A new extension for the Applied Element Method (AEM) is introduced. Using this method, the structure is modeled as an assembly of distinct elements made by dividing the structural elements virtually. These elements are connected by distributed springs in both normal and tangential directions. This paper describes the applicability of the AEM for different fields of analysis and structure types and it deals with the formulations used for RC structures under monotonic loading. It is proved in this paper that the structural failure behavior including crack initiation and propagation can be simulated accurately with reasonable CPU time and without any use of complicated material models.

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This paper presents a simple SDOF formulation for inelastic seismic response analysis of eccentrically loaded steel bridge piers, considering the vertical inertia associated with horizontal ground motion. Modeling of the unsymmetrical hysteretic behavior is verified by pseudodynamic test results. It is shown that influence of vertical inertia force can not be neglected when e/h (e=eccentricity, h=pier height) is relatively large. A parametric study shows that under Level 2 accelerograms, steel bridge piers with intermediate eccentricity (e/h around 0.1-0.2) are susceptible to highest maximum displacement; And eccentricity definitely leads to higher residual displacement level than centrally loaded steel bridge piers.

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A high seismic resistance quay wall experienced the 1995 Hyogo-ken nambu earthquake and survived the disaster. To clarify whether high seismic resistance quay walls can survive future earthquakes, a series of two-dimensional effective stress analyses is conducted. The numerical analyses reveal the mechanism why the high seismic resistance quay wall in Kobe Port survived. The numerical results also indicate that it is possible to significantly reduce the residual deformation of quay wall designed with high seismic coefficient if soil improvement against liquefaction is completed.

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This paper proposes a macro-micro analysis for the prediction of a strong motion distribution in a metropolis. The analysis uses the singular perturbation expansion and the bounding media theory, to reduce required numerical computation and to consider. the uncertainty of ground and geological structures. A prototype of the numerical code for the macro-micro analysis is developed, and an actual earthquake is simulated. The comparison with measured data supports the basic validity of the proposed method.

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This paper presents a method for analysis of strain localization problems which is supported by the thermodynamics of irreversible processes. Stability and bifurcation criteria and a generalized localization analysis method are discussed at the level of structural mechanics. A one dimensional cracking model is examined as a simple example of cracking localization phenomena to show the framework of our method. The method is applied to a practical example of cracking localization in a concrete beam during a bending test. From the results, the importance of the method presented in this paper for a quasi-static strain localization phenomenon in a structure is clarified.

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Influence of load interaction on fatigue behavior of highway bridge components under service loading condition is to be clarified for better understanding of variable amplitude fatigue. Fatigue crack growth analyses considering crack closure effect are carried out on non-load-carrying cruciform joints under periodic overload (POL), variable amplitude block loading (BL) and variable amplitude (VA) loading. The analytical results are compared with those of the tests carried out in the past. Crack closure effect exists in most cases, and load interaction effect is significant under POL and BL. However, load interaction effect is insignificant under VA loading.

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Possibility of rationalization of steel bridges by the use of high strength steel was investigatedd by design simulation based on limit state design method (Load and Resistance Factor design). Design target bridges are 3 kinds of composite continuous I girder bridge having standard span and width in Japan. Minimum weight sections were designed considering strength limit state (under service traffic and during construction), service limit state, fatigue and fracture limit state. As a result, it is confirmed that a section is decided by different limit state for each steel material. In particular, fatigue limit state has an considerable influence on design of high strength steel bridge.

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Hierarchical finite element method is presented for the local stress analysis of thin-walled structures. In the local stress analysis, the zooming technique is used for the substructures in the h-version finite element method, while the over-all structure is analyzed and highly accurate local stresses can be calculated simultaneously by the proposed method. The singular elements are used to prevent the deterioration of convergence of the solution when concentrated forces are applied and stress concentration is received, and transition elements can be improve on the efficiency of the numerical calculation. The adaptability of this method in regard to analyze local stress of thin-walled structures is demonstrated by several examples, and local stress analysis of thin-walled portal-frame and steel deck bridge with trapezoidal ribs are shown.

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By narrowing the box girder width, it is expected that overall costs will effectively be reduced. Moreover, by increasing slab thickness, it is possible to omit stringers in addition to decrease the box girder width. Thus box girder fabrication productivity and bridge durability are greatly improved. If torsional rigidity of the box girder is decreased and the floor slabs became thicker, the amount of required cross-beams can be also reduced.
This paper is concerned with an analytical study focusing on the following points: (1) the validity of omitting cross-beams in the narrowed box girder bridges and (2) in which MSC-NASTRAN was utilized throughout to conduct 3D finite element analysis.

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Instead of radiographic test, ultrasonic test has been applied to nondestructive evaluation of butt welded joints. New type of tandem array transducer was developed. By the tandem array transducer, tandem probe test could be carried out without back and forth scanning. Higher detectability could be obtained by tandem probe technique than one probe technique for butt welded joint specimens. Fundamental investigation of development of new imaging system based on synthetic aperture focusing technique was conducted by the tandem array transducer. Separation of defect echo from bead echoes was also examined in the imaging system. Defect image could be obtained clearly by the new system.

