In order to determine the limit of time interval for placing concrete on consolidated fresh concrete to prevent cold joints, which impair water tightness and durability of concrete structures, laboratory experiments were conducted on the durability between lower and upper layers. Concrete mixtures with ordinary portland cement and eco-cement were tested for accelerated carbonation on specimens with the time intervals up to 6 hours for placing upper concrete on consolidated lower concrete. The test results indicated that the depth of carbonation of the ordinary portland cement was deeper than the eco-cement, and carbonation of concrete joints were faster and deeper than the ordinary placed concrete.

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The reaction rates of C₃S, C₂S and fly ash were examined by proposed XRD method to investigate the strength developing mechanism of fly ash concrete. The strength development of fly ash mortar was examined by specimens and estimated with the reaction rates of C₃S, C₂S and fly ash by proposed method in this paper. The following observations are made: (1) the larger of surface area of cement, the more of hydration degrees; (2) the pozzolanic reaction degree of fly ash correlates with the calcium hydroxide, is approximately in proportion to the account of calcium hydroxide, and influenced by the liquation of calcium hydroxide; (3) when adding fly ash, the hydration of C₂S appears to be retarded, though it has little apparently effect on the hydration of C₃S.

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The purpose of this study is to establish evaluation method of workability for plastering materials. In this paper, we attempted to develop an inclined blades rotational rheometer in order to evaluate workability of plastering materials. And we investigated the appropriate method to evaluate workability on this apparatus, such as measurement method and analysis method.
As a result, it was found that the measurement conditions and the sample characteristics were major factors to influence the results of measurements. And inclined blades rotational rheometer could evaluate the viscosity and consistency of samples.

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The solar reflective performance of several retroreflective materials are evaluated by outdoor measurements. Their reflectances were derived from the quantity of heat energy received, which were calculated from temperature data. By correcting the measured data to fit the reflectivities of several non-retroreflective materials, the value of retroreflective component can be determined with an accuracy of about 1 percent, irrespective of measurement date. The measured retroreflective components are 5 and 13 percent for the bead-embedded type, 18 percent for the capsule-lens type, and 24 and 30 percent for the prism-array type.

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There are about 10 million existing non-conforming wooden houses today in Japan, and upgrading the seismic performance of such houses is essential for disaster mitigation. However, most of them remain untouched because of large expenditure for upgrading for both the owners and society. The owners have to spend about 1.1 million yens on average to satisfy the current design requirement. In Aichi prefecture alone, it would cost about one trillion yens, which is more than 1/3 of the annual budget, to upgrade all of them. In order to implement the upgrading of existing non-conforming wooden houses more efficiently, this paper investigates the alternative strategies for upgrading. The seismic risks of wooden houses as a whole in Aichi prefecture is estimated and then the effective target level for upgrading is discussed from the viewpoint of both economic loss and the number of fatalities.

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Ground motion attenuation relationships for spectral acceleration have been developed in Japan. Although these prediction models can usually provide a mean value and a standard deviation for each specified period, they do not characterize covariance property of spectral acceleration between two different periods. This leads to less accurate prediction of response of structural systems such as multi-degree-of-freedom systems and nonlinear systems. Some studies have paid attention to this shortcoming and tried to model the correlation of spectral accelerations by statistical method based on the small number of records. In the present paper, a large amount of ground motion records, which were observed from the recent earthquakes by K-NET and KiK-NET, were used in the covariance analysis. The covariance structure of two spectral values were investigated through principal component analysis. The covariance characteristics were fully investigated by examining the effects of the different source, path and soil conditions. And response spectra are simulated using principal components as an application of principal component analysis.

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This paper proposes a general method based on equivalent linearization technique using results of static pushover analysis with three dimensional frame model to predict seismic peak responses of steel structures with hysteretic dampers subjected to earthquakes. In this method, the equivalent damping coefficient at a given displacement is obtained by averaging damping coefficients of stationary vibration at displacement amplitude up to that displacement level. Time history response analyses were conducted to ensure accuracy of this method.

