It is well known that the moisture curing is serious influence on the strength development of concrete. In this study, the influence of moisture curing on the strength development of concrete is analyzed quantitatively. In the experiment, the strength development, the free water content and the bonding water were examined on the 3 strength level concrete in various humidity conditions. The results of this study are as follows; The content of free water in concrete is low in case of low humidity. The quantity of bonding water is low in case,of low moisture content. The strength development of concrete becomes small when the relative humidity become low. The mathematical model for the rate of hydration is established. The compressive strength could be calculated by the mathematical model.

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In this paper, conditions of simple insulation curing of test specimens were studied, for purposes of strength control of concrete structures in cold weather. The temperature histories of the specimens in the simple insulation curing boxes corresponding to those of the concrete structures were researched by means of concrete experiments and temperature analysis by finite element method. Based on the result of the experiments and the analysis, the conditions of simple insulation curing of test specimens corresponding to the temperature history of concrete structures in cold weather were able to be given by empirical formulae. The accuracy of the formulae was proved by the experiment.

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The main purpose of this paper is to demonstrate the necessity of considering wind load combinations even for low-rise buildings. It first discusses the overall quasi-static wind load effects and their combinations to be considered in structural design of low-rise buildings. It was found that the maximum torsional moment closely correlates with the maximum along-wind base shear. It was also found that the instantaneous pressure distribution causing the maximum along-wind base shear was quite similar to that causing the maximum torsional moment, and that this asymmetric pressure pattern simultaneously accompanies considerable across-wind and torsional components. A comprehensive study of these phenomena was made by checking the phase-plane behaviors and cross-correlation of the absolute values of the load effects. The maximum normal stresses in column members were also examined to discuss the wind load combination of the along-wind, across-wind, uplift, and three moments.

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The LES in curvilinear coordinate system are applied to the flow around a square cylinder in uniform and homogeneous turbulent flows. We use the statistical method proposed by Hoshiya to generate inflow turbulence. Firstly, we confirm the accuracy of the present computational results about the flow around a square cylinder in uniform flow. Next, the applicabilites of the present numerical method to prediction of aerodynamic characteristics of a square cylinder as a function of intensity of homogeneous turbulent flow, are shown. As a result, we show the present method can simulate the effect of turbulence intensity on the flow around a square cylinder.

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We have in our preceding paper proposed the basic concept of Regional Vitality as an index for evaluation of earthquake risk potential and also the technical method of evaluation of Economic Vitality, presenting a case study on the evaluation of the damage done by the 1995 Hyogoken-Nambu Earthquake in the Hanshin region and vicinity. In the present paper, we try to build on the outcome of the preceding one and verify the general validity of the Economic Vitality evaluation method for other regions in Japan as well. In particular, we propose to make a seismic risk assessment for Tokyo Bay region pursuant,to the evaluation method. Specifically, we intend to show that we can evaluate a seismic risk by sizing up a possible decline in the Economic Vitality index from the normal level when an earthquake strikes. We finally try to compare our own seismic risk assessment with an earlier similar assessment made by Tokyo Metropolis pursuant to a conventional evaluation method, thereby testifying to the unique effectiveness of the evaluation index of ours.

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Acceleration response spectral ratios were analyzed to examine their statistical characteristics. First, the probability distribution of the ratios was analyzed, and equations for the probability density functions, mean values, standard deviations, and percentiles were shown. Second, the above-mentioned statistics were estimated using accelerometer arrays of the Chiba and SMART-1 databases. Then, the relationships between these statistics and the station separations, frequencies and damping ratios were analyzed. Finally, based on the 50^<th> and 95^<th> percentiles, the differences between the response spectra at two different sites due to future earthquakes were discussed.

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This paper presents extended generalized Maxwell models for two types of nonlinear viscoelastic dampers. The models consist of a generalized Maxwell model to take into account the frequency-dependent mechanical properties of the damper and nonlinear hysteretic springs to simulate the softening and hardening type deflection-dependent nonlinear behaviors. For each type of the damper, mechanical properties are quantified based on a series of cyclic loading tests and then an extended generalized Maxwell model is constructed.Availability of the model is confirmed by comparing the experimental and analytical hysteretic loops, as well as time histories of hysteretic energy of the damper to which a random deflection simulating seismic effect on building structure is applied.

