Waste concrete fine powder that is residue after aggregates recycling of demolished concrete is disposed as a low material of value. We have developed the process of dividing waste concrete fine powder into a material by using acid. In this paper, the process of waste concrete fine powder was applied and the manufacturing process of recycled fine aggregate which does not discharge waste concrete fine powder was developed. And by using ultrasonic for this recycled-fine-aggregate process, it succeeded in the quality of recycled fine aggregate, and improvement in processing efficiency.

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Time dependent change of thermal expansion coefficient was observed in cement paste with W/B 0.40 whose binder was blast furnace slag cement. This time dependent change of thermal expansion coefficient could make a large amount of shrinkage as a thermal strain during temperature history emulating mass-concrete. In this contribution, control method for thermal expansion coefficient with artificial lightweight aggregate (ALA) was investigated in order to reduce the amount of thermal strain. As a result, saturated or partial saturated ALA could restrain the increment of thermal expansion coefficient compared to that of normal mortar with same W/B, and reduced thermal strain. Autogenous shrinkage of mortar with ALA was also reduced as known in an earlier study, however, greater part of reduction of total strain was result from reduction of thermal strain.

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Two technological problems on surface treatment of aluminum alloy building materials have been indicated. One is disuse of the chemical conversion reagent which contains chromium VI. The other is new application of powder coating that excludes organic solvent. In the Japanese construction industry fields, the application of the powder coating has not yet been popularized. In this paper, experimental evaluations for the powder coating system with chromium-free chemical conversion are discussed.

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The purpose of this study is to grasp anisotropy of bricks and to establish an appropriate compressive test method in evaluation of historic brick structures. From the previous experiment, it is clarified that extrusion-molded bricks have some anisotropy of compressive strength, and the compressive test method of JIS R 1250 is not appropriate, while JIS A 5210 is fine. In addition, arising mechanism of the anisotropy is discussed with a simple model of internal pore shape, and it is concluded that the anisotropy of compressive strength is caused by anisotropy of the pore shape which is generated in extrusion molding process.

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We present numerical results for hydrodynamic vibrations of two circular cylinders in tandem arrangement, which are mounted in a uniform flow. Two circular cylinders are assumed as each rigid body, and the circular cylinders are supported by damper-spring systems in in-line and cross-flow directions. In our computations, the gap ratio between the centers of two circular cylinders is set as 3 which is smaller than the critical gap ratio of two stationary circular cylinders. In addition, the Scruton number is given by 0.99. Vibration amplitudes in the in-line and cross-flow directions of the circular cylinders are computed by a third-order upwind finite element scheme and the numerical results are discussed in detail.

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A new vibration control system is proposed for residential houses. This system is a three-unit viscoelastic damper system which consists of two (upper and lower) rigid units and a damper unit including various rubber dampers supported by braces. The control system can absorb sufficient energy through the rubber damper. The ratio of the actual damper deformation to the interstory drift of the frame is introduced as a criterion to measure the damping performance and effectiveness of this system and it is shown that the proposed vibration control system has a high level of damping performance and effectiveness. A simplified earthquake response evaluation method is also proposed for the frame including the proposed control system. To verify the validity of the proposed vibration control system, a free-vibration experiment is conducted and some examples using the proposed simplified response evaluation method are presented.

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In developing countries of seismic area, many people have to live in traditional masonry houses. Though collapse of the houses is one of the most tragic losses of human lives, shift of the houses to construction based on modern engineering is difficult by socioeconomic reason. The authors have been developing a rocking pillar base isolation system suitable for masonry houses. Seismic performance of the system was discussed by vibration test of reduced scale specimen and numerical analysis in the previous paper. In this paper, we considered effect of mass eccentricity of the system with full-scale model analysis and applicability of response prediction using energy balance. Finally, we propose a basic design method for rocking pillar isolation system.

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We conducted a series of long period ground motion simulation of the Tokai-Tonankai-Nankai coupled earthquake considering 3D subsurface ground model including Kanto, Nobi and Osaka plain. We studied the influence of the location of rupture starting point and the contribution of each earthquake to the estimation results of the coupled earthquake. The results showed that the peaks of calculated pseudo velocity response spectra surpassed the uniform design spectra regulated by Building Standard Law. The simulated ground motions of Nankai and Tonankai earthquakes were dominant in Osaka plain. Those of Tonankai earthquake were dominant in Nobi plain and those of Tokai earthquake were dominant in Kanto plain. The duration time of the simulated ground motion of Tokai-Tonankai-Nankai coupled earthquake became longer than that of each earthquake. Furthermore, it was found that the Nankai earthquake amplified the long period ground motions exceeding 10 seconds in the Nobi and Kanto plains when the rupture started from the south east point of the fault plain.

