The compressive strength and internal organization of the heat curing test piece and 20℃ seal curing test piece that made with the high strength mortar using the low heat portland cement and silica fume were confirmed. As a result, the compressive strength of the heat curing test piece at three days is almost equal to that of the 20℃ seal curing at 91 days. As a result of an internal analysis, the pore size distribution curve and the amount of the calcium hydroxide of the heat curing test piece at three days was almost equal to that of 20℃ seal curing at 91 days.

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In this paper, the prediction formula of total creep strain of concrete with a normal to high strength concrete was discussed using the test data published in Japan. The proposed model was expressed as the product of two terms; one is the creep parameter that is expressed in terms of the product of four coefficients taking into account of mix proportions, age at loading, relative humidity and the effect of specimen size, the other the time-effect function with no finite limit (logarithmic function). It was found that the proposed prediction formula can estimate the total creep strain more accurately than the other formulas such as JSCE, CEB-FIP 1990 and ACI209.

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In order to clarify characteristics of separated shear layers above a roof of a cubic model and wind pressures on the roof, a wind tunnel experiment was carried out. The flow was measured by Particle Image Velocimetry (PIV) system and simultaneous multi-pressure measurements on the roof surface were also performed. In this paper, relations between instantaneous separated shear layers above the roof and instantaneous wind pressure distributions were presented. Characteristics of instantaneous wind pressure distributions at the instantaneous reattachment were also discussed.

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A new strategy for structural control systems using passive devices is proposed. The proposed strategy does not rely on the uniform distribution of dampers. It has many merits over the conventional methods. First, some floors do not have any dampers so that flexible use the floor space is possible. Second, concentrated distribution of dampers will lower the installation cost. Third, the structural reliability is improved as the number of floors with dampers is reduced. The effectiveness of the strategy is further enhanced if it is possible to soften the stiffness of the story where dampers are installed. By doing so, the amount of the energy absorbed by the dampers installed in the story is significantly increased.

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The sliding bearings are used for lightweight structures instead of the laminated rubber bearings. In many studies, the frictional coefficients of sliding bearings are assumed as less than 0.10. However, even if frictional coefficient is about 0.20, it may be effective for a big earthquake (Max. acceleration > 200Gal). In this study, the efficiencies of sliding bearings made of stainless steel are examined. The static and the dynamic frictional coefficients were identified about 0.20 and 0.10, respectively. It demonstrated experimentally and analytically that the inter-story displacements decreased to 25〜50%.

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The effectiveness of vibration control by connecting adjacent buildings with dampers and springs has been studied, and applied for retrofit of existing buildings and even for design of new buildings. However, the need of separate buildings limited the exploitation of the great potential and efficiency of this type of control strategy. One significant feature of the connected system is a new overall stiffness matrix that is utterly different with ordinary buildings or structures constructed by traditional methods. As a generic problem, strategies for optimal structural control may be further discussed based on model with possible arbitrary vibration characteristics. If this is advantageous, then the next step is to realize the scheme for the assumed vibration characteristics practically and economically. In this paper, two masses of a single building are connected by rocking and lever mechanism, and constructing a vibration system with variable stiffness matrix utterly deferent from traditional structure that have only a predominant first vibration mode. Based on the similarity in stiffness matrix, this new type of structure is optimal designed using formulas already developed for separate buildings linked together. It was found that the peak magnification factor could be greatly reduced for stable vibration, and a rapid damping of maximum response subjected to earthquake waves was also recognized. However, the reduction in earthquake response may not be significantly according to ground motions. As no special devises are needed for this new structure, it is expected that the arbitrary formulation of stiffness matrix be further investigated for both passive and active vibration controls.

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Pile foundations near the shoreline in Kobe city were severely damaged due to liquefaction-induced lateral spreading during the Hyogo-ken Nambu Earthquake, January 17,1995. Kuwabara and Yoneda (1998) presented an excelent case history of damage to a cast-in-place concrete pile foundation of a building that was under construction during the earthquake, but with little consideration of the effects of lateral speading on the damage. The objective of this study is to investigate the effects of lateral spreading on the damage based on effective stress response analysis of a soil-pile foundation system. The observed strong motion in a borehole array at Higashi-Kobe Bridge is employed as an input motion to the soil-pile foundation system. It is found that soil response near the shoreline are greatly affected by liquefaction-induced lateral spreading and that the damaged mechanism of pile foundations varies greatly with distance from the shoreline.

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The purpose of this paper is to propose modeling technique of shear-wave velocity structure of the surface layers for a seismic hazard map where the unit of estimation is detailed. In the Nagoya City region, 40420 standard penetration test data and 342 PS logging data have been accumulated and the geologic structure is presumed. Using these data, shear-wave velocity structure of the surface layers is modeled. This model expresses the distribution of a detailed N-value in a stratum, and reproduces a suitable soil dynamics, compared with H/V ratio of microtremors at 340 sites in Nagoya City and the geomorphological land classification.

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Viscoelastic damper dissipates energy through shear deformation of the viscoelastic material, and this causes temperature rise and softening of the material. Under long duration load, however, significant heat conduction and transfer can occur and control the temperature-rise effects. These and frequency sensitivities are included in the two analysis methods proposed: The first method combines three-dimensional heat transfer analysis and static analysis using a common finite element model of the damper, and estimates damper dynamic properties under long duration load. The second combines one-dimensional heat transfer analysis and viscoelastic constitutive rule using fractional time-derivatives of stress and strain, and it calculates step-by-step the force-deformation time histories of the damper. Good accuracies of both analysis methods are demonstrated by comparing with the results of experiments applying cyclic loading of long duration.

