In this paper, air entraining properties of fly ash concrete was investigated experimentally, and an estimation method of the dosage of air entraining agent for fly ash concrete was proposed. The results shows that the required dosage of air entraining agent in fly ash concrete was much higher than that in ordinary concrete. In the estimation method, fly ash content is changed to cement content equivalent value using basic properties of fly ash, and dosage of air entraining agent is calculated. And it appears that the method is useful when using absorption weight of methylene blue as the basic property.

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Deterioration of stones such as delamination, discoloration and efflorescence, which became evident during on-site surveys was investigated from petrological and chemical viewpoints. Results showed that most cases of the deterioration were caused by chemical reactions of inherent minerals to external water absorbed or action of crystallisation force caused by soluble salts in water to the fragile texture. To summarize, the deterioration can be classified into the following categories: 1. Exfoliation by expansion due to oxidation of iron sulfide minerals 2. Delamination of weak cohesive structure due to florescence 3. Exfoliation by saturation and dissolving of zeolite minerals 4. Discoloration by rust of iron sulfide minerals 5. Dissolution of carbonate materials due to acid rainwater 6. Efflorescence from crack and weak cohesive structure by soluble salts Much of the deterioration due to minerals inherent in stones was clarified. Many imported stones without adequate data are being used in construction. Therefore, the importance of obtaining data on these materials, especially petrographic data, can be emphasized.

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The constants of specific water capacity α, moisture permeability λ and surface factor f are included in a partial differential equation, representing the moisture movement in cement-based materials and its boundary condition. Therefore, they must be made clear to analyze the moisture movement. In this paper, the following two series of experiments were made to obtain them for carbon fiber reinforced mortar. (Series 1-the measurement of α) Written in a differential form as α = dWe /dh (We : evaporable water, h : relative humidity), a was obtained from measuring h-We relationship. (Series 2-the evaluations of λ and f) The evaluations of λ and f were made by means of the inverse operation, fitting the measured values of t-Wd relationship with the calculated ones.

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In order to quantitatively evaluate corrosion state, rate and environment of reinforcing steel in concrete structures, an embeddable minisensor has been newly developed. This sensor has both a counter electrode and a pseudo-reference electrode made of gold. Minisensors can be embedded adjacent to reinforcing steel in order to minimize the concrete cover effects on the three kinds of electrochemical characteristics to be measured. Using minisensors, continuous monitoring is possible to catch the sensitive corrosion behavior. This paper describes the results of investigation on the influence of pH, contamination with both chloride ion and calcium nitrite of immersed cementitious solution on both the natural potential and polarization resistance readings using minisensors in comparison with the ordinary electrode method having both a Ag/AgCl reference electrode and a platinum counter electrode. As a result, it was clarified that the minisensor has a satisfactory performance for measuring the electrochemical characteristics of reinforcing steel in concrete.

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To clarify the cause of the structural damage due to earthquake, it is necessary to estimate quantitatively the input earthquake motion which caused the damage to structures. This paper presents a probabilistic method to assess roughly the input earthquake motion to structures in the case that only the damage state of structures is known and the input earthquake motion to it is unknown, analyzing statistically the sample data concerning the input earthquake motion obtained from the observation system and each damage state of structures. In this paper, an analytical approach using fuzzy theory as a mean to define each damage state of structures is formulated and discussed. It is hoped that such a tentative study will help to explain the damage factor which caused the damage to structures.

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This paper discusses following subjects related to elasto-plastic behaviors of tall buildings for across wind action by numerical response analysis with multi-mass models with equivalent shearing stiffness. Firstly, to clarify the applicablity of the suggested response analysis method with one-mass model, effects of higher mode vibrations and changes of mode shapes with the progress of structural yielding are examined. Secondly, the applicability of the mode correction factor which is often used in a case of elastic response analysis is examined. And lastly, energy distribution properties for elastic and elasto-plastic vibrations are discussed, and a simple estimation method is presented. Obtained major findings are as follows; 1. Effects of higher mode vibrations and changes of the first mode shapes are very small. 2. The mode correction factor about the first generalized wind force, which has been used is elastic response analysis, is applicable for elasto-plastic response analysis. 3. Distributions of total input energy are approximately similar to them in elastic responses except for peculiar cases of distribution of the elastic limit of inter story deflection in bending type buildings.