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This study investigates the relationship between the strong motion records of super high-rise RC residential buildings and the indoor damages during the 2011 off the Pacific coast of Tohoku earthquake based on a questionnaire survey. The indoor damages, including the anxiety, the action difficulty and the overturning ratio of furniture were discussed in comparison with previous studies. The following conclusions were reached; 1) Levels of the anxiety and the action difficulty were greater than results in Takahashi et al. (2010) based on shaking table tests. 2) The overturning ratios of furniture were fairly consistent with Kaneko et al. (2002). 3) At the acceleration and the velocity which the overturning ratio of furniture starts to increase, most of residents felt difficulty in moving.

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This is a study of calculation formulas of first natural frequency of rectangular flat slabs of arbitrary width with various edge conditions. Formerly, only the calculations formulas on both the first natural frequencies the rectangular flat slabs with simple supported edges and all edges built-in have been proposed as the edge conditions. The arbitrary edge conditions except both of them have not been proposed so far. So an author derived the generalized calculation formulas of the first natural frequencies from the various edge conditions. The first natural frequencies of the ordinary flat slabs are intermediate between the simple supported edges and all edges built-in. So the author has defined the restraint along edges of the rectangular flat slabs as the former is assigned 1 and the latter is assigned 2. From the above-mentioned, the author has estimated that the first natural frequencies of the ordinary flat slabs would be one and a half times of the simple supported edges.

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In order to examine the factors affecting the three-dimensional dynamic behavior of pile foundation while soil shows strong nonlinearity, numerical simulations of several soil-pile-structure models subjected to strong shaking were performed. The tests were conducted using the large-scale shaking table at the E-Defense to investigate the response and failure of a nearly full-scale pile-structure system under multi-dimensional loading. It is shown that the numerical analysis can reproduce the behavior of the piles and superstructure as well as those of soil with a reasonable degree of accuracy, suggesting its applicability to soil-pile-structure system subjected to strong 3-D shaking.

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Dynamic centrifuge model tests are conducted to investigate the seismic behavior of a pile-supported building with embedded footing on semi-rigidly connected pile heads in liquefiable soil. The external force which acts on the piles with semi-rigid pile head connections during liquefaction is smaller than that with rigid pile head connections, because the superstructure acceleration and the seismic earth pressure acting on the embedded footing decrease due to the superior deformation performance of the soil-pile-footing system with semi-rigid pile head connections. Therefore, the effectiveness of semi-rigid pile head connections for reducing the pile damage could be enhanced in liquefiable soil.

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Dynamic tests and direct transient response analyses of finite element method were carried out to demonstrate the vertical dynamic response of light frame joist floor subjected to various impact forces (impact-hammer, heel-drop, clay-drop). The specimen was 3.64m-long-span and 3.64m-wide joist floor consisted of eleven 2" by 8" lumbers and 15 mm-thick T&G plywood subfloor.
The test results indicate, i) Dynamic maximum displacement of mid-span of the joist placed in the center of the floor obtained by the finite element method agree with those by experiments, ii) Dynamic maximum displacements closely relate to both the natural frequency of the joist floor and the processing time of impact force. iii) The static calculation using the coefficient (1.4) derived from the direct transient response analyses predicts the dynamic maximum displacements of the joist accepted the impact force.

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In the strengthening method for R/C buildings proposed by authors, steel frame is connected to the existing R/C frame through indirect joint. Experimental study was conducted, and the observed results suggested that that the steel frame restrains the increase of crack width of R/C column caused by reversal loading, and the strengthening effect can be performed without anchors in indirect joint of column. In order to support this finding theoretically, 3D FEM analysis is applied for shear failure R/C specimen. In this paper, it is discussed about the results of analysis and evaluation of stress transfer mechanism of indirect joint.

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Previous research shows the prediction of the shear capacity of column, with low web reinforcement ratios, based on truss and arch mechanism provided by AIJ gives underestimate strengths when consider axial load. In this study, experimental tests were conducted to evaluate the effect of axial force on ultimate shear strength calculated based on arch and truss mechanisms concept having specimens with low web reinforcement. From the experimental tests, the following conclusions were obtained: 1) the angle and width of compressive strut decrease and increase with an increase of axial load, respectively; 2) the estimation of column shear capacity including an increase of axial force was determined by modifying the shape of compressive strut; 3) the recent formula shows a good agreement with previous research results by using proposed factor of effectiveness concrete compressive strength; 4) the shear strength contributed from truss mechanism was not influenced by an increasing of axial load.

