Analyzing the seismological and damage data of the Tangshan earthquake, we derived a function correlating the percent loss of masonry buildings to that of human lives. We determined the relationship so that the spatial distribution of the death estimated on the basis of the relationship was the most consistent with that of the data. We employed the method of system identification in this determination. The relationship obtained was a downward-convex, monotonously increasing function having a fatality rate of 30% at a collapse rate of 100%.

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The construction of Yamanashi test line for super conducting magnetic levitation vehicle system (Maglev) is advancing, and Maglev is planned to be adopted for Chuo-Shinkansen. Austemtic high manganese steels are intended to be used for the structures. In this study, the fatigue crack propagation rate of this type of steel and the influence of stress ratio and residual stress on this rate are experimentally investigated, and the results are compared with those of carbon or low alloy structural steels. On the basis of the above examinations, the expression representing the rate is proposed.

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The extension of the elastoplastic constitutive equation so as to describe the dependency of the direction of a plastic stretching on a stress rate or a stretching is one of the most important but unsolved problems in the elastoplasticity To this aim various flow rule models have been proposed in the past. A pertinent model has not been proposed yet, however, as reviewed in this article. Then, keeping a single smooth (regular) yield surface for the steady development of the elastoplasticity, an extended flow rule is proposed by incorporating an additional term of the stretching in degree zero into the associated flow rule, which is capable of describing that dependency fulfilling the mechanical requirements, i. e. the continuity condition and the work rate-stiffness relaxation. Based on it, a constitutive equation of metals with the isotropic-kinematic hardening is formulated, and its mechanical response is shown by numerical experiments.

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The subject of this paper is to analyze the stress function near the interface crack between dissimilar anisotropic composite materials. The character of this study consists in creating a pair of process zone which contains open-displacements and stresses at the crack tips. Then, oscillatory stress singularities at the crack tips vanish and the smoothed stresses and displacemets for arbitrary angle of principal axises are obtained. This proposed method may be more practical for analysis of the fracture of dissimilar anisotropic composite materials and rocks.

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A simply-supported rectangular plate subject to a pure bending undergoes successive hierarchial bifurcation. The bifurcation structure of this plate arises from the “hidden (circular) symmetry” of the periodic nature of its displacement. We will arrive at this structure by means of the concept of irreducible representations in the group-theoretic bifurcation theory. The boundary conditions are revealed to significantly alter the bifurcation structure.

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This paper proposes a unified and efficient new optimum design method for linear and nonlinear truss structures which is developed on the bases of energy principles and without behavior sensitivities. By using the principle of minimum complementary energy and the Lagrangian interpretation, the necessary conditions for structural analysis problem are derived, then the primary optimum design problem is reformulated considering both the primary design constraints and the necessary conditions for analysis problem derived above. In the reformulation of optimum design problem, structural behaviors are also considered as the design variables in addition to the cross-sectional areas of member elements. This reformulated optimum design problem is solved by using the sequential linear approximation concept and a modified linear programming algorithm, however, in the optimization process no behavior sensitivity are used. The generality, rigorousness and efficiency of the proposed optimum design method are shown by several numerical design examples of statically indeterminate trusses.

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A new approach is presented for predicting the ultimate strength of plates subjected to biaxial in-plane forces. Experimental studies are conducted on the ultimate strength of plates subjected to not only uniaxial but also biaxial in-plane forces. It depends on the thickness of plates and the ratio of stresses applied whether the elasto-plastic buckling or the elastic buckling occurs. Two parameters σ and R* are introduced to predict the ultimate strength of plates. Both experimental and numerical results are used to show the validity of the new approach. Although the present approach is easier to apply than other available approaches, it provides consistently good predictions.

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Sixteen cantilever steel box column specimens modelling steel bridge piers were tested under a constant compressive axial load and cyclic (quasi-static) and monotonic (static) lateral loads. The purpose of this experimental study is to investigate the influences of the important parameters such as width-thickness ratio, particularly slenderness ratio and cycles of loading on the strength and deformation characteristics of steel bridge piers. Ductility and energy absorption capacity are also discussed in view of the effects of width-thickness ratio and slenderness ratio.

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A method to find the relationship between local stresses caused fatigue damage at the connection details in steel bridge structures and displacements of bridge members were proposed. By applying this method to three typical damaged crossing details, the arising mechanism of local stresses were investigated.

