[in Japanese]

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The structural performances of composite tubular K-joint leading to real truss bridge construction of high speed Shinkansen train are presented. The experimental studies on improving the fatigue performance of welded steel tubular joints by upgrading the structural joint details and improving the weld toe profiles were carried out on ten tubular K-joints under repeated constant amplitude load. The behaviour of all joints were examined through the analyses and the tests. The results suggest that concrete filled tubular joints are able to improve the fatigue strength substantially compared to unfilled joint.

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Seismic hazard and microzoning of the Philippines are presented. Seismic hazard analysis of the Philippines on rock-surface level is done to all land areas of the country. The analysis includes both the historical earthquake occurrences and active fault data. Ground motion amplification corrections based on surface geology is determined based on the representative soil softness index of each geology type. The resulting amplification corrections are applied to the rock-surface seismic hazard of the Philippines. A significant increase of seismic hazard by applying the amplification corrections is shown for the city of Manila.

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The following factors are identified to have a critical effect on seismic risk in Greece. First, exposure to seismic hazard is strongly non-uniform, with over half of the country's 10 million population-and accordingly most of the industry and infrastructure-concentrated in only two major urban conglomerates. In addition, many of the potentially damaging earthquakes occur in sparsely populated areas or have their foci under the sea. Last, the enforcement and upgrading of seismic codes since 1959, in combination with a generally good quality of construction materials and workmanship, contribute to a relatively reduced vulnerability of structures.

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The effective length concept has been widely accepted in the design of framed structures. An excessive accuracy is not to be expected from its origin apart from structural analysis, but there still remain certain cases where its estimation is far conservative beyond reality. The practice for a rectangular frame is set up differently depending upon whether braced or unbraced. Literally, the effective length has been designated as an axial strength of individual members. In this study, an inadequacy is found in those conventional practices, and an alternative manner is suggested to deal with the structural buckling of a rectangular frame.

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Ultimate strength of composite slab is strongly influenced by horizontal connection force between steel and concrete. Degrees of composite action in partial composite slab is expressed by a parameter given by horizontal connection force deviled by concrete force under full composite slab. Ultimate flexure strength of partial composite slab is calculated by this parameter. The horizontal connection force is composed of several kinds of force such as friction force, stud zibel force. Contribution of these components are examined by loading tests with real size specimens with and without stud on steel decks. Ultimate load capacity of partial composite slab with profiled sheeting can be obtained from the partial composite model. Results of calculation of this model are verified by nonlinear fiber stress model which uses measured strain distribution of slab specimens. Horizontal connection force obtained from the nonlinear fiber model coincide well with that of partial composite model.

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This report proposes a practical method to calculate the structural deformation of buried pipelines under lateral displacement in the liquefied ground. Based on many cases of FEM analysis using shell/beam hybrid model, plastic hinge model is adopted to deal with the inelastic behavior of pipelines. Also, formula to estimate plastic moment of curved pipes, are proposed. The relationship between plastic hinge model and FEM is shown in some cases, these are nearly same. This proposed method is useful in practical design formula to calculate large deformation of pipelines, such as the deflection angle of the bend comer.

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The aims of this paper is to verify the efficacy of Joint Damper System (J. D. S.), which is one of the structural control method that can reduce dynamic responses of multiple structures by connecting these structures with energy absorption devices. For this purpose, full-scale structural vibration control experiment with using variable damper device is executed. This device is controlled so that it works like an idealized viscous damper device.
As a result, validity of the analytical solutions of the optimal joint damper coefficients is confirmed. Also, it is shown that control effects of Joint Damper System differ greatly in accordance with the characteristics of earthquake and structural parameters.

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A dynamic centrifuge test and FEM analysis were carried out to investigate a seismic behavior of buried pipeline due to lateral flows caused by ground liquefaction. The model of the centrifuge test, which was performed under the centrifugal acceleration of 30g, consisted of a caisson type quay wall, upper unliquefable, lower liquefable layer and high-pressure gas tube with the outer diameter of 600mm in prototype scale including a 90 degree bent part. Lateral flow induced by the deformation of the quay wall made the model pipe a large deformation up to plastic strain level. Furthermore, the applicability of analysis by FEM shell model was verified to simulate the large deformation of pipe model.

