To understand the tehrmal stress generation mechanism of mass concrete, it is necesary to obtain a good agreement between analysis and observed data not only on stresses and strains but also deformation. For this purpose, thermal stress experiment was performed with five large scale specimens by changing effects of external restriction from concrete base. In this experiment, effect of external restriction can be adjusted by bond strength at construction joint and shape of concrete specimen which denoted by ratio of length and height (L/H). To show how simulate the experiment by the finite element method which is implemented the crack element model to express the behavior of joints and cracks, numerical parametric study was carried out. Consequently, spring stiffness of the crack element can be identified, and existence of different mechanism of thermal stress generation according to levels of external restriction was shown.

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Estimasion method for the strength of anchorbolted pedestal of bridge tower was experimentally investigated and formulae to calculate resisting load was proposed. The investigation also shows that it is nesessary to consider the sise effect in which the resisting load in this kind of structure is inversdly proportional to the square root of embedded length.
Moreover, it indicate that the commonly adopted method assuming 45 degree failure surface yields exaggerated resisting load.
Finally, an ivestigation was conducted on the resisting load caluclation method of the pedestal structure with reinfocement.

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This paper is concerned with the problem of a penney-shaped dislocation in elastic layers bonded on elastic half-space. Papkovich-Neuber functions are used for the analysis. The basic equations are expressed by a system of integral equations which can be numerically and approximately satisfied with the collocation of an integration parameter λ. Numerical treaments for some cases are carried out and several numerical results are given by graphical representation.

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This report describes a non destructive pavement structural evaluation method using the Falling Weight Deflectometer (FWD). Deflection indices which include deflection and shape factors are determined from deflection basin measured by the FWD. The multiple regression method is proposed to get seeds which are used for backcalculating layer's elastic moduli.
As a result, it takes less time to backcalculate elastic moduli.

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Many RC members are subjected to the parabolic bending moment distribution and liniar shear force distribution under the combined action of distributed load and concentrated loads. And they usually have some moment inflection points within the span. In this study, shear resisting behavior and shear capacity of this type of beams were examined based on the experimental results. Then, the calculating method of shear capacity of the beams was proposed, utilizing the “zone shear strength equation” which has been proposed by the author.

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It is described that numerical analysis with tension softening diagram is effective to discuss the size effect on modulus of rupture and the flexural failure behavior of steel fiber reinforced concrete (SFRC). It is shown that the tension softening diagram, which is determined by means of our modified J-integral based method, is valid and that the diagram can be improved through analysis. Load-displacement curves of SFRC beams (depth: 10, 20, 40cm) are simulated and the numerical results are in good accordance with the test results. Numerical analysis can fairly explain that the first peak load of SFRC beams depends on the matrix resistance and that the second peak load appears due to the fiber reinforcement.

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Models using neural network were applied to analyse the data obtained in rapid carbonation test and mixing of concrete. The models were compared with proposed empilical equations by other researchers, and study was made to find important factors which were not considered in the equations.
The results show that the models using neural network is effective both to estimate the experimental results and important factors much easier than conventional analysis. This shows that the neural network is valid for analysing the experimental data not only to estimate the values but also to find important factors governing the phenomenon.

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Results of length change measurement of early-age (8hr. to 14 days) concretes subjected to freezing and thawing cycles were examined for their relation to the freeze-thaw resistance of respective concrete. Water-cement ratio of concrete was fixed at either 45, 55 or 65%, while the air content was kept constant at 5.5%. The conventional method, in which a certain residual strain is employed as a reference value, was not necessarily adequate for the adequate evaluation of the freeze-thaw resistance of earlyage concrete. It was revealed that there existed a straight-line relation between the number of freeze-thaw cycles in a normal scale and the residual strain in a logarithmic scale in the region where the strain exceeded 100×10^-6. A factor which was derived from the gradient of the linear relation was found to have a close correlation with the conventional durability factor, regardless of the difference in the mix proportions, ages and curing conditions concrete.

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Displacement-controlled cyclic bending test is performed for reinforced concrete beams with different shearing span and stirrup ratio. Accumulative damage evaluation using the total dissipated energy, up to rupture, is investigated for the reinforced concrete beams.
These reinforced concrete beams are destroyed under cyclic loading due to the rupture of reinforcement in the beams. The accumulative dissipated energy up to rupture shows almost constant independent of loading displacement and deformation histories. The time for the beams to be destroyed due to cyclic bending moment can be evaluated by the accumulative dissipated energy.

