A method to estimate the structural parameters of a small section of a structure was presented. A structure was decomposed into two substructures which were attached at a common boundary and three subsystems resulted which were the primary, boundary and secondary systems. The identification of the structural parameters was concentrated on the secondary system. Incorporating the state and observation equations of the secondary system in the extended Kalman filter, the stiffness and damping parameters of the secondary system can be estimated. To illustrate the proposed localized identification approach, a shear building was analyzed and the identification was concentrated on the first story.

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As an application of cable structures to bridge structures, a submerged floating foundation moored by four cables is studied. The applied forces considered are the buoyancy, vertical load and horizontal force partly as a model of the tidal current. In order to examine the resistance against the overturn moment action, the governing equations with geometrical nonlinearity are solved by a direct integration method. As far as the sufficiently large tensile forces are introduced into all four cables, the system shows stable and almost linear responses, which may lead to a simplified design code generation based on a simple linear theory.

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This paper presented a numerical simulation of the ultrasonic pulse-echo inspection test, which is potentially a powerful means for QNDE (quantitative non-destructive evaluation) of cracks and flaws of steel structures. The vibration equations of elastic waves for planar rectangular domains with various types of flaws are solved by the finite element method, which can represent flaws of arbitrary shapes. Normal and transverse input ultrasonic pulses are simulated by applying distributed time-varying forces on the boundaries. Wave propagation, reflection, and scattering at the flaws are investigated to draw important information on QNDE. The crack depth is evaluated based on output waves. The validity of the numerical simulation has been shown by the comparison between analysis and experiment.

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The C-scan images of defects made by drilled holes with different types are obtained and the effect of length and inclination of drilled holes on the images are discussed in this paper. The artificial cylindrical defect of diameter 1mm and 2mm were made in a steel plate specimen of 9mm thick and 3D images of these defects are obtained by using a graphic software on a workstation from the maximum amplitude data and path length data of received waves. In the detail waveform analysis of boundary and bottom echo the method to get more accurate size of defect are shown. And in order to apply C-scan ultrasonic test to a field inspection the effect of surface roughness and thickness of specimen on their images are analyzed and the modified immersion method to use a small water bag between a probe and a specimen are proposed.

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In this paper, a general definition of the accumulated effective plastic strain concept is introduced so that the two-surface model proposed by the authors in Ref. 1) can be extended easily to multiaxial stress state by combining with a proper hardening rule. In the treatment of the bounding line, the ultimate tensile stress is used as the limiting value of the bounding surface radius. In addition, the reduction of the bounding line slope is considered. Finally, the model parameters are calibrated according to the experimental data and presented. The predictions for various kinds of steels with the present model show a good agreement with the expeiimental results.

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It is an important and interesting problem to obtain averaged mechanical behaviors of multi phase composite materials. We propose an advanced averaging technique for three or more phase materials. The new technique, which we call Generalized Periodic (GP) method, borrows basic idea from two different existing schemes, a periodic structure and a self consistent method. The GP accounts for the interaction among the same phase inclusions by the model of periodic distributions, while the homogeneity of surrounding inhomogeneous matrix is assumed. Simple numerical examples show the character of GP method. GP's character is appreciable when the number of phase is relatively small and each volume fraction is large. On the other hand, when the number of phases increases, the GP's estimation of averaged behavior rapidly gets close to that of the self consistent method.

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In the current rules for stability design of steel framed sturctures, buckling stress of a member and the effective tangent modulus governing buckling are specified as functions of slenderness ratio. However, in case of analyzing buckling strength of a complicated framed structure, there are some unreasonable problems in estimating the effective length and the effective tangent modulus by the current rules. Therefore, a reasonable method for the stability design is proposed in this paper. In this method, the effective tangent motlus that gives idealized buckling stress to be used at the interaction-strength-fomula depends on acting normal stress, and the buckling stress is immediately obtained by computing the eigen value without using the effective buckling length.

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To theoretically investigate the relationship between the degree of physical damage to the lifeline system and the functional service ratio immediately following an earthquake, this paper evaluates three simple models: open and closed curve models, and a Y-shaped model. Supply points, demand points, and failures are assumed to be distributed randomly and uniformly throughout the system. The connectivity and the distance between surviving pairs of supply and demand points are presented as a function of the total number of failures.