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To elucidate the dynamic behavior of rockfall prevention structure by impact of a rock fall, a numerical analysis method is developed combining Distinct Element Method and Finite Element Method. The verification of this method has been done by comparison with the experimental results. The relations between falling height, mass of rock, duration of impact and eigen period of structure have become clear on the basis of numerical results under various impact conditions by rock falls. The characteristics and the ratio of finally transmitted energy to the structure also have become clear. Furthermore, a relatively simple method to estimate the ratio of transmitted energy to the rock fall preventive structure and the impact load have been suggested.

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To increase the load-capacity of the existing plate girder bridge, there are two ways of strengthening method, by using cover plate and by using prestressed external tendon. As for these methods, the strengthened effect to load-capacity has been confirmed. However the endurance effect has not been confirmed. Especially, the dynamic behavior due to moving vehicle of the member with secondary stress that fails under fatigue is not clearly understood. Comparing of experiment and analytical primary and secondary stress due to moving vehicles in the existing plate girder bridge strengthened by prestressed external tendon confirmed the validity of this study. Moreover, this study evaluated strengthening effect of endurance due to fatigue failures using analytical results.

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The load-carrying capacity of corroded steel-bridges may be reduced due to cross sectional area reduction, surface non-uniformity, and unexpected stress concentration. Unfortunately, there is still no suitable means to evaluate their remaining load-carrying capacity. In this study, we quantitatively evaluated bearing capacities of girder ends extracted from replaced corroded steel girder bridge by experimental and finite element analytical method. As a consequence, it was found that the remaining bearing capacities (maximum loads) decreased as corrosion rates increased but were still higher than the design load, there is a close relationship between remaining bearing capacity and minimum of residual cross sectional areas throughout the height of the fictitious column at the girder end.

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The security of information owned by individuals against large earthquakes will be important as the number of personal computers and networks is rapidly increasing. Since the system halting can be done in micro-seconds, it is wise to give an alert for coming S-wave, by analyzing P-wave characteristics which is routinely measured by many seismographs. In this paper, the acceleration rate is used as a measure of the P-wave characteristics, since it can give an earliest warning. The model analysis and the data analysis are carried out to verify the validity and to examine the usefulness of this measure, and the results support the advantage of the accreration rate.

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In this study, the measurement system for continua by image processing technique is developed. At first, the correlation method for Eulerian coordinate system is updated to trace the large deformation field in Lagragian coordinate more accurately by considering the deformation of the template. Then, the method to correct the measured field by using the volume constraint condition is proposed. Finally, to demonstrate the effectiveness of the proposed system, the system is applied to the measurement of the deformation field of the devices that deforms largely.

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The applicability on the dynamic verification method for seismic design is verified. In this method, the ultimate states of structures are decided by comparing strain time history of the segment considered as the collapse point with the ultimate strain based on structural properties. The strain time history is obtained in dynamic response analysis using fiber element model, not using shell element models. The objective structures are steel bridge piers in this paper.
Firstly, analysis results with this verification method are compared with quasi-static experiment results simulated seismic response. Secondly the results obtained using this proposed method are compared with results using shell element models on dynamic response analysis. These results tell us the validity of this proposed verification method.

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This paper proposes a rigorous, reliable and efficient minimum cost design method for substructures of seismic-isolation bridge systems considering initial construction cost and repair cost caused by a huge earthquake. The special characteristic values for nonlinear dynamic hysteresis of seismic-isolation bearings, piers and pile foundations are dealt with as the design variables. The relationships between least initial construction costs of rubber shoe, RC pier, RC pile foundation and the corresponding design variables are introduced by using suboptimization processes. The repair cost of each segment is evaluated by considering damage factor, repair cost factor and least initial construction cost of the segment. The estimation formula of maximum horizontal response displacement at each segment is introduced efficiently as the function of design variables by the Experimental Design Method. The cost minimization problems of bridge systems are solved quite efficiently by using a convex approximation concept and the Lagrangian Dual Method. The effects of the horizontal displacement constraints on the minimum cost of bridge systems are also investigated.

