The objects of the study were columns of reinforced concrete viaducts used in large numbers for railway and urban transportation structures. The influences of variable factors such as longitudinal reinforcement ratio, hoop ratio, and axial load on behaviors of members such as limit states of crack occurrence, yielding and ultimate state of member, ductility, and load-deflection characteristics under static alternating cyclic loads were experimentally investigated.
As a result, it was concluded that the load-deflection loop can be modelled as a maximum-point-directed type without slipping, that among various variable factors the influence of longitudinal reinforcement ratio is extremely great, and that plastic hinge length and longitudinal crack formation are determined by the combination of the quantities of longitudinal reinforcement and hoop reinforcement.

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This paper deals with the analysis of reinforced concrete beam members in flexure on the assumption that after deformed they retain the original planarity of their concrete section while the bond-slip of the steel is allowed for. In an initial effort differential equations governing their bending in the statically linear region are derived based on the potential energy principles; then the finite element formulation of the problem is implemented by use of both high- and low-degree types of shape function elements; and associated numerical examples are subsequently solved whereby to examine the effects of the bond-slip on the bending of r. c. beams in the considered region.
The foregoing is followed by the nonlinear development of a finite element procedure which in a more analogous form to reality is intented as a means of pursuing with a low-degree function element in use deformational behaviors of the structure attended by its cracking in the material-nonlinear region.
As a worked example in point some current analytical result on a cantilever beam is shown in comparison with its experimental correspondent in the literature by way of serving thus to substantiate the use of the presented procedure.

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The objective of this paper is to reveal the characteristics of reactions and hardening process of the compacted coal ashes for effectively utilizing the coal ashes as a subbase and an embankment material. The effects of chemical compositions of coal ashes used, curing temperature, curing period and the addition of some stabilizers on the mechanical properties of the compacted coal ashes were investigated. Furthermore, the reaction processes and microstructure in the compacted coal ashes were elucidated by SEM observation, X-ray diffraction analysis, differential thermal analysis and measurement of pore size distribution. From the experimental results, the relations between seveval engineering properties of the compacted coal ashes and the reaction processes in them were discussed.

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The project has two main objectives: (1) to clarify the vibrating properties of the damaged specimens and (2) to correlate the frequency with the degree of the damage in reinforced concrete tall pier models. The vibrating tests of sixteen models are carried out. The variables are the cycle of the repeated loading and the materials of the specimen, that is, normal strength concrete, high strength concrete, and steel fibered concrete. From the test results, it is obtained that the relationship between the frequency and the degree of the damage is exhibited by an exponential function and that the measured values of the damping factor range from 0.02 to 0.06 as described by other investigators. Based on the test results and the analyses, a damage function and some damage factors are found and defined. Finally, a method for the prediction of the degree of the damage is proposed.

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In massive concrete structures thermal cracks are caused by external restraints in the vicinity of construction joints between old concrete and new one. This paper discusses the results of investigation performed to reduce such a thermal stress, by placing a layer of extraordinarily set-retarded concrete between them. Experimental study was carried out by changing the dosage of setting retarder for four long specimens. It is indicated from the study how to prevent such thermal cracks with the proposed construction method.

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The temperature and strain distributions are observed in a circular prestressed concrete water tank of 10000t capacity. The observed strains are compared with calculated strains obtained from finite element models. Close agreement was obtained for the both strains not only in elastic component but also in creep component. It confirm the propriety of used model and assumption.
25°C difference in the temperature of each wall face is proposed for design from the observed data for 3 years and the meterological data for 15 years. It induced the tensile stress of 5.2MPa at the inside surface of the wall concrete. It is also shown that the reduction of thermal stress by creep effect can not be expected.

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It has been recognized that cracks in concrete have a major effect on the mechanical response of reinforced concrete. This requires the construction of an analytical model representing a single crack in concrete for the nonlinear analysis of reinforced concrete members.
The authors develop a constitutive equation that relates relative displacements and applied stresses on cracked surfaces of concrete in the plane stress state.
In the paper, formulation of the constitutive equation and the characteristics of four basic coefficients contained in the constitutive matrix are described. The proposed model can reflect such typical properties of cracked concrete as aggregate interlocking, crack dilatancy and frictional contact in analyses.

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The pipe cooling method has been used to control temperature rise and thermal stress in mass concrete. However, a practical method to analyze the corelative heat exchange between cooling pipes and mass concrete has not been established. Therefore, an experimental study on the effect of pipe cooling was conducted on actual structures and a analysis using the finite element method was applied to analyze the heat exchange on the field of three dimensional thermal conduction. The method of this analysis and the results of experiment are described in this paper. Results of the analysis well agreed with the experimentally measured data, and it is considerd that the method of this analysis is widely acceptable for practical use. The effect of pipe cooling concrete is also discussed in this paper.

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The objective of this study is to experimentally investigate the effectiveness of repairs by injecting epoxy resin in reinforced concrete (RC) members which have failed due to loss of bond between reinforcement and concrete.
For this purpose, loads are first applied to RC beams having lap splices and RC beams with cutoff of one-half of main tension reinforcing bars, and bond failures are made to occur. Subsequently, epoxy resin is injected in the cracks formed using low pressure and as much time as practicable for injection.
As a result, although the behavior modes of members after repairs may be altered, it is ascertained that capacities, deformabilities, and energy absorptions are not less than those with the beams in their original conditions. Accordingly, it may be said that epoxy resin injection is extremely effective as a method of repairing RC members in which bond failure has occurred.