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This paper investigated the behavior of R/C beam-column joints in the plastic state subjected to repeated seismic load by static loading tests. The specimens were modeled on two types of structures constructed in recent years and 20 years ago.; i.e., tube structures , and moment-resisting-frame structures. The test results showed that at the story-drifts larger than yield deformation, (a) the stiffness deteriorated due to cyclic loads and the hysteresis loop changed to reversed-S shape, associated with concrete damage and the bond deterioration of the rebars in the beam-column joint, and (b) the ratio of energy dissipation by the beams decreased with increasing that of the beam-column joint.
In order to simulate these observed relations, a new hysteresis model for R/C beams was proposed. This model can reflect performance deterioration by reduction of the peak responses and several stiffness-related parameters. In this paper, the authors discussed those parameters of the model based on the results, however, the authors are still making efforts to verify the parameters with previous studies for the future.

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The post-buckling behavior of the seismic-resistant braces in braced frames under cyclic axial force is often evaluated by time-history analyses; however, they seldom consider brace fracture. Authors have proposed an easy evaluation method predicting the fracture point of the circular and H-section braces after buckling, using macro-models. However, the method is confirmed only against the test results of gradually increased amplitudes and applicability under other loading histories is not verified yet. In this paper, cyclic loading tests on the circular and H-section braces under various loading histories are carried out, and FEM analyses following the test results are performed. Reflecting these results, the validities of the proposed methods for the brace fracture prediction under various loading histories are discussed.

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This paper studies the stress-strain models to simulate the strength deterioration of the confined concrete and various sectional steel tubes in hollow steel tubular (HST) columns and concrete filled steel tubular (CFT) columns. The stress-strain models for above components by considering strength deterioration are simplified as to analyze steel and CFT frames subjected to ground motions. The model consists of an elastic-plastic curve up to the peak and a bi-linear after the peak which expresses the strength deterioration by negative slopes. The characteristic parameters of the stress-strain models for in-filled concrete and steel tubes are calibrated by comparing the component test results and the corresponding analytical results, and the proposed formulae for the deteriorating models of HST and CFT columns can accurately simulate the strength, stiffness and deterioration after local-failures.

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The authors have planned to develop hybrid structure formed by reinforced concrete columns and glued laminated timber beams. To connect concrete the columns and timber beams, the shear force should be transferred at the joints directly by certain mechanism.
The authors have planned to transfer the shear force using shear key formed by concrete and timber as a direct shear transfer mechanism. To verify whether the mechanism would be effective or not, the authors performed direct shear experiments. The specimens were made using normal strength concrete and Japanese cypress laminated timber, which had no reinforcing bars in the concrete of the shear keys.
The ratio of the length (h) to the thickness (t) of the shear key was selected as a parameter of the specimens, being varied from 3 to 7. The experimental results are reported in this paper, from those results the authors derived the following conclusions;
1. The shear force could be transferred by the expected shear transfer mechanism using the shear key formed by the concrete and the timber.
2. Different failure modes were observed in the specimens by varying the ratio of h/t. When the ratio of h/t was 4 or lower, the shear key failed in shear at the bottom, while the shear key failed in compression at the side area in case of the ratio being 5, though the concrete part of the shear key did not fail when the ratio was 6 or higher.

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The risk of pounding against the surrounding structures, usually against the retaining walls, has become a major concern about the seismic performance of base-isolated buildings subjected to unexpectedly large earthquakes. The required retaining wall clearance to ensure the superstructure of a base-isolated building not to yield is evaluated through incremental dynamic analysis and the required clearance-to-seismic intensity relationship is established. From this relationship, two characteristic clearances, namely the minimum required clearance, δ₁, and the maximum clearance, δ₂, may be identified. Given a base-isolated building and a seismic intensity, e.g., the energy-equivalent velocity in this paper, a retaining wall clearance greater than δ₁ would ensure a 50% possibility that the superstructure would not yield. On the other hand, the retaining wall clearance would impose no influence on the performance of the isolated building if the clearance is greater than δ₂. Especially, the minimum required clearance, δ₁, is of essential importance for the performance design of base-isolated buildings. A simple equation of estimating δ₁ for buildings with various parameters is proposed through data regression. In addition, a procedure of determining the required strength for the superstructure, given a seismic intensity, is also proposed.

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