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Attenuation relations of horizontal and vertical ground motions for P wave, S wave, and all duration are developed using strong motion records of 34 crustal earthquakes in Japan. The relations are for peak ground acceleration (PGA), peak ground velocity, and 5 % damped acceleration response spectrum (SA) for radial, transverse, and vertical components. The regression coefficients show that reverse and oblique faults generate about 1.2 times stronger ground motions in a short period range than strike-slip faults. The three-component attenuation relation of PGA for P wave approaches each other as the distance is longer due to scattering effect, although the PGA of vertical component is largest and the transverse component is smallest in the close distance. For S wave or all duration, the attenuation relation of PGV for transverse components is about 1.2 times larger than that for radial components in the case of strike-slip faults. The attenuation relations of PGA and SA in a short period range for reverse and oblique faults in the close distance significantly larger than previous attenuation relations derived using horizontal and vertical components of S wave or all duration in Japan.

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In designing high-rise buildings, their seismic performances have been evaluated mainly in terms of maximum values of seismic responses such as story drifts and ductility factors obtained by time history analyses. When seismic actions containing long period components are concerned, cumulative response values including plastic deformations and/or plastic strain energy responses should be highlighted in addition because the durations of the ground motions are much longer.
Results of a series of time history response analyses of a high-rise building with steel structures for seismic actions with long-period components are shown in this paper. Based on the results, a method for evaluating seismic performances by selecting both the maximum and cumulative responses as the criteria is proposed adopting energy-balance based earthquake resistant design procedure.

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Collapse behavior of spatial rigid steel frame while vertical load at one place of the beam continues to increase gradually is investigated experimentally and numerically. The spatial frame consists of four columns and four beams. Lateral buckling of the H-shaped beam induced the collapse of frame. The tips of both square tube columns supporting the beam were drawn inward. The center of the beam was twisted and at the portion the plastic hinge was formed by weak axis bending. The torsion or sway behavior of frame was hardly observed in this study. The experimental results of small steel frames are illustrated that the numerical prediction by the elasto-plastic beam-column FEM developed by the authors has adequate precision.

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Numerous form-finding methods have been proposed for tension structures. While these methods are satisfyingly effective they require some special experiences or techniques for practical applications. This paper introduces the application of the generalized steepest descent method to finding minimal surfaces putting stress on its simple numerical concept. We also apply the method to solve the minimal surface with constraint conditions, which will be proved as a great help to improve the shape of membrane surface for architectural purposes. Soap film tests are illustrated to show the plausibility of the numerical results. Some remarks about the solution surface are also discussed.

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A method of driving wedge test was proposed in order to qualify the effect of reinforcement on splitting strength of timber. The wedge was quasi-statically driven into timber in its longitudinal direction by structural testing machine, during which the load and displacement were measured until splitting failure. Japanese cedar was employed for the substrate. Eleven sorts of reinforcements, i.e., plywood, rubber plate, steel sheet, punched aluminum plate, PVC sheet, jute, steel wire cloth, glass fiber cloth, carbon fiber cloth, carbon fiber felt, and polyester fiber cloth, were tested. They were attached to the substrate with three types of adhesives, i.e., epoxy resin, poly vinylacetate emulsion, and cyanoacrylate adhesives. The driving wedge test revealed the relationships between the strength of reinforcement and the load of splitting. A high correlation between splitting strength and driving displacement was observed. These results suggest that the simple test method provides consistent data on the splitting behavior of reinforced timber.