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In recent years, response control structures have been widely applied for the seismic performance based design of new buildings and retrofit of existing buildings to achieve high seismic performance. And the prediction method based on energy balance has been presented for them, however it is limited for the case the response of main structure remains in elastic range. In this paper, the prediction method based on energy balance is extended for the case of the main structures respond beyond elastic range. In this method, the maximum response is obtained from the energy balance at the time the maximum response occurs and the cumulative energy response is obtained from that of whole energy during earthquake. The validity of the proposed method is examined by nonlinear time-history analysis.

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This paper evaluates the effect of geometrical nonlinearity on the buckling load of laminated rubber bearings. In the past research, the author proposed a nonlinear buckling model for shear-bending columns, which revealed the fact that the reduction of lateral stiffness of rubber bearings in a large horizontal displacement depends on their configuration. It has been believed that the low-rise elastomeric columns have a more stable load-displacement characteristics than slender ones. The model, however, clarified the risk of the unstable post-buckling behavior latent in the flat configuration of bearings. On the other hand, the slenderness of elastomeric columns plays an important role to maintain their load supporting capacity in a large deformed area. These analytical discoveries are numerically investigated and compared with some experimental observations.

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In this paper, we propose that a optimum design system to aid structural design in practice should present sensitivity derivatives of an objective function with respect to the parameters of structural performances. It is shown that the sensitivity derivatives of the objective function are evaluated inexpensively by Lagrange multipliers which are by-products of the optimization scheme. And, we study the dual problem which has close relationship with the sensitivity analysis of the optimum design to present that the balance between the cost and the performance which structural designers are concerned about is represented by inequalites between the derivatives of the cost and the performances with respect to the design variables.

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For evaluating the earthquake-induced settlements of clay deposits, soil tests on remolded samples and undisturbed samples were carried out. From the results, the following conclusions were obtained. 1)The volumetric strain after cyclic shear loading depends on the maximum shear strain induced during the cyclic shear. 2)The undrained cyclic shear stress ratio R_<15> is expressed as proportional characteristics of an over-consolidation ratio. 3)A simplified method was presented for estimating the earthquake-induced settlements. Centrifuge model tests were performed and the settlements estimated by the proposed method showed good agreement with those measured in the tests. It is suggested therefore that the proposed method can be used as an estimation of earthquake-induced settlements of clay deposits.

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To establish the structural design method which can estimate a seismic performance accurately, shaking table tests were made for wood-framed residential structures using full-scale model. A total floor area of the model was 125.9m^2. The Ground acceleration with 1000gals seismic motion was applied. The motion was amplified from the JMA-kobe (NS) which was recorded in the 1995 Hyogoken-nanbu earthquake. The motion were applied three times. However, no critical damage was found. It was made clear that the model was strong enough. The maximum response acceleration was recorded as much as 2095gals on the 2nd floor and 3374gals on the roof in the excitation of 1000gals of JMA-kobe. It was found that the maximum storey shear was recorded by 322kN, that is equivalent to 1.8 in base shear coefficient. It was made clear that the model has high ductile performance. The maximum storey shear of the model was 3 times as much as estimated value. Also the proportion of the shear wall was equal to or less than 1/2 of the total storey shear, and the non-structural secondary walls contribute mainly to the seismic performance.

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In this paper, I discuss the influence of the bearing force distribution on aseismatic performance of traditional timber houses. In order to discuss the distribution of bearing force in each wall, Monte Carlo simulation is employed. 208 exist houses are analyzed, and 100 analysis models are made in each house. The assumption of rigid floor and non-structural wall resistance force are also concerned. The results may be summarized as follows: the horizontal resistant forces calculated by deterministic models are the lower limit of the horizontal resistant forces of data spread models. The ratio of the maximum displacement response by data spread models over ones by deterministic model changes according to the type of an earthquake motion and its peak ground velocity.

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The purpose of this paper is to compare the evaluations between seismic diagnoses, and to explain relationship between the evaluations and earthquake damage levels. First, 111 conventional wooden houses damaged by the Hyogoken-Nanbu Earthquake are diagnosed. Therefore, earthquake damage levels of these houses are judged. Major findings are as follows. Even with the same house, the evaluation may differ widely according to the seismic diagnosis. As the estimation of earthquake resisting elements become more delicate, the correlation of the evaluation with the earthquake damage level become higher, in other words, the reliability of the evaluation become higher. On the other hand, it is difficult to specify the damage level from the evaluation, because the standard deviation of the evaluation is not small.

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For concrete prefabricated houses of 2 stories investigated in this paper, which is a wall-type structural system consisting of precast reinforced concrete panels with ribs, an evaluation of the structural performance using the Calculation of Response and Limit Strength with nonlinear static analysis was fulfilled a duty with the revision of the Building Standard Law of Japan in 1998. This paper presents an evaluation procedure for the seismic performance of the houses based on structural testing on the members, assemblages and partial frames, which is conformable to the Calculation of Response and Limit Strength.

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In this paper, firstly it is noted that a limit strength of structural member in a seismic response is determined by both of the maximum deformation and the cumulative absorbed energy, based on the past study about the low-cycle fatigue and the cumulative damage estimation. Next, it is shown that a ratio of the maximum deformation and the cumulative absorbed energy in a seismic response is an approximate function of the duration time of the seismic motion, based on the theory of random vibration. As a result, relationship between two methods of seismic design formulated in Japan, namely 'Calculation on response and limited strength' and 'Energy-based method', is found out.

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