In this study, the effects of mixing several stone powders to the RCD concrete on the VC value and the compressive strength were investigated. The most effective mixing ratio of stone powders resulted in decrease of the VC value and increase of the concrete strength. Then, the factors increasing the RCD concrete strength in the presence of fine powders were diccussed.

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An experimental study is carried out for three consective years on volcanic acid rain effect on concrete specimens with and without cracks. Also at the same time the effective protection for coating material are investigated. And the following results are obtained; (1) The acid rain causes yellowish coloring to the surface of concrete. (2) Although the acid rain do not causes neutralization but accelerates the corrosion of rebar. (3) There's a high probability that the acid rain causes surface deterioration to the coating materials. (4) When sutaible coating material is used the surface deterioration of concrete can be prevented effectively.

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The present study proposes a bond-based analysis method of flexural deformation of reinforced concrete members subjected to sustained pure bending. The basic bond equations are formulated based on bond stress-slip relationship taking into account creep and drying shrinkage of concrete as well as creep of bond. The curvature due to drying shrinkage restrained by reinforcement is derived in the analysis. The validity of the analysis is demonstrated by comparing computed and experimental curvatures, strain of concrete in compression zone, tension reinforcement strain, bond stress and so on. The effects of creep and drying shrinkage of concrete and relaxation of bond stress on long-term deformation is investigated numerically.

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Mass concrete structures, especially having high strength concrete tends to occurs cracks in the early age and rather precise creep properties in the early age for these structures are required for the analysis. The tension creep properties in the early age are largely affected by the hydration amount, this effect have not been evaluated in the previous research. In the present research a creep equation for the concrete with young age has been proposed which can evaluates the factor of the hydration amount.

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The author reviewed the significance of numerical formula concerning the constitutions of grading requirements for graded coarse aggregate. Exponent values of Talbot's formula were calculated from the averages of various grading limits specified in both the JSCE and ASTM standards. The exponents that might be a basis for building up the standards' requirements are found counted on being larger than 1/2. It is also able to explain with the equation thus established that the grading requirements shall be more in large sizes and less in small sizes than Talbot's standard gradings modified from his original formula having the exponent of 1/2. Rules are found how to specify the points of sieves that limit the ranges of grading and how to choose the ranges of grading in the standards. Adding new sieves of size considers a new systematic series of the test sieves to improve the relationship between the nominal maximum size and maximum size of aggregate.

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As a method of connecting two concrete-filled circular steel pipes, a simple sleeve joint in which a small diameter pipe is inserted with the specific length to a large diameter pipe with concrete filling the gap between two pipes has been proposed as an economical and effective joint system. Joint specimens with shear connectors on pipe faces as well as those using a base plate at the tail end of the inserted steel pipe were tested in order to investigate the effect of loading method and the ratio of larger pipe diameter to smaller one. The test results indicate that the loading method, cyclic or monotonic, has little effect on the load-defection curves up to maximum load and failure mechanism of the joint system changes with the increase of pipe diameter ratio. In this paper, a modified equation for calculating the ultimate strength is developed to encompass those of more general configuration than the equation prposed previously.

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Evaluation of accelerators, based on calcium sulfo-aluminate, on calcium aluminate, and on soluble inorganic is carried out. Quick setting property and strength development of mortar with the accelerators are examined by type and content of accelerator, water to cement ratio and temperature. Concerning the evaluation of quick setting, comparison is made on wet method and dry method. The use of an accelerator based on calcium sulfo-aluminate is found to achieve high strength development and show no disadvantage in long term strength development.

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Acoustic Emission (AE) was applied in order to ensure the safety of an arch dam under construction. AE was monitored during secondary cooling and grouting between dam blocks. Quantitative AE waveform analysis based on the moment tensor analysis was performed as well as conventional AE parameter measurement. Low frequency AE sensors (15kHz resonant) were employed to detect AE signals generated in the dam concrete. Twelve sensors were installed at the dam surface and four of them were mounted on the floor of an inspection gallery inside the dam blocks. Neither critical AE activity nor intense AE cluster was found during the AE monitoring. It was concluded that the dam was safe during the secondary cooling and the grouting.

