This study aims to obtain basic knowledge of predicting the life of power reactors. To this end, biological shield concretes in Japan Power Demonstration Reactor (JPDR) exposed to radiations under long term operation was inspected in terms of hydration behavior and microstructure, and compared with model specimens cured under the same thermal conditions. Major findings are as follows, a. SEM observation showed that needle-like crystals in concrete exhibited greater development at the reactor core side than at the perimeter, and they had similar shapes to ettringite and C-S-H as observed in the model specimens. b. Bound water content of mortar was 5 % larger at the reactor core side than at the perimeter, whereas it was average 6.5 % larger in the model specimen. This tendency agrees well with the analysis of concrete in JPDR. c. Hydration products assigned by X-ray diffraction for the model specimens were monosulfate and calcium hydroxide, which were coincide with the analysis of concrete in JPDR. d. Pore size distribution of concrete showed larger amount of small pores at the reactor core side than at the perimeter. This tendency agrees well with the model specimens with a seal. e. Hydration and microstructure analysis of the model specimens supported the test results that the biological shield concrete undergoes no substantial changes.

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The compressive strength, the amount of Ca(OH)_2 and the pore structure of the concrete which contained large amount of fly ash as a part of fine aggregate were investigated experimentally to provide useful information on the establishment of the rational mix designing for high volume fly ash concrete. The experimental results showed that the compressive strength of the concrete increased in early age as well as in long term age with the increase of the content of fly ash which filled the voids between particles and prevented Ca(OH)_2 from big crystallization. The compressive strength of the oncrete was highly correlated with the cement-to-water ratio in the age of 28 days, on the contrary with the binder-to-water ratio in the age of 1 year. The increase of the compressive strength of the concrete in long term age, which was caused by pozzolanic reaction, was considered to result from the reduction of the amount of Ca(OH)_2 rather than the reduction of the pore volume

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We investigated the failure types of 50mm thick structural steel plates (SN490) including a weld bead line by conducting tensile tests. The testing temperature, -40℃, was selected in order to simulate the high strain rate. When the weld line made a right angle with the tensile axis, a usual ductile fracture occurred. On the other hand, when a bead line was parallel to the tension axis, brittle fracture occurred. Having a slit in the backing strip in the latter condition, the fracture stress was reduced to a yield strength level. The brittle fracture stress in the slit specimen was estimated by a simple fracture mechanics approach based on the measured fracture toughness K_<IC> (50MPa m^<1/2>), the initial crack size (6.4mm) as determined from SEM observation, and the estimate of residual stress along the weld line.

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The applicability of "Impacting Excitation Apparatus" to measurement of floor impact sound generated by walking was investigated in case of the floor covered with soft finishing material. At first, excitation forces applied by walking and the apparatus were investigated. Secondly, the floor impact sounds were measured in actual houses. As the results, it was confirmed that the forces and the sounds would be changed by the effect of soft finishing material, the frequency characteristics of the force of heel landing could be almost substituted by the apparatus, and the sounds generated by walking and the apparatus were almost the same.

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The contact thermal sensation caused by foot or buttocks contacted with floor is one of the evaluation index for the floor heating. This paper deals with the evaluation method of the thermal sensation for the floor heating. The thermal sensation of testing floors with ten types of floorcovering and four floor temperatures was evaluated by bare foot, slippered foot and buttocks. The contacting surface temperature between an artificial foot and floor was measured. The test results are as follows ; (1) The relation between floor temperature and thermal sensation is approximately on a straight line each floorcovering, and these lines crossed at foor temperature of 32℃ to 34℃. (2) The contacting surface temperature of artificial foot shows the same tendency as that of human foot. (3) The relation between floor temperature and contacting surface temperature is approximately on a straight line each floorcovering, and these lines crossed at floor temperature of 32℃ to 34℃. (4) The contacting surface temperature can estimate the thermal sensation of floor heating. (5) The comfortable range of sensation is 1.6℃ to 3.2℃ of contacting surface temperature.