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The flexural fatigue strength of concrete is a basic character of pavement design. Accordingly, this research is aimed at clarifying the effects of stress ratio (σ_min/σ_max) and maximum size of coarse aggregate to the flexural fatigue strength of concrete by conducting various tests. As results, it was found that the effects of the both factors are minimal and that they need not be considered at actual designing. Due to the fact that fatigue phenomena reveals scatter in general, flexural fatigue equations were obtained with the consideration of probability of failure. In comparing the life of concrete pavements calculated from test results and the results of condition survey of concrete pavements in Tohoku Region, the validity of flexural fatigue equations were verified.

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In airport pavement, the design load is extraordinarily large and the variety of running speed is very wide. Further more, the loading condition of each pavement differs greatly depending on its location and object.
From these characteristics, there are still many unknown structural factors in designing airport pavement.
The main parts of the pavements such as runway and apron, of New Tokyo International Airport, were constructed from 1971 to 1973. To collect the response data of the pavements by aircraft loads, pressure gauges, deflection meters and strain gauges were set at two points of the runway and one point of apron during the construction period.
Just after the completion of pavements in 1972 and 1973, the tests were conducted using the testing vehicle with large type aircraft gear wheels, and the response data by static and dynamic loads were obtained by the above instruments.
After opening of the airport in May 1978, the dynamic response data of vertical stress in the subbases and subgrades of the runway and apron pavements were collected using the actual aircraft.
This thesis clarifies the characteristics of different usage conditions of runway and apron facilities by comparing the static and dynamic response of the testing vehicle with the dynamic response of aircrafts, and also deals with structural evaluation of both runway and apron pavements.

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This paper presents the experimental results regarding compressive strength, flexural strength, Young's modulus and Poisson's ratio of expansive concrete subjected to uniaxial restraint. The uniaxial restraint with which a compressive strength test is carried out, does hardly affect the compressive strength and Young's modulus of expansive concrete, but the Poisson's ratio with the restraint is larger than that without one.
Young's moduli obtained by releasing the uniaxial restraint are almost the same as ones obtained by loading. The expansive concrete shows reduction in Young's modulus due to expansion even though the compressive strength is the same as one of ordinary concrete. When the restraining steel ratio is high, reduction of both strength and Young's modulus is alleviated. However, there is a limit of the restraining steel ratio in case of restrained only in a uniaxial direction. The change with increased age in mechanical behavior of expansive concrete is larger than that of ordinary concrete not containing expansive admixture.

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The purpose of this paper is to clarify the torsional properties of reinforced concrete members subjected to bending, shear and torsion. Firstly, theoretical expressions based on a space truss model are described.
This theory can predict not only the strength but also the angle of twist, the steel strains and the concrete strains throughout the loading history. Second, rectangular solid and hollow sectional reinforced concrete beams were tested in order to grasp the mechanical behaviours, that is, strengths, cracking patterns and deformations of such members. The presented analysis can predict very well the tested torsional behaviours.

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In the past, the equation for the shear strength of reinforced concrete beams without web reinforcement had been proposed, whereas the result of large-size beam tests carried out recently revealed that the nominal shear strength was inversely proportional to the fourth root of the effective depth. Taking this fact into account, the proposed equation is revaluated and a new equation is derived. The validity of the new equation is verified by the authors using tests of large-size beams subjected to a concentrated load. Finally, suggestions concerning application of the new equation for design are mentioned.

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Bond behavior in the neighborhood of a primary transverse crack was investigated using deformed bars with only a single transverse rib, Test results showed that the deterioration of bond strength in this region was remarkable, and that it was necessary to take account of the bond strength and slip stiffness defined by the function of the distance from crack in the numerical analysis of RC members.
Furthermore, the nonlinear analyses of shear spring systems modeling the past authors' pull-out tests were carried out, in which the above mentioned test results were used to estimate the strength and stiffness of the shear springs. The comparison of the bond behavior between in analyses and in tests exhibited good agreement, provided that the confinement around the reinforcing bar was strong enough to prevent the splitting failure.

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Aggregates are continuously measured by volume in a continuous mixer. For controlling and determining the quantities of fine and coarse aggregates, devices such as counters and cut gates are employed. This paper presents the hatching accuracy of aggregates in the continuous mixer. A residual aggregate in the container and the operation of cut gate in an aggregate feeder of the continuous mixer do scarcely affect the quantity of aggregate and the accuracy in measuring and dispensing aggregate is within the required tolerances. With one measuring and dispensing equipment, coarse aggregates of maximum size with 40mm can be dispensed within ±3 percent of the amount required. The effects of moisture content and bulking factor of the fine aggregate, and grading of the fine and coarse aggregates on the quantities of aggregates supplied by the continuous mixer are also experimented.

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This study concerns the development of an efficient superplasticizing apparatus capable of simultaneously measuring, introducing, and mixing superplasticizer with the aims of rationalizing and systematizing the superplasticization process which poses the greatest obstacle to the wide use of superplasticized concrete. The superplasticizing performance and the applicability to actual projects of the apparatus developed are examined. As a result, the conclusion is drawn that the superplasticizing apparatus developed not only simplifies and speeds up superplasticization operations compared with existing methods, but is also an extremely useful device making possible reduction in manpower requirements and prevention of pollution.

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The purpose of this study is to examine the confinement effects of supplementary ties in reinforced concrete columns. 16 short tied columns are tested. The supplementary ties used have 180° hooks at both ends or at one end. In the two test specimens the tie with 180° hooks at both ends are engaged with longitudinal steel bars and in the other test specimens the ties are engaged with a perimeter tie. The test specimens are subjected to monotonic and cyclic loading. Based on the test results, the stress-strain curves of confined core concrete are obtained and the results are compared with the model which has been proposed by the authors. It is concluded that the authors' model on the stress-strain curves of confined core concrete is valid for the confinement effects of supplementary ties.

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