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In the construction of cable-stayed bridges, it is important to adjust the cable tension to the design values. In practice, the adjustment is performed by adding or removing shim plates. In this paper, an attempt is made to apply Fuzzy Logic (FL) and Genetic Algorithm (GA) in order to obtain a practical combination of shim plates. GA is useful for solving the combinatorial problems, because it can deal with discrete design variables and indifferential functions. FL is employed to improve the convergency and to reduce the compution time. Introducing GA, it is possible to obtain the minimal number of cables requiring the adjustment as well as the practical combinations of shim plates. A numerical example is presented to demonstrate the efficiency and applicability of the method developed here.

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In order to control vibrations on a structure having two degrees of freedom system of swaying and twisting vibrations during earthquake, two kinds of Tuned system damper are installed on the structure. In this paper, one method is proposed to determine approximate optimum dynamic parameters of these two damper's (optimum frequency ratio, optimum damping constant, mass ratio of two kinds of damper). The vibration modes of structure are obtained by the method of modal analysis. As for the first vibration, the influence by the second vibration is approximately taken into consideration as rigidity and, as to the second vibration, the first one is approximately taken into consideration as inertia force. And a theoretical method to obtain the values of optimum dynamic parameters of damper's is shown. Also, the applicable limitations of this theory are made clear by numerical calculation.

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In seismic design of cable-stayed bridges, evaluation of damping of structure is important. However, because it is difficult to evaluate damping property theoretically, it is not examined enough on determination of a damping factor. In order to investigate damping property of long-span cable-stayed bridges, the ratio accounting for strain energy of each member, the effect of frictional damping at movable supports and energy dissipation from foundations are examined referring measured data on damping ratio. Influence of setting of damping ratio in seismic response analysis was also examined.

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For years, earthquake ground motion has been observed at 6 stations in Kamakura city, Japan. Among them, two stations of NMD and ONR have been found to show larger vertical motion. Especially at NMD, a maximum acceleration ratio between vertical and horizontal motions is sometimes exceeds 1, with a constant predominant period of about 0.25sec for both vertical and horizontal motions. A 2-D BEM is applied to characterize ground motion at both stations, with a result showing that steep slopes of bed rocks under the surface layers play important but different roles for both cases.

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As seen at Port Island vertical array record during the 1995 Hyogoken-Nambu earthquake, the soil deposits have the upper limit of ground motions because the soil layer can not transfer the shear force larger than its shear strength to upper layers. In order to clarify the relation between the shear strength of soil and upper limit of ground motion, nonlinear analyses are carried out focused on the angle of internal friction. It is shown that upper limit of PGA, JMA seismic intensity scale and SI value are controlled by the angle of internal friction.

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Resonant frequencies of concrete dams are very important property because they influence earthquake responses of concrete dams. For two existing arch dams, resonant frequencies are evaluated from acceleration records during earthquakes at the upper and lower parts of dams. And those are also determined from the results of forced vibration tests and ambient measurements. The relations between resonant frequencies and water levels of the reservoir are presented and it is shown that resonant frequencies at low water range decrease with the reduction of water depth. It is also shown that resonant frequency corresponding to large peak acceleration of dam response is lower than that corresponding to small peak acceleration. It is discussed that these features are attributed to effects such as stress of dam which can affect the contact conditions in the contraction joints.

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After Hyogoken-Nanbu Earthquake in 1995, pounding between the adjacent girders is of major concern from the view point of base isolation. In this paper, an experimental study using the two-dimensional shaking table was performed focusing on the dynamic and impact behavior of the pounding between the adjacent girders. The girder falling was observed due to the pounding between the adjacent girders. The effects of the pounding on the falling girders were examined by the response acceleration of the girders and deformation of the piers. The effects of the shock absorber such as rubber and lead inserted to the bridge restrainer plates in order to decrease impact force were investigated.

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This paper discussed the effect of the integrated sliding bearing system on reduction of earthquake response of bridges. This system consists of the supporting rubber plate to support the main load such as the dead load and the live load, and the slider-buffer system to reduce the earthquake response. The static loading tests showed that more than 230% shear deformation resulted in stiffness hardening phenomenon, and 330% shear deformation destroyed the buffer. The sinusoidal vibration tests and the pendulum weight collision tests showed the friction coefficient of 10-25% in relation to the loading speed. The design procedure of this system was also discussed.

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The purpose of this study is to propose two ways of reducing residual displacements for the high ductility steel bridge piers after severe earthquakes. The first way is to use a seismic isolation bearing. The second way is to fill partially in the pier attached to a seismic isolator with concrete. For this purpose, a new method of pseudodynamic test for steel bridge piers with a seismic isolator is established. Based on the results of the pseudodynamic tests, they are shown that the seismic performance of steel bridge piers with a seismic isolator is evaluated, and a rational range of the natural period to be augmented by the isolator is proposed for practical design.

