected that a culvert in high embankment will increase in number. On the other hand, if it is taken into consideration that the financial situation of our country in the 21st century becomes still severer, it is necessary to promote cost reduction of public-works further. This paper presents the contents of study on the design and utilization of a new type culvert method, namely RCC culvert that had been developed for the purpose of time-necessary-for-completion shortening, cost-of-construction reduction, and improvement in durability.

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In this paper, our purpose is to make it clear as follows the characteristics of RCD concrete in the case of varying the mixing ratio of each kind of three coal powders; the characteristics of Slump Dam Concrete in the case of the mixing ratio of each kind of three coal powders and filler.
We found some interesting results as follows: in RCD concrete, the VC value became lower, the compressive strength became higher at the most efficient mixing ratios in the case of any three coal powders; in Slump Dam Concrete, the compressive strength became higher, whereas slump decreases in the case of increasing the mixing ratio of each kind of three coal powders and filler.

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Debonding along FRP-concrete interface is regarded as one of the most significant fracturing behaviors in FRP-strengthened concrete structures. To model FRP-concrete interfacial bond behavior in experiment, several kinds of local shear stress-relative displacement (τ-δ_t) relationships are proposed. The results of finite element simulation and theoretical derivation are compared. The linear ascending and descending τ-δ_t, relationship is regarded as an applicable and accurate model, and is used in this paper. The observed experimental failure modes and cracking behaviors are simulated through a parametric study of bond interface properties and concrete fracture energy, whose effects on load-carrying capacity and concrete crack distribution are studied.

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Due to expansion of corrosive products, cracks are nucleated around reinforcement in concrete. Initiation and propagation of these cracks are studied by experimentally and then analytically by the Boundary Element Method (BEM). The maximum circumferential stress criterion is applied to trace the crack extension of mixed-mode cracking. By employing the two-domain BEM, crack orientations are evaluated from the stress intensity factors of mode I and mode II. In BEM analysis, the ratios of stress intensity factors of mode I to mode II (K_I/K_II) are studied for the different types of crack patterns, which are observed as corrosion cracking.

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