The prediction of the effective properties of heterogeneous materials is of primary importance in design or analysis. For statistically nonhomogeneous materials, the prediction is laborious since the effective properties vary depending on various conditions. This paper presents a method of estimating bounds for all possible effective properties for given limited information. Considering permeable flow through rock mass as an example, the bounds are rigorously derived and are compared with ranges obtained from numerical simulation of heterogeneous porous media. The results support the validity of the proposed method.

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On the exact equilibrium configuration of an elastic cable spanned, the potential of uniform self-weight and the strain energy in stretching are analytically estimated. Those quantities are related to the work done by the chord force into an energy conservation. By the differentiation of the energy relation with respect to the span elongation, the chord force is separated into two components reflecting the sag effect and the elastic elongation. In a numerical analysis, it is shown that a characteristic magnitude of the stretching exists between the slackened and the tightened states.

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The projection of sewerage manholes above ground has been observed during earthquakes that have caused significant soil liquefaction. The force that moves a manhole upward can be attributed to the buoyancy caused by the liquefied soil, since no other reasonable causes are apparent. The weight of the manhole and the soil resistant force are the only forces that are in static equilibrium with the buoyancy. In this paper, we discuss the quantitative conditions for the possible projection of a manhole taking into consideration the above equilibrium of forces. The results should provide information helpful in the planning of countermeasures against damage to sewerage systems caused by projecting manholes.

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A continuum theory recently proposed by the authors is applied to creep failure of hard rocks and short-term failure of granular materials. The governing equations of the proposed theory are formulated through the homogenization of an elastic body with many microdefcts. The constitutive relation of the present theory consists of the average stress-strain relation and the evolution equation of microdefects. The main feature of the theory is that the effect of interaction between microdefects is taken into account in the evolution equation. A new field variable is introduced to take into account the interaction effect and a governing equation for the new variable, which is an integral equation, is derived. Numerical results presented here confirm that the theory reproduces macroscopic failures induced by the localization of microdefects.

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This peper is to propose a method of deriving stress functions with finite stress concentration at crack tips in an isotropic and homogenious plate which is applied uniform tensile or shearing stresses, etc. at infinity. By smoothing Westergaard's solution, stress functions constructing corresponding parts of process zone are derived. In this way, 12 sets of fundamental solutions are derived, it is shown that by combining the solutions adequately or adjusting the length of process zone, finite and smooth stress concentrations are constructed and the various forms of opening displacements are expressed. Proposed functions are usably applied for the analysis of numerical simulations for fracture or development of cracks in concrete or rock.

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This paper studies the elasto-plastic dynamic behaviors of steel cantilever columns with variable cross-section subjected to horizontal earthquake ground motion An analytical procedure based on the implicit time integration technique is developed for columns with multi-degrees of freedom The numerical results aimed at the collapse patterns of columns indicate the coupled behaviors between sway and vertical vibration as well as change of collapse patterns due to Pδ effects. It is concluded from the efficiency of the absorbed strain energy corresponding to cumulative plastic strain every cross-section that the favorable collapse pattern from a point of seismic design view is to restrict the plastic deformation within the lower cross-section of columns.

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Steel diaphragm walls with very high horizontal rigidity, can be constructed by filling up the steel elements which forms strong joints with concrete. In order to design details of the horizontal bending rigidity it is necessary to understand quantitatively the behaviors and strengths of steel-concrete composite wall subjected to out-of-plane bending moment. For this reason, the experiments on the strength of some beam specimens subjected to out-of-plane bending moment have been carried out.
The steel-concrete composite diaphragm walls can be designed as the bi-directional walls when horizontal joints of steel elements are welded. Although the steel-concrete composite diaphragm walls, when the horizontal joints are not welded, can be designed as the walls with high strengths, it is required to calculate the deformations.

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In order to make clear the fatigue strength evaluation method for load-carrying fillet welded joints failing from weld roots, fatigue tests on the joints with fillet welds of various shapes (isosceles triangle, two types of scalene triangle, concave, convex) have been carried out. Fatigue crack propagation analyses have been also performed for the tested joints and one hundred models of the joint. On the basis of experimental and analytical results, the influence of weld shape, weld size, weld penetration and plate thickness on the fatigue strength are made clear, and then, a numerical expression of weld throat is proposed for evaluating the fatigue strength.

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The C-scan images of artificial defects in a steel plate with 9mm thickness are obtained by an ultrasonic inspection. The quantitative waveform analysis on the echos is performed for the estimation of reliable size and inclination of a defect. Two types of specimens are used. In the first type two specimens which have a channel type of groove defect with different depth, are used. In the second type a steel plate specimen with 9mm thickness which has twelve artificial defect holes drilled with different depth, diameter and inclination, is used. By using an immersion type of transducer reflection waves returned from a defect are detected and stored on floppy disk. Those are used for waveform and spectrum analysis to get more accurate and detail information on defects. It is shown that 3D display/rotation of reflection wave using graphic software of a workstation is very helpful for a precise waveform analysis of a reflected echo.

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Evaluation method in maintenance inspection of a bridge is proposed by appling a computer graphics and a quantification method in this paper. Total evaluation of a bridge integrity is divided into two sub-evaluations of mechanical and functional evaluation. Thirty two sets of data for actual bridges are used and the results in quantification analysis are shown in 3D rotation of computer graphics

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The purpose of this study is to investigate the commonness and difference between seismic responses of 3-dimensional structure-pile foundation-ground systems and those of 2-dimensional systems. In performing the 2-dimensional FEM analysis, the determination of thickness of the ground model is one of the most difficult problems. We obtained the optimum ratio of the thickness of ground to that of foundation structure which give the least difference between 3-D and 2-D analysis by performing parametric analysis by changing the number of piles and the height of structures. The results indicate that the responses of 3-D structure-pile foundation-ground systems can be estimated from the responses of 2-D systems by introducing correction coefficients. The coefficients were almost constant according to the number of rows of piles irrespective of the height of the structure.