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The design wind load for the structural frame of a circular flat roof has been investigated, based on the dynamic-respose analysis both in the time and in the freqency domain. In the analyes, the wind-tunnel data of simultaneous pressure measurements at some hundred points are used. The results indicate that the equivalent static pressure, which reproduces the maximum response of the roof, can be evaluated by using a gust loading factor approach. Empirical formulas for the distribution of equivalent design pressure coefficient on the roof are provided.

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In this study, the questionnaire survey on seismic damage of household property in the Hyogo-ken Nanbu Earthquake was performed. The results show that the damage area of household property spreads more widely than that of building, and that the damage ratios and patterns are different for the respective types of household property. Based on the result of the survey combined with the seismic intensity of the area, we proposed vulnerability functions that present the relation between seismic intensity and damage ratio of household property. These functions are useful for quantitative evaluation of household property damage.

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Detection of discontinuities in response of building on earthquake by using the jerk sensor combined with a vibratory gyroscope and a cantilever is reported in this paper. It is reported by authors that the discontinuities generated from the elastic region to plastic region in the observed response of structure is detected by the wavelet analysis of it. As the wavelet analysis requires the numerical computing process, it can not be used on-line monitoring. However, it is sometimes requested to detect the discontinuities to reflect the information to the feed back control. In this paper, the jerk sensor combined with the vibratory gyroscope and the cantilever is proposed to detect the discontinuities in signal on-line. The effectiveness of this sensor is proven through experiments.

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A method to evaluate interstory stiffness and damping based on ambient vibration measurements is presented. The method was applied to two steel buildings, both of which were damaged during the strong earthquake motion of the 1995 Hyogoken-Nanbu earthquake. Through comparison before and after repairs, the following results were obtained. (1) Damages to beam-to-column connections in a moment frame structure caused reduction of interstory stiffness by 20 to 30 percent. (2) Fracture of bracing members in a braced frame structure caused reduction of interstory stiffness by about 50 percent. The obtained results can be utilized as a standard reference for developments of damage detection methodology.

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This paper discusses possibility of increasing ultimate aseismic safety of steel buildings by utilizing PC curtain walls which have been non-structural members. Elastic-plastic seismic responses of the structures with and without walls are analyzed, and the results are compared to show aseismic effects of the walls. Moreover, allowable seismic accelerations of the structures are estimated on the assumption that they correspond to the beginning of strain-hardening of plastic hinges, and it is shown that the accelerations may be increased from less than about 800 cm/s^2 (without walls) to more than about 1000 cm/s^2 (with walls).

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In formulating an analysis with finite displacements for space trussed structures, the equation of equilibrium based on the Lagrangian coordinates is generally used but the method of this analysis is comparatively complicated. In this paper, we formulated the method of stress analysis with finite displacements for space trussed structures by applying the incremental equation of equilibrium based on the Eulerian coordinates and thus the procedure of this analysis is not only comparatively simplified but convenient for practical use.

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Although cables are most popular as material, steel rods are also used as tensile members in tension structures for long time in history. In this paper, required quality for the tension strings and their connections are discussed by defining tension structures as structural-system hierarchy composed of various levels of elements. Their required quality items are chosen through historical review including bridges and glass wall structures, and through their hierarchical studies using parabolic tension elements defined as sub-systems. Several type of connections for high-strength tension rods are proposed and selected for satisfying these requirements, followed by application for practical projects.

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It is recently cited that the required performance regarding function, safety, aesthetics with a balance of economy in consideration of manufacturing and construction should be indicated to the architect, the owner and the user etc.. With respect to a system truss as well, it is also necessary to indicate the required performance. This paper takes up span, form, rotational mechanism, aesthetics for the items which determine the performance of joints for a system truss, and attempts the comprehensive evaluation of joints from an economical viewpoint. These items of the required performance are enable the structural designer to evaluate the performance of the structure, to make free design.