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An ultrasonic inspection system that can manipulate the angle of probe was applied to perform aperture synthesis by ultrasonic waves. It was demonstrated that aperture synthesis method gave better resolution for imaging the inner flaw than B-Scope method.

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A formulation of probabilistic back analysis is proposed, for a system of unknown parameters of normal distribution or lognormal distribution. The validity of the proposed methodology is shown by solving a same problem discussed by other researchers. It is pointed out that specific accuracy of observation is required to obtain exact estimates, and that the relation of the resolution of observation error to estimate error can be evaluated qualitatively. An effective algorithm in term of total calculation time rather than the number of iteration is proposed and demonstrated through numerical calculations.

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A direct integration scheme to compute dynamic response of structure with nonlinear stiffness property is proposed. This method utilizes and combines the advantage of the Central Difference Method in accuracy and that of the Averaged Acceleration Method in unconditional stability, which does not require the iterative calculations. Numerical analyses are conducted to examine the usefulness and validity of the proposed method in nonlinear dynamic response analyses using Finite Element Mlethod. The proposed method is stable in calculation due to the high damping property in higher frequency range and the high accuracy in lower frequency range.

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Layered solid-fluid media were analyzed by a thin-layered element and discrete wave number method. The scalar wave equation for the pressure of the fluid was employed to introduce the effect of the compressible fluid. The thin-layered element method was applied to both the elastic wave equation of solid as well as the scalar wave equation of fluid. As a result, eigen value problems of non-symmetrical matrices were derived. Green's function was calculated by superposing the eigen solutions of the non-symmetrical matrices. Several investigations were applied to the numerical solutions to examine the validity of the present method.

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This paper proposes a prediction control rule based on an optimal control algorithm and an instantaneous optimal control algorithm. And to compensate the time delay of control force, prediction methods on the input earthquake motion and the responses of a multi-degrees of freedom system (MDOF) is developed. Especially, in case of the MDOF, all responses can not be observed in general. So, using only a few points' observed information which includes the observation noise. all responses can be predicted accurately with this proposed method. And simulation analyses are demonstrated to show the usefulness and the characteristics of this method for the model system which are installed with active-tendon devices.

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Shaking table tests of a quarter scale model bridge with sliding type isolation system were performed. The isolation system is composed of a sliding bearing and a rubber restoring force device. As a result of the shaking table test, the following advantageous characteristics have been clarified: 1) The shear force of the pier can be considerably decreased by using the isolation system. 2) The isolation system should be designed so as to limit the sliding displacement before the stopper functions. The use of high friction material and stiffer restoring force device is useful. 3) The residual displacement, in most cases, is small enough for the practical design. 4) By using sliding material of different friction coefficient. and selecting the stiffness of restoring force device, the distribution of the shear force to each pier can be changed.

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In case of performing a response analysis under severe earthquake ground motion using a hysteretic model, the information of restoring force characteristics of real structures is necessary. The purpose of the hybrid test (on-line computer-controlled experiment) is to obtain the responses with a combination of numerical analyses and model tests. The authors consider three hybrid test procedures taking account of the scale factor between prototypes and models, and carry out hybrid tests and numerical simulations using each procedure. As the result, it is found that the responses with three procedures are almost identical.

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Based on questionnaire surveys conducted in Tokyo area, seismic damage mitigation measures for art objects and artifacts in museums are discribed. Some representatives of the measures are then characterized in detail by vibration experiments. Finally, the performance of a compact base-isolated display stand which is a newly designed device suitable for the exhibition of the objects is experimentally evaluated with satisfactory results.

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For the design of concrete containment structures built in nuclear power stations in Japan, internal pressure, temperature load and earthquake load have so far been considered as the major types of load that could result from accident. In some foreign countries, impact load caused by collision of missile is taken into consideration for the design of this kind of structures as well. Also in Japan, in the design of the repossessing plants which is now under construction at Shimokita area, air craft crash is taken into account. In this study, in order to establish the design method of concrete structures against impact due to collision of missile, the impact tests have been carried out using hard missike with the velocity from 4.0m/s to 250m/s. Based on these results, we proposed the design method of reinforced concrete structure against the collision of hard missile.

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This paper describes digital simulation methods of strong earthquake ground motions using a seismological model. The methods described in this paper are based on the spectral representation of stochastic wave in conjunction with the seismological stochastic source model with ω^-2 property and the representation theorem of elastodynamics. Numerical examples demonstrate an applicability of the proposed methods into prediction of strong earthquake ground motions in areas where strong-motion data are sparse.

