This paper reports on the influence of coarse aggregate on the fracture properties of concrete subjected to high temperatures up to 800℃. The fracture properties were evaluated based on tension-softening curves which were determined by polylinear approximation through inverse analysis of load versus crack mouth opening displacement (CMOD) curves, obtained from wedge-splitting tests using a dedicated analysis program. The follow conclusions were found in this study: The initial cohesive stress of mortar was higher than that of concrete. And the fracture energy of concrete was higher than that of mortar.

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A slump test and a cylinder penetration test were conducted for 155 kinds of concrete with different grading of fine aggregate and different mix proportion, and a flow test was conducted simultaneously for wet-screened mortar. Additionally, the consideration based on the excess paste theory was conducted. The following findings were obtained as the results. (1) The segregation degree of concrete is evaluated quantitatively by an inflow mortar value, the result of the cylinder penetration test, and the inflow mortar value corresponding to the limit of segregation is 30 mm. (2) The fluidity of matrix mortar has a dominant influence on the segregation degree of concrete. Furthermore, the new procedure of mix design which can reasonably consider the segregation resistance of concrete was proposed based on these findings.

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As one of the utilization of the fly ash, a method to mix fly ash as some fine aggregate at the time when it produces concrete is cited in crushed sand to supplement for fine grain. In this study, fresh property of concrete using fine aggregate which pre-mixed fly ash in concrete production and strength properties were examined. In conclusion, workability and materials separation resistance of concrete were improved by using FAS in comparison with only using crushed sand. About compressive strength, concrete using pre-mixed sand was concrete using crushed sand and river sand and higher than same class.

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Surface layer of concrete becomes the most heavily damaged part affected by high temperature heating when concrete structure is subjected to fire accident. In the surface layer of concrete structures, the anchor bolts are used for fixing the equipment or the seismic strengthening elements. This paper reports on the investigation into the influence of high temperature heating up to 1000℃ on pull-out properties of two types of mechanical anchor embedded in concrete. Relationship between the pull-out strength of anchors and the fracture energy was also investigated.

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The aim of the present paper is to introduce a practical method to estimate the special distributions of ground motion, based on Kriging analyses using ordinary boring investigation data and one-dimensional earthquake response analyses. By this method, strong ground motions can be estimated accurately at a minimum costs. Because the Kriging analyses can also provide quantitatively the estimation errors, the low accurate estimation areas can be found at a glance in the all area. The sample analyses suggest us to utilize various countermeasures, which should be adopted due to the necessary, purposes, cost-performances, etc. The various best decision-makings can be performed toward the best countermeasures for earthquake disasters mitigation based on the introduced practical method.

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We proposed a new procedure for evaluating the parameters of the asperity models for predicting strong ground motions from inland earthquakes caused by long reverse faults. The evaluation formula of averaged dynamic stress drops obtained by Irie et al. (2013)¹⁾ for surface ruptured faults 15 to 300 km long was adopted in our procedure, because the evaluation formula of the averaged static stress drops for circular cracks, commonly adopted in existing procedures, could not be applied to surface ruptured faults or long faults. The averaged dynamic stress drop was estimated to be 24 bars from the data of the ruptured areas and the seismic moments of actual earthquakes, and the dynamic stress drop on the asperities was estimated to be 187 bars from the data of the short-period levels and the seismic moments of actual earthquakes. These results led that the asperity areas were 11 % of the entire ruptured areas.

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This paper proposes a performance based design diagram to estimate cumulative responses of bilinear hysteretic systems using triple elastic response spectra. The design diagram is based on a concept of separated variables of an energy spectrum for the target seismic ground motion; that is, energy spectrum S_eq(T) can be expressed by the product of an elastic spectrum S(T) and empirical formulas including the parameters of viscous damping ratio h, ductility factor μ_d and bilinear stiffness factor p_d,. This paper proposes modified energy spectrum V_E,40/ newly defined, in addition of pseudo velocity spectrum _pS_v,40 and velocity spectrum S_v,40 utilized in the previous diagrams. The paper shows that the cumulative responses estimated by the proposed diagram are accurately agreed to the results computed by non-linear time history analyses of 239,400 cases.

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The mechanism of earthquake energy input to connected building models on flexible soil is clarified. The earthquake input energies to super-structures, connecting dampers, soil-foundation systems and total system are obtained by taking the corresponding appropriate free bodies into account and defining the energy transfer functions. It has been made clear that, when the soil becomes softer, the effectiveness of connection dampers decreases. This phenomenon can be confirmed by the change of properties of energy transfer functions. It has further been disclosed that the maximization of the area (input energy to connecting dampers) of the energy transfer function for connecting dampers is a good index for determination of connecting damper quantity.

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It is pointed out that the input acceleration to a building may be small compared with the acceleration of ground surface in the recent great earthquakes. In this paper, dynamic centrifuge tests using a rigid structure supported by saturated sand deposit were performed to investigate the influence of groundwater level. It was shown that the foundation was adsorbed to the ground by negative excess pore water pressure in case of groundwater level equal to the foundation base. Therefore, there is a possibility that the groundwater level has affected the structure damage during severe earthquakes.

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Simplified formula to predict the performance of sheathed shear elements reinforced with shear keys along panel joints is derived in this paper. The formula is verified by numerical static elasto-plastic analyses for various values of the ratio C of the stiffness of nails to that of shear keys. Results predicted by the formula that consider the behavior of all panels well agree with those by numerical analyses. The formula becomes complicated as the number of panels increases. When the formula is simplified, the validity of the formula depends on the number of panels and the value of C.

