A series of experiments is dealt with in order to examine the determining law for first cracked flexural strength and ductility after cracking, that is ultimate flexural strength and equivalent one, of which parameters are two dimensional with mix proportions and testing span to thickness of componential specimens respectively in the two substantial conditions of using chrysotile and hydrophilically treated polypropylene fibers. The following items are clarified; 1) The law for determining first cracked flexural strength is applicable to the various cases of mix proportions and thickness of components with two kinds of fibers. 2) Ductility is observed in case of treated fibers with dependence on thickness of components.

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A new type of reinforced masonry structures has been developed in Japan on the basis of U.S.-Japan cooperative masonry research. The purpose of this paper is to propose the quality control method of the new masonry structures focusing on grouted prism strength of a composite component, and property of the quality control method is certified by using experimental data obtained in the cooperative research.

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This paper describes the relationship between ultrasonic pulse velocity and dynamic modulus of elasticity of concrete in a number of measurements obtained from the laboratory tests, the experiments of full-scaled model structures and the investigations of existing buildings. It was found there was a fairly good correlation, which appears to be univocal, between them. Influences of materials, mix proportions, strength levels, ages and moisture conditions on the relationships were very small. The regression equation of the correlation is proposed as an estimation equation for the dynamic modulus of elasticity of concrete in structures from measurements of ultrasonic pulse velocity.

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The purpose of this study is to establish the evaluation method of the fracture of framed floors under dynamic loads affected by physical bodies. First, we elaborated the gist of the evaluation method of the fracture of framed floors.Second, the apparatus for evaluating the fracture of framed floors was newly designed and manufactured. Based on properties of dynamic loads affected by physical bodies, the apparatus is composed of mechanical loading system investigated in part 1 and a dial gauge for measuring framed floor bending. Third, we investigated the relation between mass and velocity is interchangeable on the experimental basis. As a result, in this paper part 2, we presented the evaluation method of the fracture of framed floors under dynamic loads affected by physical bodies using mechanical loading system.

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The complexity of the current formulas of second-order reliability method (SORM) has become a obstacle of their application. In this paper, using the simple parabolic approximation of performance function, a very simple second-order reliability index is suggested and a judge formula of curvature range for which FORM is accurate is proposed for easy practical application of SORM in structural engineering. By the proposed approximations, SORM can be easily applied without rotational transformation and eigenvalue analysis of Hessian matrixes. From several computational examples, the simple second-order reliability index proposed in this paper is shown to be simple and accurate among the existing SORM formulas of closed form, and can generally provide good approximations of exact results for a large range of curvature radius, the number of random variables and the first-order reliability indices.

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In controlling seismic responses of building structures, there are many points to be duly considered for the safety of structures and the stability of controller. In this study, three points were mainly discussed for stable control experiments; structural identification, model reduction and AMD capacity. Firstly, subspace identification method was adopted for the identification of the specimen structure, due to the ability of providing accurate state-space models for multivariable linear systems directly from input-output data including measurement noises. Secondly, in order to prevent the spillover phenomenon caused by model reduction, the specimen structure was modeled to a 2-degree-of-freedom system by using internal balanced realization reduction method. Finally, the control algorithm with variable gain was derived in order to use efficiently AMD system under the constraint condition of AMD stroke. The seismic response control experiments were performed using a 5-storied building structure model consisted of H-shaped steel beams and bearing rubbers with about 2tonf weight on each story.

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This paper shows the method of an active seismic feedforward control and forward prediction of seismic wave by use of Butterworth bandpass filter. The purpose of this study is to improve the structural response control against earthquakes and the precision of forward prediction of seismic wave by bandpass digital filter. Simulation analysis in multi-degrees of freedom system having active tendon devices is used to clear the usefulness and the characteristics of proposed method. It is concluded that the proposed method has more effective control efficiency than stationary feedback prediction control as a system taking account of time delay of control force.

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A direct 2.5 dimensional boundary element method is applied to evaluate ground motions in two-dimensional sedimentary basin due to a three-dimensional Haskell-type fault to estimate the amplification characteristics of the ground motions in the heavily damaged belt zone in Kobe City during the 1995 Hyogo-ken earthquake. We have utilized the Green's functions for an elastic half-space medium to formulate boundary integral equations in terms of displacements and tractions at the medium interface. The effects of different types of cross-section of the sedimentary basin on the strong gound motions in the basin are examined in detail.

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This paper proposes a procedure to identify the main rupture areas of heterogeneous fault models for strong-motion estimation by using the distributions of seismic moments. The heterogeneous distributions of slip amounts, average slip velocities, seismic moments, average moment rates and short-period level factors on fault planes, which were evaluated by using the data of slip vectors and their time histories during fifteen inland earthquakes and six subduction earthquakes, are studied. The main rupture area, a large-moment area having 70% of the total seismic moment, occupies about 35% of the total fault area on an average. The values of fault parameters mentioned above averaged in the main rupture area are twice as much as the ones averaged all over the fault.