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This paper clarifies a chemical structure of gel of sodium silicate grout examined using relaxation spectrum and an electron microscope. As a result, following chemical structures of grouts were estimated. A chemical structure of gel of grout used in organic liquid reactants consists of networks that form entanglements between short liner particles. Non-Alkaline silica-sol grout forms three dimensional networks which are partly crystalline. Ultra-Fine grain silica grout forms granular structure which combines coloidal -silica particles in three dimensions, . Also, this paper examines the relationships between grouts and the durability of the grouted sand strength used in this experiment.

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It is known that PC members reinforced with FRP as tendons show brittle failure in spite of the failure modes. The objective of this paper is to improve ductility of PC members reinforced with FRP as tendons. Compressive behavior of concrete confined with CFRP was investigated. It was confirmed that compressive stress-strain of confined concrete was greatly improved to ductile manner. PC members using CFRP as tendons and transverse CFRP to confine concrete were newly developed. Ductility of the PC members was greatly improved.

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Under triaxial stresses, the continuum fracture defined as the damaged elasticity of concrete was experimentally extracted. The volumetric elasticity was found not to be mechanically damaged even though the concrete subjected to lower confinement comes up to the higher nonlimearity in appearance. On the contrary, it was verified that the elasticity of concrete in shear is seriously deteriorated according to the internal shear stress intensityy expressed by the elastic strains. The concept of the internal stress, which is directly proportional to the elasicity, was adopted for evaluation of the stress intensity applied to non-damaged volume which retains the capacity to absorb the elastic strain energy. The fracture parameter, which indicates the loss of elastic strain energy in the mode of shear, was formulated in terms of the hysteresis of the internal hydrostatic stress to represent non-localized defects in space.

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The constitutive law for plasticity of damaged concrete was proposed under triaxial stresses. The plastic deformation was drawn from the entire nonlinearity and formulated in terms of the elastic strain, which is regarded as the indicator of the intermal stresses of damaged continuum. The progress of the plastic deviator (shear) was found not to be dependent on the confinement, but merely on the elastic deviator. On the contrary, the dilatancy, which is the growth of the volumetric plasticity associated with the shear one, was elucidated to be strongly influenced by the magnitude of confinement. The flow rule to regulate the plastic increment in shear was also proposed with respect to the updated elasticity. The model of plasticity of the damaged continuum was experimentally verified with regard to the plastic Poisson's effect theoretically derived under compression.

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The complete constitutive equations in the form of tangential stiffness matrix are derived from incorporation of the constitutive law of the continuum fracture with the one of plasticity. The triaxial stress states are the main concern of authors since the accomplished model is wished to be a crucial and universal tool of analysis for laterally confined RC columns with wider variety of geometry and dimension. The constitutive equation derived under triaxial stresses was proved to cover the plastic and fracturing aspects of concrete as well as Von-Mises type of plasticity serving as the model of steel in reinforced concrete. The authors validated the fitness of the model for the triaxial behaviors of concrete reported. The failure envelope was not utilized in formulation unlike the theory of plasticity.

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The paper contributes towards the development of a methodology capable of simplifying and unifying ultimate limit state design of structural concrete. It is shown that such a methodology could be based on the proposed concept of the compressive force path which, for the case of simply supported reinforced concrete beams, has been found to yield design solutions, not only significantly more economical, but also, safer than those obtained by using the methods recommended by current Code provisions. It is demonstrated that the proposed design method can easily be extended to apply for any type of skeletal structural concrete configuration which represents the structural elements between consecutive points of inflection being modelled as an “internal hinged support” effected by the provision of transverse reinforcement.

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Generally speaking, with regard to mechanical chracteristics of materials, modulus of elasticity is sensitive to variations in the ratio of crystalline and non-crystalline parts in the structure, while strength is comparatively insensitive to such variations. Meanwhile, the progress of alkali-silica reaction can be considered as being the process of the proportion of the non-crystalline part to the crystalline part increasing in ratio in the entire structure of the concrete. By taking advantage of such a property, it can be judged whether or not deterioration due to alkali-silica reaction has progressed in the structure from the results of measurements of compressive strengths and moduli of elasticity of cores taken from concrete members.

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