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To make clear the relationship between flow behavior in the slump flow test and rheological coefficients of high-flow concrete, slump flow tests and sphere drag tests were carried out simultaneously, and then analytical research was made on the test results. As a result of this research, it was ascertained that a high mutual relation exists between reaching time in 250mm radius and plastic viscosity, η_pl, if slump flow is at least 600mm. Consequently, plastic viscosity, η_pl can be obtained by reaching time in 500mm flow in the slump flow test, if slump flow is at least 600mm.

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It has been observed that RC column subjected to reversed cyclic loading in orthogonal direction to eccentric moment accumulates large deformation in the direction of eccentric permanent moment through experimental work. This deformation exceeded the allowable value in design code. Analytical investigation based on 3D-fiber model has been performed to grasp the mechanism of this matter. It is verified that this behavior derives from advanced strain hardening of steel by eccentric axial forces and strongly relates to complex nonsymmetrical loading pass. This fact indicates 3D-dimensional approach is inevitable to check the residual displacement of RC piers. Moreover, it is also suggested the present design method can't possess accurate predictive value for seismic performance.

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The durability of highly expansive material for anchoring of continuous fiber reinforcement, FRP tendons, was investigated from the stand point of material by using accelerating tests and an exposure test, in which the highly expansive material was filled in a steel sleeve and attained expansive pressure. During the curried out tests, i. e. wet-dry, accelerated neutralization, freeze-thawing and exposure in out-door condition, the expansive pressure increased with time, similar to the standard curing condition and reach up to 80MPa within one year. The degradation of expansive material was observed from the end of the steel sleeve. However, the epoxy sealing can protect the ends. The reduction of effective fixing length was less than 1.0% in the case of the sleeve length longer than 200mm and was considered to be negligible. It became clear that the anchoring system with highly expansive material was stable for a long term.

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This paper presents re-formulation of RC constitutive model with quasi-orthogonal cracks from one which have been developed with a mark for highly exactness of RC behavior until now. The model aims at simplicity of numerical programming and necessary accuracy for applying to dynamic response analysis of RC structure. Though path dependant parameters of cracked concrete and reinforcing bar are reduced in the model, range of applicability and accuracy are almost same as before one. Applicability of RC model is verified by comparing wide-range experiments which are subjected to various stress paths on uniformly stress field, and which contains before used for past-verification and newly added in this verification.

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Path-dependant spatially averaged constitutive model for in-plane RC domain containing 4-way cracks is formulated. Through the composition of the active crack concept for 4-way cracks and RC constitutive model with quasi-orthogonal cracks, real behavior including crack open/close among multi-directional cracks is modeled. Experiment of RC shells including multiple cracks up to 4-way is conduct. Verification of the proposed model is examined with the cyclic shear loading test of RC shell which have uniformly stress state, and good performance for predicting stress-strain relation, generation of crack and switching of active crack is shown.

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Based on the experimental bond test of continuous fiber sheet (CF sheet) bonded on concrete, the constitutive model for simulating bonding and debonding behavior of sheet was proposed. The model considering of the bond stress -relative displacement relationships can exhibit pretty good simulation of the actual bond behavior of CF sheet on concrete in terms of the load-end displacement as well as the strain distribution in the sheet.

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Verification of the proposed RC constitutive model stiring multi-directional cracks up to 4-way is conducted on stress field of RC structure which has non-uniform and different stress paths on each point. RC nonlinear FEM analyses which are object of comparison with statically loaded shear wall test, international blind benchmark analysis of dynamic shaking test of 5 story shear wall building and comparison with test of scale-down models for real structures are carried out. Further analysis of multi-directional cracks on box-type shell structure which is subjected to multi-directional loading is examined. These results confirm good performance for predicting highly nonlinear behavior of RC structures, and also show fair applicability and future enhancement for structural analysis by FEM.

