Concerns about cracking in concrete structures have grown in recent years. The cracking can be controlled very effectively by using a shrinkage-reducing agent to reduce the drying shrinkage of concrete. However, conventional shrinkage-reducing agents have some issues, such as difficulty in adjusting the concrete's air content and a significant decrease in freezing and thawing resistance. We conducted a feasibility study on a new shrinkage-reducing agent that reduces the shrinkage by retaining moisture in the concrete. This new shrinkage-reducing agent simultaneously reduces shrinkage and improves freezing and thawing resistance. Compared to conventional shrinkage-reducing agents, this new shrinkage-reducing agent provides superior concrete workability.

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The purpose of this study is technical development of automatic arc welding in narrow gap with 25 degree single bevel groove for cold formed SHS column to through diaphragm connection. In this paper, the range of conditions on the built-up welding and the first layer welding within the groove are investigated by the welding procedure tests. To the built-up welding, lower reinforcement bead, enough throat thickness and penetration depth are required. To the first layer welding, the remelting of built-up weld bead and preventing of hot crack are required. Finally the recommended range is shown.

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Weatherability of construction sealants was studied from the viewpoint of waterproofing. First, the outdoor exposure tests of 12 sealants were carried out for 10 years at Miyakojima, Choshi and Asahikawa in Japan, using the newly developed specimen which is able to reproduce wide range of sealing joint width in the same specimen. The joint width was moved once a month through exposure duration. The two kinds of cracking were observed such as shallow cracking on the surface of a bead and deep cracking at the close portion of it to the adhered face in the specimen. The depth of cracks was measured at the three positions of 0, 15 and 25% deformation rate in a specimen by a microscope and a taper gauge. Deep cracking is considered to be fatal rather than shallow surface cracking for waterproofing performance, and the weatherability estimation method of sealants was proposed.

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Thermal insulation materials for chimney pipes are concerned to deteriorate by freezing and thawing effect especially in cold areas.
In this research, airborne fibrous particles concentration was measured at indoor, inside of chimney pipes and outdoor around buildings which use asbestos containing thermal insulation materials for chimney pipes, and degree of deterioration of those materials was verified.
As a result, asbestos fibers were detected indoors of 2 buildings, inside of chimney pipes of 5 buildings and various degree of deterioration of thermal insulation materials for chimney pipes were examined.

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This paper deals with the development of composite cement concrete-filled-bamboo (CFB) comprising pulverized waste plasterboard (P-WPB: G), fly ash (F), ground granulated blast-furnace slag (GGBFS: S) and bamboo. The fundamental properties of the F-S-G paste with regard to fluidity, drying shrinkage and compressive strength were tested, and the influence of the replacement ratio of P-WPB was investigated. Using the optimum proportion of the F-S-G mixture, the properties of green concrete, such as compressive strength, Young's modulus, shrinkage strain and air permeability were tested. Furthermore, a counter measurement to decrease the autogenouse shrinkage was conducted. Finally, author proposed concrete-filled-bamboo (CFB) and investigated the effect of reinforcement with bamboo throughout the bending and compressive strength of CFB.

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In this study, we carried out outdoor exposure test of concrete specimens with coating materials for textured finishes including repair specification in order to make clear the deterioration of coating materials and aging of the protective effects on deterioration of reinforced concrete structure. These specimens were exposed to Ishikari, Tsukuba, Tokyo and Okinoerabu. According to the results, it was not observed the difference of deterioration in coating materials between primary specification and repair specification. The gloss retention was affected by coating material type. We proposed estimation methods on change of gloss retention, Cl- diffusion coefficient and CO₂ diffusion coefficient based on the test results.

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Epoxy floor coatings blistering sometimes occur when those are applied on concrete substrate. One of cause on this phenomenon was considered to be osmotic pressure owe to water in concrete. Recently in order to prevent epoxy floor coatings from blistering, some polymer cement mortar as underlayment material is often applied on concrete substrate, and epoxy floor coatings are applied on this underlayment one. But those polymer cement mortar is not effective in preventing epoxy floor coatings from blistering perfectly. So at first we have studied the relationship between epoxy floor coatings blistering and concrete substrate property. And on the base of those study consequence, we have developed new polymer cement mortar material to prevent epoxy floor coatings from blistering most perfectly. This material as underlayment was tested for adhesive strength to epoxy floor coatings, and performance of preventing epoxy floor coatings from blistering according to accelerating blistering test method. From the test results, their excellent performance is confirmed.

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This paper presents a design method for super high-rise structures with tuned dynamic mass systems. After the 1995 Southern Hyogo Prefecture Earthquake and the 2011 off the Pacific coast of Tohoku Earthquake, it becomes very important to design response control structures against two types of coherent earthquake ground motions such as long period waves and pulse waves. This paper discusses the performance of structures which are designed by making use of tuned dynamic mass systems against these ground motions having JMA seismic intensity scale 6 upper or 7.