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Modeling of High Damping Rubber materials (HDR) is studied. At first, the material tests required for modeling are systematically conducted. Based on the results of the material tests, a constitutive model of HDR is proposed. This model consists of elasto-plastic body and hyper-elastic body in parallel. The simulations by the model are found to be in good agreement with the experimental results. Then, a hybrid analysis method is proposed, in which strain field of laminated rubber bearings measured by image processing is combined with the numerical analysis to confirm the applicability of the proposed model to the bearing. In addition, by this hybrid analysis method, the bulk moduli of rubber materials used in the bearings are computed.

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Because the phase spectrum of an earthquake motion controls its nonstationary characteristics we take into account the spacial correlation of phase characteristics to interpolate the earthquake motions at unobserved points using observed earthquake motions. The regression equation to simulate phase spectra is derived as a function of rupture length and epicentral distance using the observed earthquake motions during the Chi-Chi earthquake (1999). Using a sample phase spectrum and the concept of the Kalman Filtering, we developed a method to simulate earthquake motions at unobserved points.

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Effects of dynamic interaction to the soil-structure system have been discussed by many researchers and aseismic design procedures taking into account the interaction effects are strongly expected. In this study, we try to incorporate the effects of the dynamic soil-structure interaction can be adapted briefly in the simple Sway-Rocking model. The procedure to evaluate the sway and rocking springs, however, has not been well established yet. We here propose the method to evaluate the soil springs of the soil-pile interaction by using pushover analysis. The results are compared with those of the finite element analysis and both are in good agreement.

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This paper has dealt with the train-induced vibrations through the track and ground interaction under a moving train. The solution method is to apply the 2.5 dimensional finite element method (2.5-D FEM). The X-2000 of the Swedish National Railway was chosen for the model for analysis; since the measurement data are available for comparison besides a unique response features were observed. At a soft ground, the high-speed operation led the so-called transeismic range that resulted in significantly large vibrations of the track and nearby ground. With the aid of computer simulation, the authors interpret the mechanism for vibration generation and propagation that facilitate the prediction and mitigation when the WIB (Wave Impeding Barrier) measures are taken at the site.

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Unseating of girders due to surface earthquake fault was observed in many bridges in 1999 Chi-Chi Earthquake, Taiwan, which has not been considered in current seismic design of bridges. In this research, unseating behavior of bridges is analyzed based on the observed data at Chi-Chi Earthquake, and countermeasures are considered. First, 6 degree of freedom dynamic response model for bridge superstructures is constructed, and is shown to agree with the actual damage. The damage is found to be primarily caused by static fault displacement. Several countermeasures of unseating are proposed and their effects are examined with the same analysis model.

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This paper presents the shear strain transmitting characteristics from the surrounding ground to the underground structure with rectangular cross section. In the current seismic design methods proposed for the underground structure, only the horizontal deformation is considered to evaluate the seismic shear deformation. This paper shows that considering the horizontal and vertical deformation and the rotation of the structure in the ground, the shear strain ratio depends only on the shear stiffness ratio between the ground and the structure, not on the other parameters including the cross section and the location in the ground. Finally, a simplified analytical method of the seismic deformation of the underground structure is proposed based on the shear strain transmitting characteristics.

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As a new RC structure with high seismic performance, the Unbonded Bar Reinforcement Concrete (UBRC) structure is proposed. Installing unbonded high strength bars into a RC pier, the post-yield stiffness can be easily increased and controlled. This structure can reduce not only maximum displacement response but also the residual displacement by the combination of the elastic bar's action. And the elastic bars can generate stable inelastic hysteresis loops. From the results of cyclic and pseudo dynamic loading tests, it is verified that the UBRC structure has high seismic performance. And consequently the UBRC structures also have the rational advantage for the two-level seismic design. From the trial design of the railway structure, it is found that the UBRC structure can reduce the amount of sectional area and reinforcement, but can be satisfied with the required performance of both of L1 and L2 earthquakes.

