This research is constituted of the reproduction of macro-cell steel corrosion in concrete based on two methods and of the numerical approach to experimental results. The firsrt idea for macro-cell corrosion formation is that the change of resistivity in concrete makes macro-cell generated, and the second one is that the change of connecting divided steels, which has different half-cell potentials, makes macro-cell generated. It is clarified that the multi-circuit model on macro-cell corrosion is applied to experimental results and difference in half-cell potential in the form of micro-cell corrosion promotes macro-cell corrosion circuit. Furthermore, the influenceson crack width to the formation of macro-cell corrosion circuit became clear.

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In order to clarify the lowering effect of immersion liquid on the compressive strength of concrete, nucleation of internal cracks under static compression was investigated on the basis of surface energy. The energy consumed in the nucleation of cracks is calculated from the area of hysteresis loop on stress-strain relation in the compression test. As a result, it is found that the calculated energy is closely related to the surface energy in the nucleation of cracks. It is also found that the energy increases exponentially with the increase of strain, and decreases with the increase of moisture contents or surface tension of immersion liquid under the same strain ratio. Consequently, it can be concluded that the decrease of compressive strength of concrete due to immersion of liquid results from the decrease of surface energy consumed in the nucleation of internal cracks.

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A uniaxial fatigue test was used to investigate whether an endurance limit exists in asphalt mixtures. The level of strain at which no increase in fatigue damage occurs was estimated from changes in phase angle during the fatigue test, and investigation was performed at strain levels above and below this level. The number of load applications to failure was estimated from the rate of stiffness change observed in the present test on the basis of the relationship between the rate and the number obtained from existing studies. The test results indicate that there is no endurance limit in dense-graded asphalt mixtures (13) at 10°C when strain is 20μm/m or greater.

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The objective of this paper is to develop a new dynamic backcalculation method (Wave-BALM) for structural evaluation from FWD time series data. The main feature of the method lies in implementation of the theoretical solution for wave propagation in multilayered viscoelastic media composed of Voigt model due to an action of impulsive force. Viscoelastic layer parameters are estimated by backcalculation. In the backcalculation measured and computed deflections are matched by the Gauss Newton method coupled with truncated singular value decomposition. The results obtained by backcalculating measured FWD data using the method are compared with the results from Dyna-BALM. Both results are found similar but Wave-BALM surpasses Dyna-BALM in terms of variations of backcalculated results.

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First, seismic analysis method for bridge piers with steel corrosion was established, and the maximum amount of reinforcing bar corrosion to maintain the seismic safety of a corrosion-free RC bridge pier was examined based on the reliability analysis. Then, the probability that the corrosion state of reinforcing bar will reach a particular value within the lifetime of RC bridge pier was calculated by corrosion progress model. The calculations for the cover to ensure that the probability is the same as the target value are presented. As a result, when the limit state of durability design of RC bridge piers is set as corrosion crack initiation, the degradation of seismic safety due to reinforcing bar corrosion during its lifetime can be assumed to be negligible and a rational cover can be determined.

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A new adsorption isotherm derived from the energy equilibrium on thermodynamics and characteristic of pore size distribution is proposed. In traditional terms, the equation has the form:

V =	ΩV0	,
	Ω−ln(h)

where V and h are the amount adsorbed per unit mass of the adsorbent and relative humidity, respectively. V₀ is the volume of adsorption under saturated conditions, which corresponds to the total pore volume. Ω is a constant reflecting the characteristics of the pore size distribution, temperature and the type of adsorbate. This equation can be used to express experimental data of the water adsorption isotherm over a wide range of humidity conditions with various cement materials.

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Backcalculation is a method to estimate pavement layer-elastic moduli using FWD data. This method commonly uses the peak (maximum) values of measured load and surface deflection data. When these peak values are utilized along with static analysis, the method is called static backcalculation. Attention has drawn on dynamic backcalculation which utilizes time series FWD data and estimates layer-elastic modulus and damping coefficient of pavement layers. In addition two those parameters, identification of layer densities is the aim of this paper. The method of identification has been developed and verified by using numerical simulation and measured FWD data.

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Few studies have been made on the seismic behavior of columns repaired or re-retrofitted after great seismic damage. Actions need to be taken in the case of a great earthquake.
In this study, a scale model of bridge column of a retrofitted reinforced concrete rigid-framed railway viaduct was subjected to alternate loading and unloading to provide great hysteretic deformation. Then, the damaged column was repaired and retrofitted again and an experimental study was made of the column to identify the deformability after re-retrofit through another round of reversed cyclic loading.

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This paper presents numerical studies on influence of corrosion distribution of steel reinforcing bars on flexural behavior of reinforced concrete beams. Steel corrosion is modeled by reducing cross sectional areas of reinforcement elements and bond strength of linkage elements according to corrosion levels. Corrosion distribution of steel reinforcing bars is assumed as a simple sine curve, and its property is decided by an average corrosion weight loss and a coefficient of variation. The flexural capacity of reinforced concrete beams with steel corrosion depends on the minimum cross sectional area of steel bars, and the ductility of beams is influenced by the condition of bond deterioration.