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Applying Fourier series in a direction to a thin elastic plate, we may obtain basic ordinary differential equations for a static problem. When the equations are solved analytically, we can obtain not only solutions of static boundary-value problems but also a shape function of the plate that satisfies the basic equations. Introducing orthotropic material properties into the plate, we get the stiffness matrix and the shape function corresponding to the matrix. Adopting the shape function, we construct the consistent mass matrix of the plate. Applying the stiffness and the mass matrices to various folded plate structures composed of the plates, we demonstrate the characteristic feature of the procedure.

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During the Hyogo-Ken Nanbu Earthquake in 1995, as many as a hundred thousand wooden houses were collapsed and the heavy death toll due to the collapse of houses reached ninety percent. In this study, for a wood framed house in the stricken area, micro-tremors were measured on the second floor and on its nearby ground surface. Using these measured results in earthquake response analyses, static hysteresis loop of the resisting shear walls, rigidity and strength of the house were determined by assuming a degrading tri-linear constitutive equation. An analytical response to the earthquake is obtained employing the acceleration recorded at the Kobe Observatory as input. The results obtained by the response analyses give clear explanation to the actual condition of slightly damaged house.

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In order to investigate the effects of restraint conditions and stress concentrations on the compressive strength of concrete by three-dimensional nonlinear finite element analysis, concrete prisms with the several height/width ratios(h/w) under compressive loads were analyzed. Concrete materials were modeled as an elastic strain-hardening plasticity materials in the pre-failure region, and as an elastic and linear strain-softening materials with the concept of shear retention factor in tension in the post-cracking region. For unrestrained loading surfaces, the compressive ultimate load carrying capacities were the same regardless of the effects of height/width ratios, however, for restrained loading surfaces, the shorter the height, the higher the compressive ultimate load carrying capacity is. It is demonstrated that the compressive strength of concrete changes according to the restraint conditions.

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The object of this research is to develop an evaluation method for the relationship between shear force and deformation of shear walls. In this paper, an evaluation method for the relationship between shear stress and shear strain of shear panels is written. The summary of this method is following ; 1. The method is based on the truss theory. 2. The tension stiffening characteristic is considered. 3. Concrete compressive strength is reduced after cracking. 4. An unique evaluation method of the principal stress axis after cracking was originally developed. The analytical results by this method oresponded well to the past experimental results.

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In this study, the collapse mode and the plastic deformation capacity of 590N/mm^2 high strength steel beam with scallops connected to box column is investigated by the monotonic loading test and the numerical analysis. And the stress transfer quantity from beam web to column is investigated too. It is clear that this quantity is influenced by column plate thickness greatly and not depend on the web thickness. As a result, if this quantity is small, beam collapses with fracture. Particularly, beam that has thick web plate is easy to collapse with fracture, and the plastic deformation capacity becomes small.

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This paper describes the effects of material properties on the plastic deformation capacity of steel members. Now, mechanical properties of steel materials aren't reflected enough on the member design. So in this study, mechanical properties used to estimate the plastic deformation capacity of steel members are reexamined. As a result, it is pointed out that the stress in vicinity of yield point and the tangent modulus in the plastic region are important factor for decision of the plastic deformation capacity of steel members. Finally, estimate of plastic deformation capacity at the present are compared with estimate of plastic deformation capacity at the proposal in this study.

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This paper studied the structural capacity of connections to concrete filled circular tubes (CFT) subjected to tension or compression. A flange joint connection, a flat gusset plate connection, or a cruciform gusset plate connection is commonly used in axial force members of hollow sections. In the connections with gusset plates, the connection length of the plate which are inserted and welded into the slots of tube end would be one of the main parameters to ensure the full strength and deformability of CFT member. The paper described (1) the outline of an experiment of these three types of connections with variety of connection lengths as well as diameter-to-thickness ratios of tubes ; and (2) discussed the requirements for the connection details in each type.

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