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An imaging radar called synthetic aperture radar (SAR) has rapidly become one of the major tools for observing the earth's surface and its change. One of the distinctive characteristics of SAR systems is their capability of recording both amplitude and phase of the backscattering echoes from objects on the earth's surface in all weather conditions, day and night, and independence of sun illumination. SAR installed on the satellites JERS and ERS observed Kobe area before and after the 1995 Hyogo-ken Nanbu, Japan earthquake. Backscattering properties such as the difference and the correlation of the backscattering coefficient called Sigma-nought from the damaged areas by the earthquake were investigated. By analyzing the time-series SAR data, we clarified that the decreasing of the values of the difference and the correlation in the hard-hit areas was due to the surface changes by the event. Then, we developed an automated method to detect hard-hit areas based on the discriminant analysis using pre- and post-event SAR images. Furthermore, the accuracy of the proposed method was verified by comparing the results from detected areas and the one of the actual damage survey.

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In this paper, a method to estimate overturning ratios of furniture during earthquakes is proposed. A curve to describe overturning ratios of rigid bodies proposed by the author et al. is used in the method. The method takes account of effects of size of furniture and friction coefficients between furniture and floors. The method is verified by comparing with earthquake damage data at the 1978 Miyagiken-oki earthquake, the 1993 Kushiro-oki earthquake and the 1995 Hyogoken-nambu earthquake. Using this method, we can estimate indoor damage due to earthquakes for various size of furniture on various floor conditions.

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Model tests of Non-displacement piles in hard cohesive soil and sand were performed in which void ratio and drained shear strength were adopted as factors. The results of these model tests and the model tests in hard clay which were published in 1998(cf.Ref. 1) led to the following conclusions,: (1) The void ratio which changes greatly the relationship between the point bearing capacity and settlement of the pile exists between 0.7 and 1,0. It is very important to the behavior of the pile tip (2)The proposed approach for estimating settlement less than about 20% of pile diameter is generally consistent with model test results.

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A quasi-static model test series using model pile and soil are performed to measure stresses and strains in the soil around the pile. A model pile is buried 250mm in the ground and loaded at the pile top. The stresses and strains in the ground are measured by pressure transducers and coil type displacement gauges. According to the test results, the following findings are obtained. In the soil around the pile tip, the resultant stress of normal stresses is act in a radial direction from a point 2.5〜3.0D(D: diameter) below the pile tip. Stress strain curve in quasi-static test is matched with that of static test.

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Many uncertainties to evaluate the subgrade reaction on laterally loaded piles still remain, especially when considering effective stress reduction in soil around piles due to pore water pressure increasing during an earthquake. The authors devised and made the appropriate test apparatus for decreasing effective stress in the test sand bed by using the seepage flow, and performed laterally loading tests in order to investigate the subgrade reaction acting on the model pile. It was found out from the experimental results that the lateral subgrade reaction on the pile at a given level is approximated by the hyperbola with respect to the lateral displacement of the pile. The initial modulus and the convergence of the hyperbola are the initial coefficient of lateral subgrade reaction and the ultimate value, respectively. In conclusion, it is found out that both of the values increase linearly with depth (i.e. triangle distribution), and decrease linearly with effective stress in the sand bed.

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In the structural design of the deformation on the timber floor and beam under vertical loads, the special considerations are required, compared with reinforced concrete and steel structures. The requirements come from joint deformation and creep behavior. In this paper, creep behavior of glulam beam, joint and frame are discussed experimentally focusing on temperature and humidity influence. The long-term creep behavior, which is estimated from short-term experimental results, is also discussed. Based on the discussion of experimental studies, following conclusions were obtained; 1) Under the non-controlled condition, the start timing influences the creep behavior. Concretely, the creep that was loaded from the end of summer or autumn doesn t increase by spring season. When spring comes, the creep increases rapidly. That means that long-term is required to evaluate creep behavior under non-controlled condition. 2) The creep behavior of joints is quick to be influenced by seasonal changes of temperature and humidity compared with beam without joint. 3) It is reasonable evaluation that a total deformation including creep is computed twice initial deformation. But the members, of which major deformation was accounted for the joint slip, should be paid attention to seasonal influence.