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This paper presents an estimation method of dynamic ductility of unbond prestressed concrete (PC) beam and prestressed reinforced concrete (PRC) beam under high speed loading. First, the static and high speed loading tests were performed in order to examine the elastic-plastic behaviors and ultimate limit state of bond and unbond PC and PRC beams, respectively. It is found that the ductilities of unbond PC and PRC beams are almost two times larger than those of bond PC and PRC beams under high speed loading. Second, a discrete model analysis method was developed for the estimation of dynamic ultimate limit states of bond and unbond PRC beams under high speed loading. The both values of dynamic load and ultimate deformation estimated by the proposed method are almost in good agreement with those obtained by the tests. Finally, the proposed dynamic analysis was applied to the estimation of dynamic ultimate deformations of prototype PRC beams.

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Water absorbed permeable pavements have a high ability to maintain low temperature during summer time. But if the pavement has the same characteristics like as summer, it is undesirable for an urban thermal environment in winter. Field observations for 3 kinds of permeable pavements and 3 kinds of ordinary asphalt pavements were prepared to evaluate an urban thermal environment in winter. At the results, thermal radiation and temperature at the surface of permeable pavement was similar to ordinary pavements because of low evaporation rate. Furthermore, surface temperature of ordinary pavements showed the value under the freezing point at the daybreak, while that of permeable pavements keep nearly 0°C. Heat balance of pavement was estimated by using heat capacity method in winter.

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This paper discusses quantitative evaluation of the particle dispersion effect of polycarboxylate-based superplasticizer, varying mixing time, since the particle dispersion effect of the superplasticizer is characterized with the ratio of flow area and funnel speed of the mortar of self-compacted concrete. The particle dispersing effect of the superplasticizer decreased when mixing time is extended in the case of water double mixing. Main reason for this is that specific surface area of cement particles increases as cement hydration is progressed by mixing. The particle dispersion effect of the superplasticizer is in proportion to the adsorption amount of superplasticizer per unit surface area of cement particle, not per unit weight of cement particle. It is able to clearly explain that due to steric hindrance effect polycarboxylate-based superplasticizer exhibits particle dispersing effect even if mixing time is varied.

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Firstly, non-linear dynamic analysis was carried out to consider the effect of the yield process of each member on seismic performance of RC 2-story viaduct. Then the method to estimate non-linear response based on static analysis and equal energy rule was examined. Comparing the results of static analysis and dynamic analysis, it was demonstrated that this method was accurate. Finally, the rational seismic design method of RC 2-story viaduct considering the yield process was proposed.

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More and more ready mixed concrete plants are puzzled by the disposal of returned concrete and concrete sludge. In present study, a recycling method of such waste is proposed as below. Sludge is thrown into the drum of a truck agitator in which returned concrete still remains, and then mixed by the rotation of drum. After mixing, the mixture is discharged. Hardened mixture is crashed and used as base course material of road. All of this procedure was imitated and the properties of the mixture were investigated in laboratory. The influence of sludge content, type of returned concrete and the water content of sludge etc. on the modified CBR of mixture was examined. The site test was also performed. All test results showed that this mixture is a good quality base material of road. Now this kind of material has been used as base course material in practical engineering.

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In this study, methods for estimating the long-term Ca leaching from mortar and the accompanying deterioration of mortar through Ca leaching were proposed. First, using a combination of electro-chemical accelerated test and diffusion test, a method to estimate the long-term leaching of Ca was established. Second, the deterioration of mortar upon leaching of Ca was experimentally investigated. From this, a method for estimating the long-tern deterioration of mortar was established. And lastly, the deterioration of mortar due to Ca leaching was compared to testing a 30-year old real structure. It was shown that the Ca leaching from mortar and the deterioration of mortar could be estimated up to the age of 30-40 years.