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A stability ratio was applied as an index expressing the P-Δ effects in inelastic earthquake response. The stability ratio includes the characteristics of the vibration system and the amount of energy exerted by an earthquake. The P-Δ effects in inelastic response cause the concentration of plastic strain energy into one side and the increase in ductility factor. The degree of the concentration and the increase can be estimated using the stability ratio as an index. The validity of this estimation method was verified by carrying out inelastic response analyses using SDOF models and MDOF models.

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We estimated stress drop and fmax of subduction earthquakes using strong motion records observed at deep boreholes in Iwaki and Tomioka in order to evaluate high-frequency strong motions. The estimated fmax has no correlation with seismic moment. On the other hand, we found that the stress drop is proportional to fmax^<-3>. Although the level of stress drop depends on source regions, this relation is appricable to each source region. By substituting this relation to ω^<-2> model, we show spectral amplitudes of acceleration source spectra in the frequency range higher than fmax are scaled by only seismic moment.

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In this study, the method for quantitative loss estimation of household property due to an earthquake is proposed. The value of household property owned by a family depends on income, family members and regions. The model of household property is established. Combining the model with the vulnerability functions of household property, the loss of household property for the hypothetical earthquake is estimated. The validation of the method is perform by comparing with the payment of earthquake insurance in the Hyogo-ken Nanbu Earthquake. Finally, the quantitative loss evaluation of household property for the hypothetical earthquake in the Kanto area is performed.

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A beam-column finite element model composed of several fiber segments is proposed to predict the large deflection behavior of spatial rigid frames. The basic equations are developed on the basis of the beam-column finite element method using the incremental perturbation technique. In this paper, the elasto-plastic lateral buckling behavior of H-shaped beams is analyzed. The results of analysis predict with accuracy the moment-displacement relationship obtained from experiments. The magnitude of torque adopted as imperfection influences the strength. The residual stress sensitively affects on the strength and deteriorating behavior. On the other hand, the shear modulus in plastic range does not affect.

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For the safety maintenance of excavations during basement constructions, deflections and stresses of the temporary earth retaining walls are analyzed statistically using the 97 data in the Keihanshin district and its vicinities. Main conclusions are as follows. 1. The supervise values on deflections of temporary earth retaining walls are less than 4cm in 80% construction sites. 2. The estimated values can not be accurate enough to the measured values. 3. The construction sites that the equivalent mean N value is more than 18, the supervise values ratio are less than 1.0. The others are more than 1.0.

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The purpose of this paper is to investigate the interactive effects of mutual modes of a spherical dome subjected to harmonic excitation in anti-symmetric state. The minimum intensity of the excitation which induces the unstable resonance in single modal state is presented first, in which the geometrical and material parameter of the shell and the parameter due to damping co-exist in the form of multiplication. Multi-modal states, then, are examined and the variation of the region of the unstable resonance is clarified in comparison with single modal state.

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Tension strings are useful for stiffening structures with minimum material, and are even able to be treated as compression members when prestressed forces are introduced. If practical damping-systems for these strings exist, they will enlarge design freedom by reducing and stabilizing structure's response against seismic or wind forces. In this paper, viscoelastic material with elastic spring is studied as additional damping-system connected directly to strings and keeping their prestressed forces. The basic characteristics and effects of this damper are discussed using the simple Kelvin-Voigt model, followed by checking the response against conventional time-analyses.

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This paper deals with structural analysis, experiments and estimation of seismic performance of bolted glulam frame structures with plywood shear walls. Full-scale loading tests on the 2-story plane frame structures of bolted glulam semi-rigid joints with plywood shear walls were performed, and the seismic behavior and analytical methods of these structures were investigated. The finite element method, the beam theory on the elastic foundation, the model of semi-rigid joints, equivalent brace of nailed plywood panel and gap elements for joints of shear walls and frames, are applied to study of these structures. The results of experiments showed the excellent seismic performance of these structures, while the results of analysis showed good agreements with experiments. The equivalent brace method is able to apply for the practical calculation of these structures. This study indicates the possibility of widespread development of these structures and the application of these analytical method.

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The strength of gas-pressure welded joint has been assumed as strong as the strength of the base reinforcement. However, many gas-pressure welded joints were breaked in RC and SRC structural buildings during the 1995 Hyogoken Nanbu Earthquake. After earthquake, we picked up 365 test pieces of gas-pressure welded joints from the damaged RC and SRC structural buildings, and those pieces were tested by the tension test. The 12.6% pieces in all test specimens were breaked at welded joints. Therefore, the strength of gas-pressure welded joints in the existing concrete structural buildings are not able to apply the present evaluation. This paper is a study on the strength distribution of gas-pressure welded joints. The strength distribution of gas-pressure welded joints were researched by the data of Hyogoken Nanbu Earthguake and another test data of 23 public experiment institutions in Japan. From the research of this study, we took mainly the following conclusions. (1)The strength of gas-pressure welded joints used in the existing concrete structural buildings were not evaluated as strong as the strength of the base reinforcement. (2)We proposed the probability distribution function of strength for gas-pressure welded joints used in the existing concrete structural buildings.

