In this paper, first of all, a finite element analysis of flexure concrete members strengthened with externally bonded FRP laminates is presented to make clear the mechanisms of shear stress transfer along FRP-concrete interface for different variables. Based on the results of numerical simulations, a test program is designed to verify the different reinforcing effects, the debonding and other failure behavior of FRP-strengthened beams involving the main parameters such as the number and the end placement of FRP laminates. Through the theoretical and experimental investigations, finally, an effective anchorage strategy is also proposed and demonstrated in the paper.

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An innovative continuous PC girder with large eccentric external tendons was developed for bridge structures. Experimental and analytical investigations were carried out on the flexural behavior of such girders in order to identify the design considerations of such girders. It was found that the structural performance of PC girders with large eccentric external tendons is improved compared with the conventional use of external tendons, by effective use of materials. In addition, considerable flexibility can be achieved in the design of cable layout to suite various site conditions. Further, the analytical methodology developed for external tendons can be extended for these girders as well.

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This paper presents the results of static and fatigue tests of RC beams strengthened with tensioned CFRP plate. This plate was fabricated by Pultrusion method with carbon fiber, which has a guaranteed tensile capacity of 234kN and elastic modulus of 150kN/mm². From this investigation, it is evident that the flexural capacity of RC beams strengthened with tensioned CFRP plate increased, when compared with that of the reference beam without strengthening, no matter how the beam was deteriorated. This was further enhanced by installing the intermediate anchoring device in the shear span of the beam, because the peeling of the plate was delayed. It is also evident that the fatigue life of RC beams was increased by using tensioned CRRP plates.

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The damage level of a reinforced concrete member which composes a structure becomes an index to evaluate the seismic performance of the structure. Therefore, the appropriate evaluation of the relations between the plastic deformation levels and the damage level of the member becomes necessary for reasonable seismic resistant design of the structures. In addition, it is necessary to evaluate quantitatively the ductility which represents the damage level. From this point of view, we carried out reversed cyclic loading tests using RC model columns with large deformational capacities and examined the influence of main parameters on the deformational capacities of the model columns. This paper presents quantitative evaluation of the ductility of RC column members.

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The present paper deals with shear strength degradation of reinforced concrete columns under repeated large deformation. In the first, a discussion focuses on a degradation model of shear strength accompanying large repeated deformation far beyond the yield point of the main reinforcement. The shear-degrading curve proposed by Priestley et al. is extended to a case of random deformation history of strong seismic actions. And we evaluated the degradation of shear strength during the dynamic random process of reinforced concrete columns to use the cumulative damage model.

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The purpose of this study is to estimate the characteristics of the concrete using the aggregate by mixing, for the effective utilization of low quality aggregate. In this study, concretes using various low quality aggregates by mixing with high-quality aggregates, such as slag aggregate were tested. The type of aggregate and mixing rate were different each other. The specimens of such mixed aggregate concretes were produced, and fresh properties, strength characteristic, drying shrinkage and resistance of freezing and thawing were measured. In addition, the basic examination was carried out on the estimation method of characteristics of the mixed aggregate concrete from the quality of the aggregates.

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In order to establish a rational flexural strengthening method for exist RC members using FRP sheet, load carry response of the RC beams and sheet debonding behavior were experimentally discussed taking cross sectional shape of beam, main-rebar ratio, sheet-volume ratio, shear-span ratio, sheet material and loading type as valiables. And based on these experimental results and other published experimental data, empirical prediction equations for failure mode of the RC beams were proposed and an applicability of the criterion for sheet debonding derived based on the fracture energy concept published by JSCE was also discussed.

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The influence of gypsum and limestone powder on autogenous shrinkage of high-flow concrete made with ground granulated blast-furnace slag (BFS) were investigated. Gypsum or limestone powder was added to BFS. Addition of gypsum reduced autogenous shrinkage strain and improved the resistance to cracking due to autogenous shrinkage strain. It was suggested that the increase of the capillary pore volume due to the addition of gypsum related to the reduction of autogenous shrinkage. Addition of limestone powder reduced autogenous shrinkage strain and improved the resistance to cracking due to autogenous shrinkage strain at early ages, but autogenous shrinkage kept increasing at long ages with addition of limestone powder. It was suggested that the reaction of limestone powder caused the increase of autogenous shrinkage at long ages.