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In this study, we investigated the effect that the quality of accumulated snow on the snow's resistance to sliding. First, we observed changes in the quality of snow that had accumulated on the roof of a building. It was found that the particle size of the snow increased to approximately 2mm after one week and that the water content of the snow increased. Next, experiments were conducted to determine the effect that particle size of snow on a sloped roof has on the snow's resistance to sliding. The results showed that the resistance to sliding decreased as the particle size of snow increased (i.e., as the snow became more granular). The effect of particle size on the snow's resistance also depended on the degree of snow melting. From the facts described above, it is possible to utilize the effect of particle size on the snow's resistance for control of snow sliding on a sloped roof.

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In order to understand physical mechanism of the vortex-induced vibration, the Vortex-in-Cell method, which incorporates viscous diffusion, is applied to unsteady flow and vortex motions around an oscillating circular cylinder. Firstly, we investigate the computational results of flows around a stationary circular cylinder in the range of the low Reynolds numbers and the accuracy of the present method are shown. Secondly various patterns of vortex formation around a forced oscillating circular cylinder are examined as a function of amplitudes and frequencies. Through the comparison with the previous experimental data, details of various modes of vortex motion are classified.

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The artificial neural network is a newly developed technique for the identification and modeling of linear and nonlinear dynamic systems through the use of measured experimental data. In this paper, a neural network approach is employed for predicting the hysteretic restoring forces of structures and applied to dynamic response prediction for a single and multi degree of freedom system with restoring force characteristics of Ramberg-Osgood type. A multi-layered backpropagation neural network is chosen as the neural network to determine the restoring force at the next loading step as an output with the displacement responses and the corresponding restoring forces at the past few loading steps as inputs to the neural network. The application examples show the great promise of using the neural network in modeling of the nonlinear hysteretic behavior of structures.

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The soil around a pile subjected to earthquake excitation often becomes nonlinear. The dynamic characteristics of nonlinear soil-pile system are shown from the result of the forced vibration test in this paper. The single pile and 4-piles that are concrete piles are vibrated using the exciter in the test. The vibration loads of the piles are increased in three stages. It is found from the result of the test that the material nonlinearity is more effective than the geometrical nonlinearity for the behavior of single pile and the geometrical nonlinerity is more effective for the behavior of 4-pile. The results of test are simulated using the thin layer formulation that is modified for nonlinear analysis. The result of analysis agrees with the result of test after passing through the maximum displacement at the pile head.

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The present report concerns a friction damper constructed with coned disc springs as a part of laminated rubber bearings for base-isolation systems. This friction damper is constructed by keeping coned disc springs against a horizontally placed stainless steel plate on the sliding surface by making use of the rebound from deformation by vertical compression. The examination of non-linear load-deflection curves of the coned disc springs were undertaken by both characteristics tests and analysis. Through dynamic characteristics tests, the reliability of friction dampers constructed with the coned disc spring was confirmed as applicable to a base isolation system.

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The ductility and energy dissipation capacity of a seismic resistant frame structure depends upon the collapse mechanism very much. Hence the philosophy of strong-column-and-weak-beam is generally recommended for the seismic design, and many studies on this philosophy were presented. However, it is not yet easy to find the frame structure, which certainly achieves the desirable collapse mechanism. In this paper, a reliability-based minimum weight structural design method is presented which is able to control the probability of the specified collapse mechanism indirectly. In this study, the yield strengths of members are selected as random variables, and Monte Carlo simulations check the probability of the specified collapse mechanism of the frames designed by this method.

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The following two analytical problems for supporting the construction planning of structures by using computers are studied: (1) Analysis of initial shape before construction An analysis of initial shape before construction with estimating construction process is proposed in this paper. An example of truss structures is analyzed. (2) Inverse analysis for construction process by removing members An inverse analysis for construction process by removing members is proposed in order to find an optimum solution of the construction process satisfying given criteria. The analysis searches for a construction process satisfying given criteria by removing members in order from a finished structure. Examples of truss structures are analyzed.

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In this paper, a method of optimizing the shape and the stiffness distribution of a thin-walled beam structure is presented. The thin-walled beam can be analyzed by a finite element method based on the beam theory considering shear warping deformation. The objective for the optimization of shape and stiffness distribution is to minimize the compliance of the structure under the condition of a volume constraint. The size ratio of each cross-section and thickness of membrane plates are selected as the design variables. The optimum design problem is solved by sequential linear programming method. By a fundamental example of 2D cantilever beam, the validity of present method is shown. For the application of present method, highrise building models are analyzed as a thin-walled beam with equivalent strain energy. And the applicability of present method for the structural design or design planning of highrise building is investigated.