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A new technique using high level prestressing to construct a rigid joint between the column and beam of timber frames is proposed in this paper. Two timber substructure specimens, two-third scale models possessing the moment-resisting connections, were tested. The connections were constructed using prestressing bars, bent flat steel bars like a U-shape bar, high-strength bars, and thick square washers. The bent flat steel bars were bonded with epoxy resin glue to both the top zones and bottom zones at the beam section with flexure to strengthen the flexural tension in the beam subjected to moment. The high-strength bars were also bonded with a beam-column joint to resist the local bearing stress due to the flexural compression zone in the beam.
The specimens were subjected to reversed cyclic loading in accordance with a prescribed displacement history. The connections tested exceeded the performance of previous other connections, in terms of stiffness, strength and energy dissipation. In particular, the stiffness of the joint functioned as well as the rigid joint of a reinforced concrete frame. A model is proposed in this paper to predict the envelop curve of the idealized moment-rotation angle relationship. Comparisons between experimental and theoretical values were found to be reasonably accurate.

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Ten types of single shear screwed joints and nailed joints with different diameters, lengths, and side members were subjected to the monotonic and reversed cyclic loading. Test results were compared with the yield capacity and load-carrying capacity calculated by Yield Theory using the embedding test results of main and side members and the bending tests results of nails and screws. The calculated yield capacity and load-carrying capacity by Yield Theory showed good agreement with the experimental results. It was proved that Yield Theory is applicable to determining the allowable strength of screwed joints.

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We have developed the new connecting system using bamboo connector and adhesive. In this study, we try to improve the strength performance of the bamboo connector. The densified technique is adopted to produce to obtain high strength performance of bamboo connector in the production process.
The various kinds of tests of the densified bamboo and the joint with the densified bamboo connector were carried out to obtain the strength characteristics. The denified bamboo connector has very high strength performance for tension equivalent to that of steel connector. And the shear performance of bamboo connector is improved markedly by densified technique.

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The purpose of this paper is to understand elasto-plastic wind response characteristics of detached timber buildings with visco-elastic dampers that began to spread recently. The following approach is employed in this study. 1) Loading experiments acting long-duration random waves such as wind forces on a timber-frame wall with the dampers are conducted to examine their dynamic behavior. 2) Accuracy of time history behavior analysis of the wall is verified by comparing their results with the experiment results. 3) Time history wind response analyses with single degree of freedom models of the buildings are carried out to examine their characteristics. Furthermore, elastic response analyses and earthquake response analyses are carried out, then the wind response characteristics are set out by comparing each other.

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A new seismic retrofitting technique using compressive bracings for existing piloti-type reinforced concrete (R/C) frames has been proposed. The bracing is composed of steel pipes filled with high-strength mortar with its ends being able to resist only compressive force. This makes carrying out seismic retrofit easier, lowers the cost, and also minimizes the time spent.
A model is proposed in this paper to predict the envelop curve of lateral load versus story drift angle in the strengthened story after employing the compressive bracings. Calculations are presented to predict the axial stiffness and axial strength of the bracing, as well as the bearing strength and the partial bearing stiffness of the beams jointed to the bracing. Comparison between the experimental and theoretical values shows that the theoretical values predict the experimental values reasonably accurate.

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The world largest three-dimensional earthquake simulator, E-Defense, has been operated and available for shake table tests since January 2005. A five-year national project on seismic safety of urban areas, so-called DaiDaiToku project, started from 2002 in Japan. As a part of the project, seismic performance of reinforced concrete (RC) buildings were investigated through full-scale shake table tests at E-Defense in 2005 and 2006. The second phase tests were conducted for two three-story school buildings from September to November 2006. One was a bare RC specimen simulating an old and non-ductile school building with short columns, while the other was a retrofit specimen, which was constructed in the same design and strengthened with attached steel braces. The two specimens were constructed on the concrete flat slab base with construction joint simulating spread foundation, where sway and uplifting behavior would occur in seismic response of the shake table test. An obvious low level of input and damage to the building structures was verified experimentally, which was owing to the base slip behavior under an extreme earthquake motion. The plan, procedure and results of the full-scale shake table test on the first bare RC specimen are reported in this paper.

