[in Japanese]

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In this paper, the cracking behavior of concrete tunnel lining is simulated by a finite element code with smeared crack model. Based on the experimental observation, numerical simulations are carried out in the following aspects: 1) initial imperfection; 2) concrete tensile strength; 3) fracture energy; 4) load direction; 5) size effect on structural strength and 6) soil mass constrain. The analyses on the items of 1) through 3) treat the basic factors affecting the cracking behavior of tunnel lining. And studies of 4) through 6) can provide a better understanding of tunnel lining response under complicated conditions.

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The presence of possible welding defects needs to be taken into account in order to get rational performance of welded structural member considering its fitness for purpose. Accordingly, it is necessary to identify fatigue performance of welded joint containing various defects. Fatigue performance of butt-welded joint specimens considering five types of defect, which are vary in size and location, is studied in wider fatigue life range. It is observed that the shape, size, and location of the defects considerably affect the fatigue performance of the specimens. Fatigue life prediction by fracture mechanics analysis based on current recommendation is generally conservative in long life region.

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A parallel finite element method based on domain decomposition method is presented for large-scale computation of incompressible Navier-Stokes flow. The finite element computations, carried out using unstructured grids, are based on semi-implicit formulation. The pressure Poisson equation, which consume the most of computational time, is completely parallelized using element-by-element SCG method. The present method is shown to be a useful and powerful tool for the large-scale computation of incompressible Navier-Stokes flow.

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The purpose of the present paper is to investigate dynamic behavior of new types of shear connectors between a corrugated web and a concrete flange in a composite girder. The shear connectors used here are (1) studs welded to the top flange; (2) holes with penetrating reinforcement placed on the top of the corrugated web; (3) the holes with penetrating reinforcement and wire net. The two-point fatigue tests in which the composite girder is placed in a simply supported condition and loaded dynamic manner were conducted using the above three types of shear connectors. Experimental results reveal that, , holes with penetrating reinforcement are more effective than studs in the case of composite girders with corrugated web.

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This paper presents a unified and efficient new optimum design method for nonlinear plane frame structures with box sections. The material nonlinear structural analysis problem is formulated as the total complementary energy minimization problem, and the necessary conditions for analysis problem are derived. Then the primary optimum design problem is reformulated considering both the primary design constraints and the necessary conditions for the analysis problem. In the reformulated optimum design problem the structural behaviors are also dealt with as the design variables. The reformulated optimum design problem is solved efficiently by using the gradient projection method. In the optimization process, the complementary energy sensitivities with respect to primary design variables at each member element is used, however the calculation of behavior sensitivity with respect to primary design variables is not necessary. The rigorousness, efficiency and reliability of the proposed method are demonstrated by comparing the results obtained by the dual method in which the behavior sensitivities are used.

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The 3rd route of Hanshin Expressway was heavily damaged by 1995 Hyogo-Ken Nambu earthquake. Investigation on the damage of the elevated highway in the route revealed that the damage level of the piers with fixed bearing in three-span continuous girder bridges is significantly lower than other piers. In order to understand this fact, the overall behavior of the bridge system including the bearings is analyzed. First, an evaluation method for the seismic capacity of bearings is constructed which encompasses all possible damage modes. The proposed method is shown to agree with the actual damage. Then, the seismic performance of the structural system of the three-span continuous girder bridges is evaluated in both longitudinal and transverse directions. The analysis indicates that most of the observed damage patterns fundamentally reflect the seismic capacity of structural system.

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This paper deals with the creep behavior in steel-concrete double composite continuous box girder bridges. First of all, main characteristics and the outline of a construction procedure for this new type of bridge are described. Next, the relationship between stress and strain in concrete for analyzing the creep behavior and the solutions for creep are presented. Finally, a three spans continuous double composite box girder bridge is selected as the analytical model and its numerical analysis is carried out. As the results, changes of stresses in upper and lower concrete slabs and steel box girder and also deflection of the girder due to creep are made clearly.

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The instantaneous surface-pressure distributions on two-dimensional rectangular cylinders of varying length to ratio, in a smooth uniform flow and in a homogeneous turbulent flow, have been measured and the effects of the free-stream turbulence have been investigated by analyzing such as quantities as the power and co-spectra and the spanwise correlations of the simultaneously measured pressure distributions. When the length to width ratio is small so that the separated flow does not reattach on the side wall, the pressure fluctuations on front surface is influenced by the vortex shedding whether or not there is turbulence in the free stream. When this ratio is larger and the flow reattach, the front-surface pressure does not show periodicity but a negative peak appears on the side wall periodically and propagates downstream.

