A method for evaluating seismic damage of reinforced concrete piers is proposed on based on the energy concept. The energy dissipation capability of ten reinforced concrete pier models was evaluated from load-displacement hysteresis loops. Effect of the number of loading cycles, shear span ratio, hoop reinforcement ratio and axial compressive stress on the energy dissipation capability was investigated.
An empirical equation to estimate the energy dissipation capability was proposed. This provides a reasonable estimation for the energy dissipation capability of the test specimens.

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The evaluation method of lifetime risk in reinforced concrete structure is proposed. In the earthquake risk analysis, historical earthquake data are efficiently taken into account. A new damage index is defined in which accumulative damage is taken into consideration for RC member. Then new evaluation method of lifetime risk in RC member is proposed on the basis of damage probabililty matrix. As a result, it is clarified that current seismic design method does not necessarily provide sufficient safety during the lifetime of RC structure.

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During certain types of construction work, many vertical joints between the slurry wall panels and composite wall joints are enclosed by slurry wall member. In-plane ultimate shear strength and out-plane ultimate bending shear strength of slurry wall member with vertical joints and out-plane ultimate bending shear strength of composite wall member with joints were examined experimentally. The calculation method for design shear capacity, incorporating a certain safety factor, is then proposed.

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Heat conduction and thermal stress problems of reinforced concrete members and steel-concrete composite members are discussed based on the experimental and theoretical points of view under external high temperature loading condition such as 1000°C. Finite element analysis using an extended embedded model for reinforcements is presented to solve the three dimensional thermal problems of these members. In addition, the heat conductivity and Young's modulus of concrete are measured under such high temperature.

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The purpose of this study is to estimate of the rate of steel corrosion in the carbonated mortar. An accelerated carbonation test and a cyclic accelerated carbonation and water-spray test were performed with the mortar specimens embedded steel bar. The amount of steel corrosion, electro-chemical properties, -potential and corrosion current of steel bar, resistivity of mortar-, were measured.
The corrosion rate of steel bar depends on the depth of carbonation, resistivity of mortar and diffusivity of oxygen. And theresistivity depends on the degree of hydration and carbonation, the water content of moratr and temperature.
Based on these results, the corrosion model was proposed. The amount of steel bar in mortar due to carbonation can be predicted by using this model.

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This study aims to reduce unit powder content of high fluidity concrete by controlling powder's particle size distribution. In this paper, the ranges of viscosity and yield value of mortar to be part of concrete, which satisfy the high fluidity, non-segregating property and passability between steel bars, were clarified. And the physical characters of powder, which can satisfy the ranges with the minimum unit powder content, were clarified. Based on the results, new cementitious powder which can produce high fluidity concrete with low unit powder content was presented.

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To use a buried joint on roadway viaduct is one of the effective methods for putting a jointless system to practical use. The grid panel type buried joint, which contains steel honeycomb grid panel and sliding sheets, has the advantage of being applied to long spanned bridges. This advantage is caused by strain dispersion function which is the most remarkable point of the buried joint. This type buried joint, however, has been developed from only experiences or results of test installation. Therefore degree of the effect and basic characteristics about strain dispersion function are not proved.
In this paper, strain dispersion function of this type buried joint is evaluated by laboratory experiments, and effects of grid panel and sliding sheets are investigated respectively. From the result of experiments, it is suggested that the friction between sliding sheets considerably affects strain dispersion function. So relation between strain dispersion function and the friction is also discussed with simply analytical study. It is concluded that grid panel is necessary element for this type buried joint and material characteristics of composite mixture which consists of asphalt mixture and grid panel is important for strain dispersion function.

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In the design of concrete pavement, warping stresses caused by temperature differences of concrete slab should be calculated at the transverse joint edge. However, any such an equation has been not developed in the past. Accordingly, the authors developed a warping stress equation based on the stress analysis by finite element method (FEM). In this FEM analysis, concrete pavement and its transverse joint were expressed by means of a thin plate-Winkler foundation model and a spring joint model, respectively. Multi-regression analysis was applied to the results of the FEM numerical calculations, and consequently, a warping stress equation was obtained. After the comparison between calculated results of the proposed equation and the warping stress equations developed in the past, it was confirmed that the equation was valid and practical.

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The main tower of the Tsurumi Tsubasa Bridge consists of the steel shell structure for the upper part and the steel reinforced concrete structure for the lower part. To connect these two parts, a new type structure has been developed on the basis of experimental study. The shear basic test of the connection reinforcement was carried out. Then the structural model test and the large-scale structural model test on the connecting part of the main tower were carried out. It was recognized that the proposed connecting structure had enough load carrying capacity and deformation characteristic. Besides, the estimating method of shear strength and deformation characteristic of the connecting part was obtained.
Consequently, the proposed connecting structure has been applied successfully at the Tsurumi Tsubasa Bridge of Metropolitan Expressway.

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This paper reports the compactibility and mix design method of extremely dry concrete. The consolidation curves of extremely dry concretes are tested, and consolidatin function, which is the relationship betwen the solid volume ratio of concrete and the consolidaion effort, is discussed. The consolidation function of a certain concrete is dependent on consolidation effort, if the acceleration of vibration is greater than the critical magnitude of about 2.5G. The compactive characters are evaluated by the function and four indices derived from it. The effects of mix proportion and the characters of fine aggregate are discussed, and the design method of the concrete with high compactibility is proposed.