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Mechanical anchorage has been developed as an answer to bent-anchorage problems recently, and the authors have proposed the design criteria on reinforcement detailing of R/C exterior beam-column joint. In this paper, the application of highstrength material is studied through various experiments, in which compressive strength of concrete, the effect of anchoragelength of beam reinforcement, depth of column, and the quantity of shear reinforcement in beam-column joint, are examined. Consequently, the authors clarify that proposed design formula can be applied for estimation of anchorage strength of beam reinforcement and shear strength of beam-column joint, as well as design criteria on structural performance of R/C exterior beam-column joint.

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A proposal for the business continuity was contributed, that a steel-frame building is to be maintained in an elastic state during an earthquake. Nonstructural members which had not be evaluated as a proof stress, sometimes influence the seismic performance of buildings. The shear histories of nonstructural members were grasped by the frame experiments with the nonstructural members. And the response analysis was carried out, that was assumed the steel-frame thermal power station building just above the focus of a M6.9 earthquake, considering the shear histories of nonstructural members. The RC nonstructural wall shows high first modulus of elasticity and brittleness. And it is confirmed that the steel structural members of the thermal power station building which would be thought to show plasticity, approximately fitted into the elastic state by considering the RC nonstructural walls.

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A significant amount of research has been done in order to evaluate and improve the seismic performance of the lateral load resisting system in building structures; however, there still exists a need to study the behavior of non-structural systems during an earthquake. In order to address this issue, shaking table tests were performed to look at the behavior of non-structural gypsum board partition walls typically found in steel frame structures. Both a traditional Japanese hanging ceiling system and a seismically designed hanging ceiling system were also studied. The results suggested that the non-structural partition walls undergo a rocking behavior when perpendicular walls are framed into them. In general, stiffness and damping values were large enough to affect the overall behavior of a structure. Both types of hanging ceiling systems sustained only minimal damage and performed as designed. However, the seismically designed ceiling system underwent large accelerations due to pounding with the partition walls at drift levels greater than 1/66 radians.

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In order to prevent out-of-plane buckling of buckling-restrained brace, its connections must have enough out-of-plane stiffness and be kept elastic. This paper deals with out-of-plane stiffness and yield strength of buckling-restrained brace's connection whose section is cruciform. Firstly, methods of calculating both out-of-plane stiffness and yield strength of connection are proposed by means of RBSM. And secondly, experimental verifications to load connection specimens were conducted. As a result, it is clarified that out-of-plane stiffness is very small if fin-stiffener is not connected to beam-flange. Therefore, it is recommended that fin-stiffener should be welded to beam-flange to satisfy required out-of-plane stiffness and yield strength.

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H-section braces are widely used for seismic-proof elements in various kinds of structures. However, when they receive the cyclic loading beyond the expected seismic loads, they cause not only overall-buckling, but local buckling. It is known that such local buckling cause stress concentration within limited zones, and easily lead to the fracture of the member itself. Various hysteretic loop models for such braces have been proposed and used for timehistory analysis, however, it is not easy to predict the point of the fracture, their cumulative deformation capacity and energy dissipation capacity until the fracture. In this paper, cyclic loading tests on various H-section braces are carried out, and their fracture mechanism, relationship between the slenderness ratios and width-thickness ratios are researched. Their strain concentration mechanism is discussed through various analyses, followed by proposing easy evaluation method of their cumulative deformation capacity.

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This report deals with the parametric analysis of elastic shear buckling done by F.E.M. program in order to evaluate shear buckling behavior of rectangular corrugate plates accurately. The results calculated by F.E.M. program are compared with those given by existing formula and calculated by energy method analysis and the differences between rectangular corrugate plates and anisotropic plates are examined. Furthermore, using ratio of the moment of inertia, the influences of cross-sectional shapes and boundary conditions of rectangular corrugate plates are understood in some degree, and new approximate formulas to evaluate the elastic buckling strength are suggested.

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