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Numerical solutions of elastodynamics problems are usually obtained by Newmark's method or modal analysis using eigenfunction expansions. However, Newmark's method is inaccurate for the stresses varying with discontinuity, and the modal analysis is hardly applied to complex problems. While wave propagation problems are generally solved with analytical method using a Laplace transform, the Laplace inversion is hard to do. There are many studies on numerical approach for that reason, but numerical accuracy of these methods has not been well evaluation and discussion. In this paper, the normal and inverse of numerical Laplace transform using the fast Fourier transform are studied, numerical solutions for elastodynamics problems are presented by the Finite Element Method and a numerical Laplace transforms. A few examples are presented to show the accuracy of the proposed method.

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Variable Dampers which change the damping characteristics depending on the bridge response is proposed. Effectiveness of the variable damper for seismic response control of bridges is studied through a numerical analysis. A prototype variable damper was developed, and a series of dynamic loading tests were made to verify the effectivenss of the variable damper. A series of shake table tests were made using the prototype model. Effectiveness of the variable dampers for seismic response control of bridges was verified by the shake table test. Analytical simulation provided a realistic response prediction of the response of the model bridge.

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In case of introducing seismic isolation system to bridges, relative larger displacement responses of girders must be expected during major earthquake. Knock-off devices are practically used in New Zealand, which were designed to absorb collisions between base-isolated bridge girders and abutments. In this paper, a new type of knock-off device to deal with traffic conditions in Japan is proposed and confirmed its functions through 1/2-scale model experiments. Yield mechanisms of its backfill ground is studied by non-linear FEM simulations. A practical method to calculate its critical strength is proposed.

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Measuring bridge cable tension by a so-called vibration method is very convenient. However, to estimate the tension from low frequency modes, excitation often becomes necessary. To improve the method, this paper presents a method for estimating cable tension from high frequency modes by the exact solution of the cable vibration considering the effect of flexural rigidity, cable sag and inclination of the cable. Using a personal computer, the tension can be estimated on site by micro-tremor method exactly and speedily.

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Based on both the numerical simulations and the theory of elastic waves, we proposed the simple formulation which can predict site response affected by topographical irregularities in the form of design spectra. In order to verify the site response predicted using our proposed formulation, the results from two dimensional earthquake response analyses conducted concerning two types of topographical models, the basin and the inclined base layer, and previous studies were compared with them.

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When structures are subjected to a large ground motion, residual displacement is developed associated with nonlinear hysteretic behavior. Excessive residual displacement is harmful for repair of the structures after an earthquake. The residual displacement developed in an oscillator with bilinear hysteretic restoring force model was analyzed for various ground motions, and it is proposed as “residual displacement response spectrum.” After clarifying the effect of earthquake magnitude, epicentral distance and ground condition on the residual displacement response spectrum, the design value of the residual displacement response spectrum is proposed.

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Torsional deformation of shield tunnels is important for seismic design when they are rigidly connected to other structures. Failure mechanism is important for estimating nonlinear hysteretic behavior of shield tunnels subjected to a significant earthquake. There are however few studies on the deformation and failure mechanism of shield tunnels subjected to alternative torsional deformation. A series of loading tests for two shield tunnel specimens subjected to alternative torsional moment was conducted. Presented in this paper are failure mechanism and deformation characteristics of shield tunnels with and without secondary lining.

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Accurate prediction of earthquake response of arch dams is necessary for reliable evaluation of safety of the dams. The finite element method is now commonly used for the dynamic response analysis of dams. In that case, appropriate modelling should be done to get trustworthy results, and it is important to validate the modelling of dams by comparing computed results with observed ones. In this paper, responses of an arch dam to vibration tests are simulated using a newly developed computer code for three dimensional dam-foundation rock-reservoir water system. Extensive parametric computations are conducted, and the results are correlated with test results. Appropriate modellings for vibration tests are discussed, and a recommended procedure to determine modelling parameter is described.

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A formulation of probabilistic back analysis considering uncertainty of known condition is proposed, and the validity of the proposed method is demonstrated through the numerical example. Depending the uncertainty of the apriori information, model parameters should be classified into known parameters, known parameters with uncertainty or unknown parameters for an effective back analysis. The reliability of parameters determined by back analysis may be evaluated in the form of aposteriori covariance matrix, and the reliability of forward analysis with the apriori and aposteriori model can be evaluated quantatively in a probabilisitic way. Consequently, the improvement of reliability on forward estimation by back analysis may be evaluated quantatively.

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Applicability of the super elastic alloy to the seismic dampers was discussed analytically using the numerical simulations. Super elastic alloy restores from more than 10% strain without residual deformation. Seismic behavior of the damper made of super elastic alloy was compared with that of the conventional elasto-plastic damper. The results showed that the maximum responses of the super elastic damper became 20% larger than the elasto-plastic damper. However, the super elastic damper became zero deformation after the earthquake responses while the elasto-plastic damper showed residual deformation of four times as large as its yield deformation. Furthermore, the super elastic damper could absorb 2/3 hysteretic energy to the elasto-plastic damper. The super elastic alloy would be applicable for the case that the residual deformation is critical.

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