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The 1995 Hyogoken-Nanbu Earthquake has emerged the necessity of highway system in function as a lifeline even after main shock. Therefore, many research works have been carried out in order to evaluate the response of elevated bridges under severe ground motions. Carried out herein is a shaking table test on scaled elevated bridge model, consisting of three single span elevated bridges. The bridge model was shake in the direction of the bridge axis and the effect of pounding between the adjacent girders on the global response is focused. In addition, the validity of the response analysis available currently is assessed by comparing to the experimental results.

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This paper proposes a sub-objective optimal elite genetic operation strategy for improving the numerical computational efficiency and applies this method to the interactive optimal design of space truss structure. In case that the multi-objective function consists of many sub-objective functions and some of sub-objective functions have a clear relation to the particular design variable, a genetic operation improving directly the sub-objective functions may accelerates the optimal solution searching process. The proposed method can apply to the interactive optimal design of truss structure. The computational efficiency and reliability are discussed by using some truss design problems including an electric power transmission tower design.

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The relative velocity response and the seismic collision velocity between the adjacent bridges were studied. The seismic response analyses were conducted using the 2-degree-of-freedom system. The results showed that the structure of the longer natural period took the dominant part on the relative velocity response between the adjacent structures. The damping effect of the friction or the viscous damping system between the structures also was evaluated using the relative velocity response spectra.
The effect of pounding was evaluated using the collision velocity spectra considering the natural period ratio of the adjacent structures. The collision velocity spectra showed that the collision velocity increased as the relative response limitating displacement increased.

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Satellite and airborne remote sensing is expected to provide effective spatial information on earthquake-induced damage. Several satellites observed Kobe area before and after the Kobe earthquake. Since a part of the damage survey results of this earthquake is maintained as GIS data, a quantitative analysis of the surface changes in the damaged area is possible. Spectral characteristics of the damaged area were investigated using Landsat and SPOT optical images taken before and after the earthquake, for examining the possibility of extracting the earthquake damage distribution by satellite remote sensing. The damage distribution extracted by the discriminant analysis of the spectral characteristics agreed with the results of the field survey.

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Simplified design methods for obtaining the maximum strain in pipelines crossing active faults proposed by Newmark, Kennedy and Wang have not considered the section deformation. In this study, a new simplified method is developed for obtaining the maximum strain in steel pipes crossing fault considering material and geometry nonlinearity of pipe section. It is assumed that the pipe will bend near the fault and the geometry of pipe in longitudinal direction will change according to a bent deformation. On the other hand, the relation between maximum strain and bent angle has been obtained by using a beam-shell hybrid FEM for different pipe-fault conditions. The developed design method can calculate the maximum strain considering the bending point of the pipe near the fault

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The numerical simulation code was developed to simulate the aero-elastic phenomena of three-dimensional structures. To validate the accuracy of the code, the fluid-structure interactive simulations were carried out about circular tower elastic model. The results of the simulation were good agreement with experimental data as for the occurrence wind speed of the vortex-induced vibration that was caused by karman vortices. But the vortex-induced vibration at a high wind speed did not occurre by the simulation, so further study is neccesary about grid system and FEM modeling.

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A hierarchical cable element is presented for the 3-D finite displacement analysis of cable structures. The element is a high order isoparametric element of p-version and highly accurate solutions could be obtained with one element for a extremely slackened cable. Moreover, an adaptive technique is proposed to improve on the efficiency of the numerical calculation of cable structures. The convergency and stability in the computation are demonstrated by several examples.

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In the design of cable-stayed bridges in our country, the stress and stability verifications are generally made based on the specification of highway bridge (JSHB). However, the validity of using the verification formula of the specification of JSHB for the complicated structure such as the cable-stayed bridge has not been made clear. Therefore, the development of the simple and precise method for calculating the ultimate strength of the cable-stayed bridge and moreover the establishment of the safety verification method are wanted. In this paper, for the calculation of the ultimate strength of long span cable-stayed bridges, the effectiveness of the E_f method is made clear through comparison with the result obtained from the E_f method and that from the elasto-plastic finite displacement analysis. Moreover, by comparing a newly proposed verification formula with the verification formula of the specification of highway bridge, the effectivity of the propose formula is presented.