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During the 1930 Northern Izu, Japan earthquake (M=7.3), a torpedo exhibited at 7.5km from the epicenter was forced to slide against supporting rocks. As a result, a series of remarkable scars was left on the painted face of the torpedo. Based on the scars, the near-field strong motion characteristics were estimated by using available documents, laboratory vibration experiments and numerical simulations.
The results showed that the maximum earthquake intensity was in the range of 1.2-1.7m/s in velocity and 13-20m/s/s in acceleration, and that duration of the strong motion was about 10sec or more during which at least seven peaks exceeded 0.7m/s and 8m/s/s.

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A probabilistic method to evaluate the seismic risk of urban lifeline network systems is presented with emphasis on the aspect of system interactions among lifelines. First, the outline of interaction-related problems in lifeline earthquake disaseter is discussed. Next, the probability of system malfunction due to functional damage propagation and the damage to the system itself is assessed. System interaction is quantified on a probability basis in terms of four kinds of importance factors, which can be conveniently used to compare effectivity of alternatives of earthquake disaster countermeasures. An illustrative example of seismic risk assessment of water supply system is presented, taking into account impact of electric power failure.

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We developed a method for estimating seismic supply reliability of electric power transmission system. At first, we proposed an algorithm for reliability analisis of power system by simulating electric power flow control after earthquake. Secondly, we showed this method is more effective than other existing methods using 22 node model of IEEE. Finally, we applied this method for Memphis electric power system in USA and showed it is effective for real construction planning of electric power facilities.

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Modern societies heavily rely on electric power. These societies will suffer from functional losses resulting from power outage when natural disasters such as earthquakes and typhoons strike. A database which consists of regional characteristics and electric power demands in the Tokyo Metropolis was constructed using a geographic information system (GIS). As the first step of evaluation of the effects of power outage, the power demands were examined as a function of time, season and region. Four typical power load curves, which correspond to residential, office, factory and entertainment regions, were found. The power load curve of each region served by a distribution substation was then considered to be a combination of the four elements and the contribution rates were evaluated.

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A questionnaire survey was conducted to 1, 000 households of Kushiro City two months after the 1993 Kushiro-Oki Earthquake. The results of the survey show that about 50% of houses suffered structural damage to some extent. Ratios of overturning of furnitures and breakage of lights exceeded 20%. The damage ratios on hilly and sloping grounds are higher than those on level grounds. Service stops of lifeline systems occurred after the earthquake: 48% for electric power, 33% for water and 22% for city gas. It was found that the duration of service stop is an influential factor to residents' inconvenience. Customer's tolerance time for service stop was the shortest for power and the longest for gas.

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The main towers of the Akashi Kaikyo Bridge are about 300m high and have very flexible futures. So the vibration of the towers due to the wind is one of the most important problem not only during construction but also after completion of the bridge. The shape of cross section was improved to stabilize the divergent torsional vibration at high velocity, and Tuned Mass Dampers (TMDs) are installed to reduce the amplitude of the vortex induced oscillation caused by the wind slower than the design wind speed both during construction and after completion of the bridge. In the report, the outline of vibration control of the towers of the Akashi Kaikyo Bridge is reported.

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A reconnaissance survey was conducted to Guam Island after the 1993 Guam Earthquake of magnitude 8.1. Ground acceleration was estimated baced on a source model. Ground failure and liquefaction were observed but were limited to some areas. Although roads and bridges had little damage, some reinforced concrete buildings and power plants had significant damage. Power outage occurred for a few days and affected the operation of deep wells of water system. Since Guam is frequently attacked by typhoons, the effects of the earthquake was minimized due to its well-preparedness to natural disasters.

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On January 17, 1994, the northern part of Los Angeles, California, was heavily shaken by the Northridge earthquake of surface magnitude 6.8. The earthquake had significant effects on residential and commercial buildings and lifeline facilities. This paper focuses on the damage and restoration of electric power facilities. In particular, damage of power facilities by the 1994 Northridge earthquake was compared with that by the 1971 San Fernando Earthquake. Current earthquake resistant practices on the substation equipment both in Japan and USA were also carefully examined. As a result, the effects of revision of earthquake-resistant design criteria for substation equipment were observed. The damage to substation equipment in Japan is expected to be less than that in USA, even if the same level of acceleration as the Northridge Earthquake occurs in Japan.

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