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Studied herein is the effect of the girder-to-girder connector on the overall response of the elevated bridges subjected to the strong ground motions. First of all, the seismic response of elevated bridges considering the girder-to-girder connector is assessed based on the analysis by the spring-mass-dashpot model of structures. Secondly, the analytical results in the seismic response of the superstructure by varying the stiffness and the strength of the girder-to-girder connector are compared each other. It is concluded from simulations that when the girder-to-girder connector is used, the response of the superstructure can be reduced; however, little difference in the maximum displacement response of piers is observed. It is also concluded that the maximum acceleration acting on the connector; that is, the impulsive force acting on the connector can be reduced when the stiffness of the connector is reduced by the rubber shock absorber.

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The present study examines experimentally and analytically the fatigue strength improvement of out-of-plane gusset welded joint by additional welding using low temperature transformation welding materials. The measurement and FEM analysis indicate that high compressive residual stress can be introduced only in the vicinity of the additional weld toe. The stress concentration can be reduced because the weld bead becomes to have un-equal leg length but the reduction is not large. By this method, fatigue strength can be largely improved, 0 to 3 JSSC classes or more but the effectiveness depends on the applied stress ranges. This fatigue strength improvement is also obtained for the web-gusset joints of the large-scale girder specimens.

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This paper proposes a new neural network system that differentiates the multi-pattern mixed data into multiple pattern fitting functions, and its application for structural monitoring system to detect the change of structural characteristics. All parameters dominating cause of output monitoring signals are not necessarily monitored in real monitoring system. In such case, the relationship between input and output monitoring data are seemed to be relating to multiple functions controlled by hidden parameter. The proposed neural network systems can differentiate those data into multiple pattern-fitting functions. This network system can detect the appearance of new pattern of input-output relationship of structural monitoring data caused by a damage or deterioration.

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During the 2000 Western Tottori-prefecture earthquake, strong motion records at Kasho Dam showed as much as 2051gal at the dam crest and 531gal at the dam base, respectively. Integration of the accelerogram resulted in permanent displacement of 28cm to the north, 7cm to the west and uplift of 5cm. The dam is a 46m-high concrete gravity dam, and survived the earthquake without damage to the dam body. However, the reservoir water level showed sudden drop of 6cm followed by damped free vibration, Numerical simulation has proved that these ground displacement and water level change are direct influence of the seismic faulting underlying the dam site.

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When a momentary pressure pulsation takes place at a turbine, and its frequency coincides with the natural frequency of a steel penstock, there occurs resonance thus resulting in a noticeable vibration. Lately, there is a tendency to increase the rotation frequency of turbines, on the other hand, the plate thickness of penstocks becomes thiner compared with before. As a result of the tendency, the oval vibration was found at some hydraulic power stations. Considering that rules on prevention of vibration are not necessarily corresponding to the oval vibration, we gathered information about existing penstocks constructed within the last 30 years. Based on the information, formulae to calculate the natural frequencies were proposed including the case with circumferential stiffener rings.

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Many fatigue cracks were found in beam-to-column connections in steel bridge frame piers in Metropolitan high-ways. In this study, the investigations on fatigue performance of beam-to-column connections with box sections were conducted by experiments and FEM analysis. From the results, it was pointed out that in fatigue design of the connections, it is necessary to consider the high stress concentration occurred at the edges of flange plates. And it came to be clear that in welded joints at the connections, unwelded zones could be included due to partial penetration, and that they could cause the low fatigue strength of the connections. For that reason, full penetration welding should be applied to avoid the introduction of unwelded zones.