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The objective of this study is to make a proposal on an evaluation method of steel corrosion in concrete structures located in seashore environment. Corrosion tests, which changed concentration of chloride ion, cover thickness and relative humidity, were conducted for fourteen months. In the tests, the corrosion rates of reinforcements were measured by AC impedance method using embedded electrodes. An equation evaluating corrosion rates of reinforcement in concrete was proposed based on the test results. Using indicator for influence of rain, an evaluation method of corrosion in concrete structures located in seashore atmosphere was proposed. Evaluated corrosion of specimens, which exposed at near seashore in Okinawa showed comparatively good agreement with real corrosion.

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In the structural design of composite pavement with concrete pavement slab overlaid with asphalt surface course, it is very important to estimate temperature gradient in the concrete slab. The asphalt surface course reduces the temperature gradientin the concrete slab, resulting in the reduction of thermal stress of the concrete slab. In this study, this effect was investigated by the temperature measurement in model pavements and themal conductivity analysis. Based on the investigation, the relationship between the reduction effect and the asphalt thickness was derived for the structural design.

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This study focuses on reinforced concrete viaducts damaged by the 1995 Hyogoken-nambu earthquake and estimation of their multiple damage state probabilities by using damage probability matrix for the structural elements, e. g., superstructure, substructure and foundation. Based on the resulting damage probabilities, the authors propose an integrated method for evaluating both functional and social damage states of viaducts damaged by earthquakes. In addition, the proposed method is applied for prototype viaducts damaged by the earthquake and viaducts seismically reinforced to estimate the effects of the reinforcement.

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The physical understanding and the numerical simulation of the characteristics of R. C. columns have been the focus of intensive efforts. Structural systems which are subjected to any kind of loads become quite difficult to analyse rigorously in their original physical forms, especially when the degree of freedom becomes so large. So in this work, the Modified Lattice Model, which was previously modified by the authors in two dimensions, is extended to the three dimensions. The reinforced concrete column under pure torsion is chosen as a material subject to check the suggested model in 3-D. The applicability of the suggested model in 3-D is examined successfully in comparison with many existing experimental data.

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This paper presents a three-dimensional (3D) constitutive model for non-linear finite element (FE) analysis of reinforced concrete with special attention to cracked concrete. Post-cracking formulations derived from uni-axial tension are generalised to the spatially arbitrarily inclined cracks with multi-direction. Anisotropic concrete tension fracture and reinforcement mean yield levels of the spatially averaged RC-model in association with a 3D RC-zoning concept are discussed. The proposed model is verified by numerically simulating inherently 3D shear failure of RC members subjected to torsion and RC short columns loaded in multi-directional shear.

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The aim of this study is to substantiate of a versatile numerical tool for a rational performance evaluation of RC-columns strengthened by steel plate casing or carbon fibre wrappings. Three-dimensional constitutive models of reinforced concrete, carbon fibre sheets, structural steel and steel concrete interfaces to be employed in non-linear finite element analysis of the strengthened column system are formulated. Following the proposed models are verified by full structural analysis of columns subjected to axial, flexural and shear loading conditions. Subsequently, the effectiveness of steel casing and carbon fibre wrappings is studied in view of its mechanism.

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The purpose of this study was to develop a new method for obtaining diffusion, film and shrinkage coefficients of cement-based materials. These coefficients are required for the numerical simulation of the effect of shrinkage strain on the deformation of concrete structures using finite element method. An experimental approach for obtaining the relative humidity distribution in the specimen at arbitrary drying times and a numerical method for determining the material coefficients from the experimental data are proposed in this paper. Results show that this method can provide us with the diffusion coefficient not only as a function of moisture content but also as a function of relative humidity in cement-based materials.

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Airport pavement roughness is studied including both the subjective evaluation and digital simulation. Pilots' subjective evaluation on surface characteristics is clarified by questionnaires, which indicates that the roughness is one of the most highly influential factors on riding quality and safety. The response of aircraft motion to the longitudinal profiles of airport pavements when departing on runways and taxiing on taxiways was simulated using the program TAXI. The results indicate that the aircraft response varies not only with the surface characteristics (i. e., the amplitudes and wavelengths of the profile), but also with aircraft speed. Finally, roughness criteria for runways and taxiways are proposed.

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