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This study presents the verification of damage evaluation method based on the measurement of Relative Story Displacements (RSDs). The damage evaluation method is formulated to detect the damaged locations of structural elements and evaluate their damage degree based on the displacement loading analysis by the time histories of measured RSDs. In the evaluation process, the analytical technique is introduced to compensate for the measurement errors associated with the sensor properties. The monitoring accuracies are analyzed through the shaking table test of a full-scale 4-sotry steel building carried out at E-defense in Japan. The results indicate the effectiveness of the proposed damage evaluation method in its applications to the structural health monitoring system.

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The authors carried out basic studies on vibration control systems that utilize a rotating inertial mass damper (RIMD) concentrated in the lower stories of a building. In this paper, we adopted 2DOF systems with various damping devices installed in the first story, and compared their frequency transfer functions with optimum design parameters which can be determined by the fixed points theory. Even without a series connection spring, an installed RIMD is found to be able to achieve an effective tuning mass damper system, and to reduce the amplification ratio to the square root of that of the 2DOF system without a RIMD. With a series connection spring, the optimum mass and damping factor are found to increase according to the stiffness of the connection spring, and the amplification ratio decreases accordingly.

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The variations of the ground motion response spectra are examined by comparing pairs of ground motion records observed at the same site from two earthquakes with the same magnitude and hypocenter location. In the analysis, it is assumed that the variations of the spectral amplitude is composed of the between-events variations and the within-event variations (also called the intra-event variations and the inter-event variations), and evaluate the standard deviations of each variation.
The evaluation result of the logarithmic standard deviation of the total variations (σ) is about 0.35-0.45. And, the standard deviation of the between-events variations (σ_B) is about 0.2, and the standard deviation of the within-event variations (σ_W) is about 0.3-0.4. The σ_W decreases with increasing the distance. This distance dependence can be caused by the effects of scattering of seismic waves in the path.

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Scheme of computational morphogenesis for the shell structures with free curved surface is proposed, where the shape can be optimized for linear buckling load. In the proposed scheme, The problem in question has been mathematically formulated as linear buckling load factor maximization problem where coordinates of NURBS control points with respect to the shape of curved surface are adopted as design variables and Genetic Algorithm (GA) is utilized to solve this problem without any difficulties because no sensitivity analysis, in needed. Numerical examples are presented where the effectiveness of the proposed scheme and the structural characteristics is investigated.

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We study the dynamic response of high-rise steel buckling-restrained braced frames (BRBFs). Three BRBFs designed using different design base shear are subjected to two types of artificial ground motions: One is the long-period ground motion with peak value of 250 cm/s around a dominant period of 3 sec in the velocity response spectrum, expected to take place at Sannomaru site in Nagoya City. The other type is the design ground motion with constant velocity response spectrum of 100 cm/s in the long-period range. For the former type of ground motion, deformation concentrated to lower stories when the ground motion was amplified more than 1.3 times in the BRBF with the highest design base shear. For the later type of ground motions, the deformation concentration was observed when they were amplified more than 1.5 times in the BRBFs with lowest and middle design base shear. Care should be taken when the natural period of a BRBF is smaller than a dominant period of the long-period ground motion even when the design base shear is high. It should be emphasized that the deformation concentration was not observed when the post-yield story stiffness was positive, or when the p-delta effect was neglected.

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We propose an incremental analysis method with a model considering compressive strain inclined to the grain and friction in a mortise-tenon joint with dowel to examine the hysteresis characteristics of the joint subjected to cyclic loading. We introduced a concept of apparent shear stiffness based on the Coulomb's friction into constitutive law. The analysis method can evaluate cyclic hysteresis characteristics of the joint with constitutive law based on material tests. We performed a bending test of a T-type specimen composed with a beam and a column, and confirmed validity of the proposed analysis method.

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In designing superstructure of buildings, it is important to estimate the ultimate bearing capacity of the building foundation. The ultimate bearing capacity formula of foundation is specified in the guideline published by Architectural Institute of Japan for design of building foundation. The rigid plastic finite element method was developed by Tamura to estimate the ultimate bearing capacity of footing. The characteristic of this method is to employ few numerical parameters. It does not use the Poisson's ratio and the elastic modulus since it deals with the limit state directly by disregarding the deformation of building and ground. The rigid plastic constitutive equation proposed by Ohtsuka, which is displayed by the relationship between stress and strain rate, is employed in this paper. The strength parameters as cohesion, c and friction angle, φ are only employed. By performing a series of rigid plastic finite element analyses, the comparison of ultimate bearing capacity between the formula by Architectural Institute of Japan and the simulation results was conducted. Finally, the case study applied to the practical design was exhibited to show the applicability of numerical method to practice. In conclusion, it is clearly shown that the ultimate bearing formula is highly rational and the rigid plastic finite element method is effective to assess the ultimate bearing capacity of foundation.

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