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In this study, numerical analyses of concrete specimens under uniaxil compression and triaxial compression using three dimensional Rigid-Body-Spring Model was conducted for quantitative evaluation of concrete fracture in compression. Constitutive models are developed and the material parameters are calibrated by fitting the response of concrete in uniaxial tension, uniaxil compression hydrostatic compression and laterally confined compression, which were reported in the literatures. It was confirmed that the model can reasonably evaluate the macroscopic strain-softening and localization behavior in uniaxial compression and the increase of strength and negative slope of the strain softening region with increasing of lateral pressure.

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In this study, the experimental estimation for influence of the shear and anchor reinforcement on the characteristics of residual strength of RC beams, of which failure mode is flexural under the non-corrosion, with corrosion was carried out. It is noted that the residual flexural behavior is different due to the occurrence of non-uniformity of main reinforcement corrosion. In case of uniform corrosion, the flexural failure of RC beams, of which the residual shear reinforcement is sufficient, occurs, on the other hand, the brittle failure occurs by the stress transfer to the shear and anchorage region of main reinforcement. In case of non-uniform corrosion, the flexural failure occurs due to the localized deformation on the region of remarkable corrosion.

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For effective use of coal ashes generated from coal-fired power plants, the research which aims at improvement of environment in spray work by decreasing dust has been done by using type-1 fly ash as admixture of sprayed concrete. As a result, the use of type-1 fly ash in place of fine aggregate confirmed that the water content of base concrete is decreased, and that the resistance against material segregation of base concrete is improved. From the result of the spray tests executed at the model tunnel and the actual road tunnel, the use of standard 100kg/m³ type-1 fly ash in place of fine aggregate confirmed that the excellent work is made by decreasing the amount of dust and rebound during spraying, and that the strength development of sprayed concrete improves excellently from the initial ages over the long ages.

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Airport asphalt pavement was preliminary constructed on concrete slabs in a test site. After construction, optical fiber sensor monitoring and electromagnetic wave radar detection were conducted to find whether they could recognize the residual water inside the pavement. The results showed that the optical fiber sensor buried in the pavement responded quite well with the appearance or disappearance of the residual water. It was also found that the reflection period of the electromagnetic wave was increased about 10 % on average by the existence of the residual water. The fact suggests that the electromagnetic wave radar detection is promising to find the residual water inside the airport asphalt pavement overlying slabs.

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Size effect of deep beams with small shear span to depth ratio (a/d) can be increased by anchorage failure or bearing failure. On the other hand, there are past researches which present that the size effect of deep beams is small in the condition that anchorage failure or bearing failure does not occur. In this study, deep beams whose a/d is 1.0 or 1.5 are loaded considering the influence of effective depth and the bearing area on the size effect and the bearing failure. As a result of the investigation, the estimation method of shear capacity which refers to the past estimation equation is proposed in this study. Consequently, applicability of proposed method is verified with the past experiment data.

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One-pack hybrid high-range water-reducing admixture (HSP1 and HSP2) combining high fluidity and shrinkage-reducing capability for the durability improved concrete with a wide range of target strength was developed and examined. HSP1 for normal concrete showed excellent drying shrinkage-reducing performance to achieve a reduction in the drying shrinkage of 15% with respect to that of concrete containing a conventional high-range water-reducing admixture (SP1). On the other hand, HSP2 for high strength concrete showed excellent autogeneous shrinkage-reducing performance to achieve a reduction in the autogeneous shrinkage of 20 to 35% with respect to that of concrete containing a conventional admixture (SP2).

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A high bearing capacity is essential for subgrade to avoid excessive settlement upon constructing slab tracks on earth structures. However, soft diluvial clay layer was visible on a route under planning of a Tohoku-Shinkansen line adjacent to a local town named Shichinohe, and a double-line-integrated reinforced concrete roadbed was developed. We carried out detailed ground investigations to construct slab track on the soft diluvial clay to evaluate the performance of the concrete roadbed. We further carried out on-site cyclic loading tests with application of vibration exciting machinery. Based on the foregoing results, the authors carried out FEM analysis to evaluate deformation characteristics of the concrete roadbed. It was clear that the double-line-integrated reinforced concrete roadbed was able to support properly slab track on the soft diluvial clay subgrade.

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With the current trend toward using Superpave for asphalt mixture design, a study was carried out to assess the possibility of implementing the Superpave mix design procedure for use in airfield. The results were reported in this paper, which begins with a review on the primary differences in the Superpave and Marshall methods. Following this, four asphalt mixtures corresponding to different maximum aggregate particle size (MAPS) are designed by the Superpave mix design procedure, and the normally used medium gradation mixture for each MAPS is designed by the Marshall method. Then, the Superpave mixtures are quantitatively assessed in rutting resistance by wheel tracking tests compared with the Marshall-designed medium gradation mixtures. Results indicate that the Superpave mixtures give superior rutting resistance to Marshall mixtures. So it is preliminarily concluded that the Superpave mix design method offers a promise for use in heavy-duty pavements in airfield instead of Marshall method.

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