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Unified and effective hybrid stress finite element approach for dynamic deformation problems of frame structures have been formulated, and its excellent promosing potentialities for the dynamic problems as well as the static have been verified with several numerical tests in Refs. 3)-5). In this paper, new another hybrid stress finite element method/procedure with aid of the iteration method, especially for free vibration problem of frame structures, is presented. Based on the variational consideration developed in the previous reports, appropriate iterative approximation are interpolated in the relations of resultant stress and displacement parameters, and which might lead to drastic reduction of the degree of freedom. Mechanical meanings of the present iterative approximation and its relevance to the ordinary assumed displacement finite elements are discussed and clarified. Also, two specific iterative calculation procedure, which are effective to accelerate the progress of convergent process and to save the computing-time, are shown. Several numerical tests are performed, and show that the present method/procedure yield no descretizing errors, in practice, and so, have excellent capacity to simulate accurately and facilely free vibration behavior of the more complicated space frame structures.

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An efficient computational method has been developed by the authors for predicting the large deflection behavior of spatial rigid frames. The method is based on the beam-column finite element method with the incremental perturbation technique. The three-dimensional finite rotations are exactly incorporated in the method. This paper shows that the author's method accurately predicts the experimental results on the large deflection behavior of model rigid frames. The model frames are made of styrene and acrylic plates which keep elastic up to large deflection range. It is also shown that the finite element model with warping function is able to predict accurately the theoretical lateral buckling load of a simply supported H beam.

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A rational pile design balanced with the ultimate design method employed for superstructures requires the ultimate capacity of piles especially the shear strength. In the current design of the pretentioned spun high strength concrete pile (hereafter referred as PHC pile) prescribed by JIS, only an allowable stress design is assigned, then the safety against the ultimate failure has not been examined. In this research we carried out the anti-symmetric bending shear tests on the full scale to 1/4 models of the large diameter PHC piles. According the test results, we evaluate parameters affecting on the ultimate shear strength of the pile, and also examine the conformity of the previously proposed theories for the ultimate shear strength.

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In this study, the micro-tremor measurements were conducted both for a wooden framed house and ground surface beside it in Kobe City. A part of the house under investigation was damaged seriously compared with the other part. In order to explain this local damage, the authors studied the vibration characteristics of the timber house in detail. Furthermore, the behavior of the house was analysed by assuming the discrete mass system taking the elasto-plastic characteristics of the walls into consideration and estimating the earthquake motion to identify the cause of the damage. The elasto-plastic constitutive equation of the wall was assumed to be degrading tri-linear reduced from the behaviors of two major components of the house. Analytical response was obtained using the observed earthquake motion as input. As a result, the cause of the local damage of the house was proved to be the torsional vibration due to insufficient amount of bearing wall on the west side of the first floor.

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Spline joint has been usually fixed with nailing on the frame of structure. So it is impossible to release from the diformation of the structural frame. In this report, wall panel with a spline joint mechanism has become to have a curtain wall mechanism with introducing peculiar hardware. Especially that has discussed from the structural and the extent of accomplishment point of view.

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Deflection of reinforced concrete slabs increase with time due to factors like creep of concrete, the decrease in the rigidity by cracking. Moreover, additional deflection after cracking is known to occur becouse of steel slippage at the fixed adge. In this paper, a method that can calculate long-term deflections of continuous reinforced concrete slabs is given. Steel slippage is evaluated by bond creep analysis in this method. A comparison of the experimental and calculated deflections shows that both are generally in agreement. The effects of slab thickness, slab effective depth, ratio of reinforcement and orther factors on the deflection of slabs are numerically analyzed.

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This paper studies the relation between structural damage of reinforced concrete buildings and ground motion intensity during the 1995 Hyogoken-Nanbu earthquake. We have used two surveyed data for damaged schools and mid-to-high-rise buildings which list description of buildings, structural damage degree, and seismic performance indices. Buildings are classified and their damage are regressed by construction years, seismic performance indices, number of floors, and peak ground velocities based on tree based model. Obtained regression and classification trees show how the effects of ground motion intensity on building damage vary with the seismic performance of the building, damage degree, and peak ground velocities.

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