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Authors have already proposed the limit-analysis model which analyzes the maximum strength of reinforced concrete shear wall. This study describes the simplified model based on this model. The simplified model is accomplished by restricting failure mechanisms. Both models considered with bending and shear strength of columns and beams around a wall. The analysis result of the model is almost the same as the original limit-analysis model. The model reflecting shear strength of columns and beams is more appropriate than the one only reflecting bending strength of columns and beams.

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Full-scale in-situ testing of a building frame that was seismically strengthened with a K-type steel brace was carried out. The experimental results showed the tensile and compressive yield for the brace, and shear failure of the RC columns. The strength obtained satisfied the assumed design values. Strength and ductile resistance types applied. The shear strength and bending strength of the existing RC columns were greater than the analysis values, because the upright frame member of the brace frame extended to the rigid section of the existing RC columns and beams, and combined with the existing RC columns.

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This paper discusses the influence of floor slabs on deformation capacity of welded beam-to-column connections used for steel moment resisting frames until ductile fracture due to cyclic loading. Two types of specimens with different flexural strength of beam end connection were prepared. The tests were carried out under cyclic loading with specified beam rotation amplitudes. In order to investigate the influence of floor slabs on strain behaviors of lower beam flanges, analysis on basis of column deflection curve is carried out. The relationship between plastic strain amplitude ε_p of beam flanges obtained by the analysis and cumulative plastic deformation η obtained from the tests is revealed.

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Shear panel dampers consisting of stiffeners and a panel surrounding four flanges are used as aseismic dampers for buildings in Japan. Cracks can easily form in the shear panel damper when the panel undergoes shear buckling during cyclic loading caused by a severe earthquake. For relatively thin panel, when width-to-thickness ratio is large, the plastic deformation capacity of the damper can be evaluated by using the maximum-deformation-angle. Then the shear buckling in elasto-plastic range can be detected by checking maximum-deformation-angle. An expression for estimating plastic deformation capacity for shear-thin-panel-damper, which has parameters such as normalized width-to-thickness-ratio and deformation angle, is presented. To show the validity of the expression, cyclic loading tests of shear-panel-damper were reviewed and performed . Also clumped panels subjected to cycle in-plane shear deformation were analyzed using geometrical and material non-linear F.E.M. analysis to check the expression. These results showed the validity and effectiveness of the expression for shear panel damper.

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A shear panel dampers, consisting of stiffeners and a panel surrounding four flanges are used as aseismic hysteretic damper for buildings in Japan. Cracks can easily form in a shear panel damper when the panel undergoes shear buckling during cyclic loading caused by a severe earthquake. Shear buckling can be detected by checking the maximum deformation angle. For relatively thick panel, when width-to-thickness ratio is large, the damper's plastic deformation capacity can be evaluated from the maximum deformation angle. However, when width-to-thickness ratio is relatively small, very-low-cycle fatigue life is essential for relatively thick panel to predict the damper's usage limit because failure pattern changes where cracks forms the welding between panel and flanges. Fatigue life relation for shear thick panel damper, which has parameters such as normalized width-to-thickness ratio and deformation-angle is presented. Also the method for predicting fatigue life under a severe earthquake is presented. To show the validity of the prediction expression, cyclic loading tests of shear panel damper were reviewed and performed to verify the expression. The applicability of the method for predicting fatigue life of the damper is confirmed through non-stationary cyclic loading tests. These results showed the validity and effectiveness of the expressions and the method

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A large numbers of steel roof bearings in RC gymnasia are damaged at 2011 Tohoku Earthquake, and out-of-plane response of cantilevered RC walls supporting the roof frame is identified as one of main causes of damage. In order to use these gymnasia as shelters after the earthquake, they are required seismic retrofit. However, a conventional seismic retrofit method requires strengthening bearings with steel corner plates and replacing all the roof braces, which is uneconomical. In this paper, a seismic retrofit method inserting energy-dissipation elements into roof bearings is discussed and their response reduction effects on the gymnasium are investigated. Furthermore, a simplified response evaluation method using equivalent SDOF system and equivalent linearization technique are proposed to determine the optimum design of the energy-dissipation bearings.

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In recent years, the collapse of ceilings due to earthquakes has become a serious problem. The authors have proposed the reinforcing method to improve the aseismic performance of conventional ceilings. The proposed method employs the partial reinforcement only around the braces of ceilings, and can be easily and economically applied. The shaking table tests of the partially reinforced ceilings were carried out to investigate dynamic characteristics. The analytical model of the reinforced ceilings is proposed based on the static cyclic loading tests and the simulation analyses were carried out to show the effectiveness of the analytical model.

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There are some types of damper to reduce the building vibration such as earthquakes. It is important for every damper to evaluate the stiffness of its component for the accurate formula of damper characteristics. This paper's Part1 showed the relationship among damping component, integrating components and supporting members in the viscous-type damper of the brace type, and 2 kinds of the damper characteristic formulas that were detailed and approximate. It proved that the approximate formula was accurate like the detailed one and it could be used in time response analyses. This paper shows characteristics in the viscous-type damper of the wall type with the method same as Part1's. The formula of the wall type damper is more complex than that of the brace type, because shearing and bending forces are generated at the same time and the latter force depends on the aspect ratio of the damper shape.

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The aim of this study is to evaluate indoor damage in high-rise residential buildings due to long period ground motion. In this study the seismic behavior of a refrigerator was evaluated considering opening doors and drawers using shaking table tests and simulations. As the result of this study, the doors and drawers begins to open about 150 cm/s² in case that contents exist, and the refrigerator begins to move about 250 cm/s². And the refrigerator collides many times against walls severely with scattering contents during floor shaking. So it is highly possible that it blocks evacuation routes and injures people

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