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In this paper, two new thick node-strip elements based on Mindlin's plate theory are presented for the bending analysis of thick and thin plates with arbitrary shape, which involve 6 or 10 nodal points and 3 or 5 nodal lines, respectively. The displacement functions of the nodal points are written as ordinary two-dimensional finite elements with interpolation functions of polynomials and the functions of the nodal lines are expressed by products of interpolation functions and a polynomial series. In Mindlin's theory deflection and rotations are independent variables, and therefore, these polynomials satisfy C₀ continuity. Furthermore, reduced integration techniques are investigated for thin plate bending, and a simple and efficient intergration scheme for plates of a wide range of thickness/span ratios is proposed by the numerical results.

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Seismic force acting on embankment dams is studied by using one and two dimensional dynamic analyses. In this report, using acceleration records of actual earthquakes, the distribution of seismic accelerations in the typical dam body section is computed. On the basis of reponse computations to different input motions having various frequency characteristics, a relationship for the induced maximum acceleration with frequency charateristics of the ground motions is established.
A simplified procedure is also presented for estimating the maximum average acceleration of potential sliding masses of various depths from acceleration response spectrum of ground earthquake motions.

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A stochastic simulation theory is proposed that predicts a sample field at non-observation points conditional that simulated field coincides with sample values at observation points. The theory is a linear interpolation by Kriging which is used for the term of unbiased-least error variance estimation and the stochastic properties of the corresponding error function is made clear, and based on these properties, an effective simulation procedure of a sample field is established in a manner of a one by one expansion toward a multiply correlated field. The theory is verified in depth and in detail, and some advantages are clarified over other simulation methods.

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A procedure for calculating impulsive response of an elastic layered medium in the anti-plane wave field is presented. This procedure is based on a thin-layered element and discrete wave number method. By the thin-layered element and discrete wave number method, wave equation in the anti-plane field is transformed into ordinary differential equations with respect to time. Green's function for the wave equation is represented by the superposition of the eigen solutions of the ordinary differential equations. It is found that impulsive responses calculated by the Green function show good agreement with analytical solutions.

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Characteristics of wave propagation in a layered medium including a dipping layer at an end under incident plane SH wave are investigated. The surface responses in frequency domain obtained from the analysis with boundary element method are expanded in a series of SH waves whose amplitude are predominantly large in terms of the horizontal wavenumber. It is found that the scattering wave generated in the dipping layer propagates as Love wave in the horizontal layer and that the Love wave is generated accompanying with the diffracted wave propagating from the dipping layer to the horizontal layer.

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In order to control the direction of shield tunnelling machine effectively, system modelling has become more important. The direction control model based on predicted behaviours of shield tunnelling machine, the feedback prediction control model, was developed by applying autoregressive model to the prediction, and by applying regression model to the control utilizing the relationship between the machine's direction and biased moment by jack pattern. The feedback prediction control model has been verified to control the direction accurately based on the observed behaviours in some various ground conditions. As the results of corelation analysis between identified parameters and ground conditions, the behaviours of shield tunnelling machine have been certified to be highly related to the stiffness such as N- value and elastic modulus of ground characters.

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This paper deals with application of a gravel drain system to underground pipelines in order to mitigate their damage due to liquefaction. Pipelines' damage in liquefaction process is supposed to be caused by various factors; buoyancy, dynamic response of ground, ground deformation, etc. Two types of small scale test were conducted. The first especially focused on the settlement of ground. Test results suggest that the settlement of sandy ground improved by the gravel drain system correlated to the maximum excess pore water pressure ratio in the liquefiable ground. The second test was conducted to study the effects of the gravel drain system to performance of pipelines, and to clarify the problems which should be solved before the gravel drain system is designed for underground pipelines. The gravel drain system can reduce the settlement of ground around pipelines, and reduce the duration of vibration strains and floatation of the pipelines.

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A practical design method is proposed for steel framed structures in which bucking design under ultimate limit states poses problems. Here, improvements such as a ζ function have been incorporated in the new method to allow for simple safety verification unrestricted by the concept of the effective length. The new method was applied to actual multiple-layer frames and the efficiency of the method was confirmed.

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