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The falling of concrete fragments from concrete structures has become a matter of great concern nowadays. In this study, concrete cover, carbonation depth, degree of corrosion, etc. were investigated in concrete structures whose concrete fragments had been fallen, such as railway viaducts, over-road bridges, over bridges.
Through the analysis of investigated factors, it was found that concrete cover, uncarbonated concrete cover, and rainwater/leaked water had a large influence on the falling of concrete fragments and steel corrosion.

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For the purpose to reduce the surface void of powder type self-compacting concrete, the effects of air content and fluidity, the types of form release agent are discussed in this paper.
Generally, the high-range water-reducing agents (SP) are classified for two types to adjust the air content. One of them is a type to annex the air entraining agent for Naphthalene type of SP, and anothor one is a type to annex the deformer agent for Poly-carboxylic acid type of SP.
The behavior of sinking coarse aggregate and rising air void were explained by the equilibrium of the forces of buoyancy, gravity, and fluidity resistance. Coarse aggregate and internal void is assumed a spherical solid body. The fluidity resistance of mortar is expressed by theological constants (yield value and plastic viscosity).
And, the separation of surface void from the form is showen to be possible to explain from the equilibrium of abovementioned force and adhesion to the form.

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The finite element model for bond between the reinforcement and the surrounding concrete was newly proposed. The bond characteristics were expressed as the isoparametric quadratic linear element and it was based on the non-linear bond stress-slip relationship. Two-dimensional finite element analysis on the pull-out test was carried out by the use of this model and comparisons were made with test results. The difference of the bond characteristics between two kinds of fiber reinforced plastic rods, i. e. twisted carbon fiber rod and braided aramid fiber rod has been numerically presented.

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Shear strength of reinforced concrete (RC) beams without shear reinforcement is experimentally investigated, in which compressive strength and effective depth are adopted as major factors. The experiment shows that the size effect of high strength concrete (HSC) beams is more significant than that of normal strength concrete beams, and the nominal shear stress normalized by concrete tensile strength at diagonal cracking is proportional to the -1/2 power of the ratio of effective depth to characteristic length. Based on this relationship a new empirical equation for calculating the shear strength of RC beams without shear reinforcement made of HSC with compressive strength of 80-125N/mm² is proposed.

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The seismic design codes for concrete structures were revised in several organizations after Hyogo-ken Nanbu earthquake. To aim at a performance based seismic design for reinforced concrete columns, we proposed deformation limit points related to damage levels taking restorability into account and a method of evaluating the deformation capacity of each limit point.
In this paper, deformation limit points of the cast-in-place reinforced concrete pile are defined and a method of evaluating the deformation capacity of each limit point in consideration of the section shape, the construction condition and the axial load is proposed based on the method for reinforced concrete columns.

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As a rapid chloride permeability test, the steady state migration test has been applied to evaluate the chloride ingress into fly ash concrete. It was found that the migration coefficient was obtained from the migration test within 2 to 3 weeks and represented the ranking on chloride ingress into fly ash concrete. Fly ash concrete showed an excellent resistivity against chloride ingress as the fly ash contents increased. This has been proved from both the migration test and along-term exposure test. In addition, the migration coefficients appeared to be used for the prediction of chloride profile in concrete with a proper bounding equation.

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This paper presents the experimental results on shear deformation of concrete beams with shear reinforcement, which was measured by laser speckle method. The results indicate that besides flexural deformation the significant amount of shear deformation occurred after shear cracking, which was caused by the localized shear deformation along shear cracks. Based on the experimental results, a rather simple mechanical model for prediction of the deformation is proposed. The model consists of a truss model that calculates the shear deformation and a modified Branson's model with the tension shift concept to calculate the flexural deformation. The model can predict the experimental results well.

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