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This paper presents the results of experimental tests completed to investigate the relationship between earthquake-resistant property and amount of lateral reinforcement of PRC pile. 12 specimens were tested; three with diameter of 600mm and nine with diameter of 300mm. The hollow space of all specemen is filled with, the normal-strength concrete. The specimens that are models of the pile head were subjected to reverse cyclic loading under a constant axial loading. The conclusions of this study are: (1) as the amount of lateral reinforcement increases, the width of shear crack becomes small but the value is influenced by the diameter, (2) the relationship between the deformation capacity and the amount of lateral reinformcement is influenced by the ratio of thickness to diameter and the axial load, (3) the deformation capacity can be evaluated by the section analysis reflecting the concrete confinement provided by the lateral reinforcement.

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Currently, <a large amount of municipal solid wastes including domestic wastes are finally dumped and therefor the rate of recycling is not/high. Technology for the production of melting slag is being developed to assist in the recycling of these wastes. Melting slag is made from municipal solid wastes by high temperature processing, melting, and solidifying. If recycled concrete aggregate produced by the demolition of concrete structures and the melting slag may be mixed and used for RC structures, recycling both industrial and municipal solid wastes together will contribute to the reduction of the final disposal of wastes. This report conducted experiments with recycled concrete, which were made of recycled coarse aggregate and fine aggregate using melting slag, and investigated whether it could be used for RC structures in terms of the seismic performance. Experiments were conducted to examine the flexural, shear, and bond failures of RC beam members. As a result, the RC beam members of recycled concrete with melting slag showed the same seismic performance as that of ordinary concrete. This indicated that recycled concrete with melting slag could be used for RC structures in terms of the seismic performance.

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This paper proposed a method to estimate the structural performance (stiffness, capacity, failure mode and ductility) of the Reinforced Concrete (RC) frame with cast-in-place non-structural'RC walls (spandrels, sidewalls and mullions): The shear-loading tests for onestory one-span RC frame with non-structural walls were conducted to investigate the influence of non-structural walls on structural performance of the RC frame. The shear resistant mechanism of the RC frames was clarified from the test and the finite'element analysis (2-D non-linear analysis). The load-displacement relationship of the RC frame can be predicted by this method verified with the shear resistant mer.hanisms

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This research analyzes the fracture experiment result of beam-to-column connections by dynamic loading in fracture mechanics. The analysis considered the influence of the plastic constraint and the rate of strain based on the CTOD design curve requested by the finite element method analysis. It was shown to be able to estimate the brittle fracture performance of beam-to-column connections by dynamic loading with the Charpy test result and the CTOD design curve. δ c estimated from the fracture displacement of beam-to-column connections corresponds to δ c converted from the Charpy impact test result of the bond line.

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Current design rules of high strength bolted shear joints which appear in specifications such as Limit State Design Spec. of AIJ and LRFD Spec. of AISC describe different rupture modes of joints but they do not define the condition of occurrence of each rupture mode, and furthermore the prescriptions for different types of rupture mode are sometimes inconsistent. This is far from the satisfactoriness for the practitioners. This paper aims at the construction of the unified strength evaluation of bolted joints based on a simple equilibrium model of lap joint subjected to tension. The derived equations are adjusted to meet the reported test results. The condition of occurrence of each rupture mode is specified and the corresponding maximum strength of joint is predicted.

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In recent years, stainless steel is superior in fire and corrosion resistance to ordinary steel, and is widely used as a thin walled member in the structure. Its material characteristics are considerably clarified, but the structural characteristics such as tube branches are not sufficiently studied. In this paper, the structural behaviors of the thin-walled stainless steel tubes with X branch joints are investigated by both the experiment and the FEM analysis. Expanding the concept of a ring-model, yield strength and ultimate strength of the branch joint are estimated.

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In Japan, beam-to-column welded connections with scallops have been generally applied in steel structures. In case of this typical joint, the connection have geometrical notch effects and some reduction of the moment capacity in the web is inevitable. Then many types of advanced connection have been proposed since the Hyogoken-nanbu earthquake. In this study, the full scale shaking table tests were performed to investigate the improvement of beam's ultimate seismic resistance by applying the advanced type of joints. It was found that the advanced method improved the efficiency in the transmitting the stress at the section where the maximum stress occurred.

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