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During the Hyogo-ken nanbu earthquake, strong pulse with maximum acceleration of over 800cm/s² and with maximum velocity of over 100cm/s was recorded at JMA Kobe. As the recorded waveform is very simple, numerical simulation of acceleration pulse will be possible using source model. In this study, a new two dimensional slip function model is proposed which expresses slip process of asperity referring already published rupture process estimated by inversion of strong motion records. In the former half of this paper, formulation of the 2-D slip function and one case study are shown. In the latter half, numerical simulation of pulse record at JMA Kobe during the Hyogo-ken nanbu earthquake is shown and applicability of the proposed model is discussed.

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The continuous composite girders are mainly used for bridges. Cracking of concrete slab plays an important role near the intermediate supports where the negative bending moment occurs. Crack width is calculated by using strain of reinforcement and crack interval. In EUROCODE 4, the shaft tension model is developed for the analysis of negative bending behavior, and the crack width is calculated from the model. In this study, a new calculation technique for the estimation of crack width is proposed with the help of crack interval given by Japanese specification and strain of reinforcement determined by EC 4. The proposed technique is validated by comparison with experiments of girders with the negative bending moment.

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For the Kaneihara pumped storage power station of Kansai Electric Power Co., we evaluate a Level-2 earthquake motion for the seismic design of dam using seismograms recorded at the site.
In most projects of infrastructure constmcction, strong motion observation is usually started for their maintenance after their construction is completed, and a seismograph is rarely installed before their design. The method of Irikura & Kamae (1994), one of the empirical Green's function methods, is selected to estimate earthquake ground motions. The method is one of the most accurate techniques, but it is rarely applicable to practical design because of the lack of ground motion records at the construction site.
In this project, a seismograph has been installed at the site before a process of design. We estimate strong motions which would be generated by Yanagase fault using ground motion datum observed by the seismograph. The simulated strong ground motions include the effect of the source process, the amplification at the site and the characteristics of propagation path between them properly. The Level-2 earthquake motion for seismic design of the rock-fill dam is evaluated based on the simulation.

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About 100 repair cases of failed steel bridges owing to fatigue are summarized into a data base. Each case is categorized by failure cause and repair method. This data base is available on the internet, so that anybody can refer to the information. This paper introduces the system of the database and how to utilize it. Further, repair methods are evaluated by analyzing all the cases, which are included in this database.

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An array observation system of earthquake motions, named Small-Titan, was installed in Sendai City, Japan in 1998. It consists of 20 observation stations and one control center. The average station-to-station distance is about 4km and each station was installed at various kinds of soils to effectively detect local site conditions. Since its completion, the observation system has obtained some 100 records. Especially, it observed a maximum acceleration of about 455 gal during a typical near-distance earthquake with a magnitude of 5. This paper outlines the observation system and discusses the effects of source and local site conditions found in the observed records.

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Corrosion is the major cause of deterioration of steel bridges, and corrosion damages seriously affect on the durability of steel bridges. So, corrosion damage must be carefully evaluated. At, present, however, there are no established means of evaluating the extent and effects of bridge corrosion. In this study, first of all, corrosion characteristics in steel bridge members are discussed. Amount of corrosion informations concerned with the types of corrosion found, locations of corrosion on bridge elements, and environmental effects on the structure in existing steel bridges were gathered and estimated. From this investigation, we are trying to make, so to says, corrosion maps of each types of steel bridges. Secondly, non-destructive techniques of adequate corrosion inspection are described.

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During the service of steel bridges, typical fatigue cracks have been found at the toes and the roots of welded joints considered as load-carrying fillet welded joints. It is well known that the fatigue failure modes are influenced by three fundamental factors: the weld size, the weld penetration and the plate thickness. However, since their effects on fatigue failure mode have not been clarified, no evaluation method has been established. In this study, parametric fatigue life analyses were carried out on the fillet welded cruciform joints in order to quantitatively clarify the influences on the fatigue failure modes. According to the analytical results, a quantitative method for evaluating the fatigue failure modes was proposed in consideration of the weld size, the weld penetration and the plate thickness.

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A girder-to-girder connecting cable to prevent a girder from unseating is important device to prepare for huge displacement response due to severe earthquake. This paper studied the demand capacity of the connecting cable for the worst situation that the girder was falling off from the pier top. First, the equation of motion for a free falling of a simple girder was derived. Then, the subsequent shock absorbing process with a spring, a viscous damping device and a hysteretic damping device was considered. The numerical simulations showed an example of the maximum acting force to the connecting cable and demand displacement for its operation.

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