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Through an experience of damaged bridge structures during Hyogo-ken Nanbu Earthquake, it is required to clarify an elasto-plastic behavior of a bridge pier subjected to two horizontal directional earthquake motions. From this point of view, in this paper, a three dimensional elasto-plastic dynamic response analysis method of beam-column elements is formulated taking into account an yielding of a pier section due to biaxial bending and torsional behavior. An elasto-plastic dynamic response analysis of a single steel bridge pier and an inverted L-shaped steel bridge pier subjected to a set of two horizontal directional earthquake motions recorded during Hyogo-ken Nanbu Earthquake are conducted by employing above analysis method. And a fundamental behavior of a pier subjected a set of two horizontal directional earthquake motions is investigated by comparing the behavior with that under one horizontal directional earthquake motion.

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The present paper is concerned with the strength and ductility evaluation of steel bridge piers subjected to combined the axial force applied eccentrically and in-plane or out-of-plane cyclic lateral loading. In the analysis, a modified two-surface plasticity model is used to trace the inelastic cyclic characteristic of steel. Both the box-sectional and pipe-sectional piers are investigated. Analytical results show that there is a correction of hysteretic curves between the T-shaped and inverted L-shaped piers. Hence, many contributions to the T-shaped columns can be easily extended to the inverted L-shaped or eccentric columns.

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Localized necking is simulated by using three-dimensional elasto-plastic bifurcation analyses. In this study, localized deformations just before the shear fracture of specimens with various width-thickness ratios are analyzed using the J₂-flow hardening theory only. After detecting a bifurcation point precisely and conducting a branch-switching procedure, excellent correlation is demonstrated between the numerical and the experimental results.

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This paper presents a series of uniaxial compressive loading tests on concrete cylinders confined by tie reinforcements in order to develop an unloading and reloading stress-strain model of confined concrete. Variables considered as parameters were the volumetric ratio of tie reinforcement ρ_s, the cylinder strength of concrete σ_c0 and the number of unloading and reloading cycles at the same strain. To predict an unloading and reloading path, the plastic strain ε_pl·n and the stress at the unloading strain σ_ul·n are controlling parameters. These controlling parameters were analyzed based on the test data to propose an empirical relation. The predicted relation provides good agreement with the test data.

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This paper proposes and analyzes an approach to decide the level of acceptable risk for earthquake disasters. The proposed way to decide the level of acceptable risk for national land plannning is estimation of risk of natural desasters such as earthquake, tsunami and flood from the viewpoint of the relation between a death toll and a return period, and decision of upper limit of risk management. Then, the decision of acceptable risk is converted into the requirement for design earthquake of level 2, assuming that the design concept of river facilities is decided the acceptable risk for earthquake disasters. Furthermore, the catalogue of earthquakes are compared with the requirement for design earthquake of level 2 at the chief cirties of Japan.

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The objective of this paper is to indicate the locality of the damage area with respect to centercolumn and to make clear the damage mechanism based on the difference damage between Daikai subway station and Kosokunagata subway station by use of the two step analysis proposed by authors. It is found that the damage degree of center column depends on the location of the subway station. The reason why the damage at Kosokunagata station is less than that at Daikai station is found that the shear deformation at Kousokunagata station is less than that at Daikai station because the stiffness of ground around Kousokunagata station is larger than that around Daikai station.

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Potential usefulness of information entropy is investigated for evaluating engineering systems' safety in terms of reliability, uncertainty and redundancy. The Shannon's information entropy (Khinchin (1957) and Kullback (1959)) can explain of not only a degree of uncertainties involved in systems, but also it can indicate a degree of inherent redundancy of systems. The entropy can gain comprehensively the insight into more than reliability. The system reliability and the redundancy are discussed related with the system configuration, load redistribution after partial damages, material properties and uncertainty in the resistance and loading.
It is clear that the example models are simple prototypes of such systems as highly indeterminate structures and complicated networks of lifelines.

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There is the spatial auto-correlation method (SPACM) for estimation of the phase velocity of surface wave using the array observation of microtremors. It needs to install the seismometers on the circle and at the center. In this paper, a relation between the number of the seismometers and an error in the estimation is made clear. Furthermore, the theoretical applicability of SPACM using two or three seismometers is investigated. As a result, it is found that we can estimate the phase velocity of surface waves having wavelength of more than 3.4 times of the array's radius when three seismometers are arranged at vertices of a right triangle. However, when SPACM are applied to array observation using two seismometers, there is a possibility that the estimation includes a large error. Therefore, a new procedure is proposed to improve the estimation.

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As a first step to evaluate the applicability of the two-dimensional RANS (Reynolds-Averaged Navier-Stokes) simulation to the prediction of unsteady aerodynamic forces for long-span bridges, the k-ω SST turbulence model has been newly implemented in the 2D flow code. The newly developed code was validated using cases for unsteady flowfields around airfoils undergoing large-amplitude motions. It was then applied to compute the unsteady aerodynamic forces for a long-span bridge with shallow hexagonal cross section. Fairly good agreement was obtained between numerical results and experimental data It indicated that the application of the present method to the prediction of unsteady aerodynamic forces for long-span bridges is quite promising.

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