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In this paper, the method based on the poly-linear approximation analysis is investigated to determine tension softening diagrams of concrete. This method belongs to the back analysis through the finite element method using the fictitious crack model and needs only load-displacement curves of concrete from experiments. By this method, complicated poly-linear tension softening diagrams can be determined from test results on load-displacement curves. The tension softening diagrams of three kinds of fiber reinforced concretes (fiber: aramid, vinylon and steel) are determined by this method. The flexural failure behavior of these fiber reinforced concretes is discussed.

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In order to establish the reliable cathodic protection system to prestressed concrete structures, this paper discussed hydrogen embrittlement of prestressing steel. Specimens used were 5mm-diameter prestressing wires and 9.3mm-diameter, 7-wire prestressing strands in concrete exposed to marine environment and hydrogen generation condition for 5.5 years. And then susceptibility to hydrogen embrittlement was performed with slow strain tensile test (SSRT).
As a result of SSRT and hydrogen thermal analysis, the influences of catholic polarization potential, environment around prestressing steel, stress and exposure period to hydrogen evolution condition were made clear. In addition, possibility of recovery of hydrogen embrittlement was also discussed.

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The punching shear strength of reinforced concrete slabs decreases when a load is applied near the free edge. In the JSCE Standard Specification for Design and Construction of Concrete Structures, the diminution of the strength is considered by shortening of the length of the critical section which resists to punching shear. This study reveals that the above method is insufficient to consider the effect of free edge based on the test of simply supported slabs with free edges. The method evaluating the ultimate shear strength in such case is discussed and two practical design methods are proposed; the method considering the shortening of the length of the critical section as well as the decrease of the punching shear strength per unit length of the critical section, and the method applying beam shear strength to the effective width of the slab.

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This paper aims to make it clear that relationship between size distribution of powders and rheological properties (yield value and viscosity) of mortar which have direct effects upon properties of high fluidity concrete. As the results of this study, they were found that yield value of mortar is influenced by n-value of the Rosin-Rammler which is the main factor of amount of excess water in mortar, and that vicosity of mortar is influenced by blaine surface area, which it is reason of the effect obtained by combining absorption of superplasticizer and thickness of water film.

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Two patterns of crack models have been observed depending on thickness of cover concrete; when the cover is thick, cracks propagate form reinforcements to concrete surface in the shortest path and when the cover is thin, cracks develop diagonally and cause a spalling off concrete. Governing equations which can explain the two crack patterns are presented based on elastic theory. The delimiting value of D/φ which distinguishes the pattens is found to be 3.0. φ is a diameter of reinforcement and D is 2t_p+φ where t_p is a thickness of cover concrete.
Galvanic corrosion tests and pressure tests due to Expansive Demolition Agent are also conducted on test specimens of D/φ=1.67, 3.0, 7.67, 11.0 and 20.0. The specimen of D/φ=1.67 results in a spalling off of concrete. For the other specimens, cracksruns along reinforcement vertically to the surface. From the experiments, it is observed that the distinct crack pattern appears whether D/φ is greater or less than 3.0. The observation shows a good agreement with the theoretically obtained delimiting value. Furthermore data obtained in situ shows a good agreement with proposed crack model, too.

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In the previous paper, we presented a network level pavement management system based on dynamic programming under the constraint of total budget during the analysis period. In this paper, the system was expanded to the case where annual budgets are constrained.

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Most of the available creep prediction models proposed by the different national building codes are valid only for concretes having compressive strengths not greater than 800kgf/cm² (80MPa). A rheological viscoelastic model is proposed for predicting the creep of normal- and high-strength concretes from their basic constituents, that are cement paste and aggregate. A parametric study is carried out to compare the creep functions calculated using CEB-FIP Model Code 1990 and ACI Committee 209 with those calculated using the proposed model as well as with the available experimental data. The comparison indicated that the proposed model can predict the creep of both normal- and high-strength concretes.

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This paper investigates pullout behavior of embedded deformed bars in concrete under coupled transverse shear arising at a crack of reinforced concrete. It was experimentally proven that the pullout capacity, which reaches yield of steel section at a crack under uniaxial tension, does not come up with full yielding of the critical section where the axial stress gets maximum, but the ultimate limit state is reached not at the RC crack plane but inside location in which induced curvature by shear slip of crack takes place. It is concluded under higher reinforcement ratio and/or flatter planes of concrete joints, coupling of pullout and transverse shear of steel at a crack cannot be ignored in structural analysis.

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This paper presents reversed cyclic models of coupled RC/soil system. The full path-dependent constitutive models of RC, soil and their interfacial zones which are installed in the FEM program WCOMR-SJ are explained. Consequently, RC/soil hysteresis damping and energy absorption are coherently taken into account with corresponding states of damage and plasticity regarding concrete and reinforcement. This computational tool was systematically verified through coupled RC/soil system subjected to static reversed cyclic loads. The nonlinear interaction of RC/soil system and induced damage of underground RC are investigated.

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In the present paper we propose a simple analytical model for fracture analysis of short fiber reinforced cementitious composites designed to undergo distributed multiple cracking prior to formation of a localized crack under tensile and shear loads. The composite in multiple cracking state is idealized as a homogenous and continuous material, with cracks being represented by cracking strain. A discrete crack model is used for localized cracks. The model is implemented into FEM code and experimental results are reproduced proving validity of the proposed model.

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The recently established Japanese design provision on the estimation of the load-carrying capacity of steel-fiber-reinforced concrete (SFRC) tunnel linings is based on the concept of fracture mechanics of concrete. Existence of a crack and stress transmission by fibers are considered in the estimation of the maximum resultant forces of the critical cross-section. In this study, the validity of the current design method is verified, and the possible improvements of the design method are proposed.

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