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In this study, steel frames subjected to horizontal and vertical ground motions simultaneously were analyzed dynamically with considering the strength deterioration and the effect of vertical ground motion on the collapse behavior of steel frames was investigated. The axial force and the natural period of the frame in the vertical direction were specified as main parameters and it was found that a critical axial force for converging the accumulation of damage and a relation between the natural period of frame and the predominant period of ground motion had an important role in the response under horizontal and vertical excitations.

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Beams and beam-columns of many steel frames fractured in a brittle manner in the 1994 Northridge Earthquake and the 1995 Kobe Earthquake. In this study, the cracking and the following brittle fracture of rectangular steel tube beam-columns and H-shaped beam-columns subjected to a tensile axial force mainly and the repeated horizontal force were investigated by tests and analyses. Initiation of cracking at the place by a welded part of the beam-column to the base plate and its rapid propagation up to the fracture could be predicted qualitatively well by the critical axial force-axial displacement curve for convergence of the damage accumulation proposed before.

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Premature rupture of beam flanges at the vicinity of beam-to-column moment resisting connections of steel structures were widely observed in the 1995 Hyogoken Nanbu earthquake. This paper defines, firstly, the basic requirement which the beam-to-column connection should meet. Then the proportioning of end connection details to satisfy the requirement is analysed, and using the information from the test results hitherto reported, a design criterion to prevent the premature rupture of beam end flange is proposed.

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Various testing methods for accelerated delayed fracture have been proposed. In 1980, a method was showed as JIS draft, however, any methods is not confirmed now. In our former paper, we proposed newly devised test method, that is, alternate immersion cycle in sulfuric acid solution accomplished by subjecting the solution for period of 10 minutes per hour, followed by drying in air for a period of 50 minutes. Further, we showed the discrimination between fracture and non fracture bolt, through the test results applying our proposed test method. In this paper, we carried out 3 kinds of the other test involving JIS draft using the fractured and non-fractured bolts in our former test, as specimens. Through this experiment, we made it clear that the influence of testing manner on the results of bolt fracture showed not always the same situation due to the test methods.

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Since the strong horizontal force occurred in earthquake often causes cumulative damage such as the strength deterioration and the accumulation of deformation in structures and their members, the prediction of cumulative damage is needed in an aseismic design of structures. In this study, the critical axial force for convergence-axial displacement curves of RC and SRC beam-columns are proposed as a characteristic curve for repeated loading in order to predict the cumulative damage. Tests and analyses of RC and SRC beam-columns were carried out and it was found that the cumulative damage could be evaluated by the curves very well.

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In this study, the effects of loading direction on the flexural behavior of concrete filled square steel tube (CFT) are experimentally studied. The selected test parameters are loading direction and eccentricity of axial load. As the result, It was indicated that the flexural stiffness and axial stiffness of CFT column subjected to bi-axial bending could be evaluated by the equivalent stiffness of the concrete elastic stiffness with that of the steel tube regardless of the loading direction, the same as the case under the uni-axial bending. The ultimate strength curve of CFT column subjected to the bi-axial bending was ascertained, and its evaluation formula was proposed.

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This study aims to estimate seismic risk potential in Tokushima Prefecture. For this purpose, it is necessary to take account of faults that may affect the region. Because high damage districts differ depending on which fault becomes active. So we analyzed estimates of damage to buildings and probabilities of occurrence on the assumption of three cases of earthquake, and evaluated seismic risk potential. The result indicates that in addition to districts that have inherent risk against earthquakes, districts near the strained faults are high potential. Districts around active faults in northern Tokushima were found to have particularly high risk potential. This finding may offer a useful index in selecting districts that should be given priority in preparing for disaster to mitigate damages.

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This paper presents fragility curves for buildings based on damage data due to the 1995 Hyogoken-Nanbu Earthquake. The fragility curves in terms of the structural type and construction period were constructed using the building damage data of Nada Ward surveyed by Kobe City for the purpose of property tax reduction. It was also demonstrated that the number of damaged buildings in Nada Ward estimated by the fragility curves fits the actual damage by the earthquake. The fragility curves thus obtained may be useful for damage assessments of buildings in Japan.

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Tokyo Metropolitan Government recently published "The Earthquake Area Vulnerability Assessment of Tokyo". It shows relatively dangerous zones in Tokyo. In this paper the method for building collapse risk used in this report was applied to the Nada Ward in Kobe City using building inventory before the 1995 Kobe Earthquake. The obtained "building collapse risk" was compared with the actual damage of the ward due to the earthquake and a revised method to evaluate "building collapse risk" was proposed. The new building collapse risk corresponds to the ratio of building collapse and it reflects the characteristics of buildings and grounds.

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This study is an investigation for the buckling and post-buckling behavior of alminium alloy thin plate under compression. Compression tests of box-section stub-columns were conducted as the representative of thin plate and test results were compared with the concept of effective width by Karman, Winter and AISI. Furthermore experimental results were compared with the results by widely used FEM analysis. It is confirmed that the application of this FEM analysis is fully sufficient to develop widely for another stress conditions. The authors propose the conservative equation to estimate the effective width.

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