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This paper presents a fundamental study of structural health monitoring technique called the piezo-impedance method, which utilize an electromechanical property of piezoceramics. For a thin beam with tensile force, an analytical model of the piezo-impedance method is developed on the basis of the wave propagation theory. Also, a tensile force identification method in a thin beam is proposed. An experiment is performed with small test pieces of beam to investigate a validity of the proposed method and it is found that analytical results are in good agreement with experimental measurement results and absolute value of the tensile force is identified with accuracy. By using the proposed method, it is possible to identify tensile force in a beam from only one measurement.

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The present study aims at presenting the earthquake resistant evaluation method for pile-supported wharves. For the purpose, frequency characteristic of pile-supported wharves was evaluated with strong-motion array observation and microtremor observation at Yokohama Port and Kawasaki Port. Natural periods and seismic coefficients of the wharves obtained with observation were compared with those assumed with present design code. Moreover, two-dimensional earthquake response analyses taking into account the effect by the access bridge between the superstructure of the wharf and the retaining wall were conducted. Necessity for modeling the access bridge was verified and earthquake resistant evaluation method was proposed.

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The objective of this paper is to propose the method for estimating the nonlinear response of the structure with SDOF. The characteristics of the method is as follows: Maximum index based on kinetic energy of earthqueke ground motion is used as the characteristics of earthquake ground motion to represent the non-linear response of structure. The normarized energy index is related with normarized potential energy of structure response. The method to estimate maximum ductility factor by use of frequency characteristics of maximum index is proposed by developing the relationship mantioned second characteristics. The applicability was confirmed by the comparison with the maximum ductility factor calculated by non-linear seismic response of structure with SDOF.

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The characteristics of collapsed buildings were examined by image processing of aerial television images taken after the 1995 Hyogoken-Nanbu earthquake. Areas with building damage were defined by color indices and edge elements of an original image, and by edge information and statistical textures derived from the co-occurrence matrix of edge intensity. In the latter case not using color indices, the estimated results were in good agreement with the actual distribution of collapsed buildings, and it was relatively easy to apply the threshold values to an adjacent image. As the edge information can be derived from a gray scale image as well as brightness, the proposed method is applicable to the high-resolution panchromatic satellite imagery with one-meter spatial resolution.

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Recent design codes for continuous composite girder bridges allow tensile cracking in a concrete slab near intermediate supports. To ensure durability of the concrete slab, introduced crack width has to be limited within an allowable limit, and accordingly it becomes important to predict crack width under a service load. In this paper, crack width evaluation methods for steel-concrete composite girder under negative bending moment are compared to investigate differences in those mechanical background and evaluated results. Inconsistency in application of conventional methods is pointed out.

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High Strength bolted tensile joints are classified into both tension type joints and friction type joints because of the existence of compression force between two tee flange plates due to high bolt pre-stress force. That is, high strength bolted tensile joints subjected to shear force also work as the friction type joint. Most of the past studies concerning this type joint have been mainly investigated on the mechanical behavior subjected to only tensile force. Therefore, in order to apply this type of joints to actual connections of steel bridge members, the behavior under various combinations of axial force, bending moment and shearing force must be investigated. In this study, an experiment has been carried out for the specimens modeled as connections of box members subjected to tensile force, bending moment and shear force. And the effect of tensile force and shear force has been discussed.

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The objective of this study is to assess the applicability of carbon fiber reinforced polymers (CFRP) to a structural member. Three basic tests to assess tensile, compressive, and bending strength are carried out on the hollow rectangular CFRP structural members. In this series of experiments, 5 types of specimens, which had different thickness and direction of carbon fibers are tested. As a result, it is found that the elastic modules and the strength in compression were less than those in tension, so that the proper stiffening may be necessary for thin CFRP elements in compression. Furthermore, it is also obtained that the tensile strength has tendency to decrease as the number of lamina increases. For the further research, the development of the production process with cost efficiency, quality evaluation method, and design method must be made in order to promote CFRP materials in structural engineering.

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It is well known that the notch toughness of steel becomes low when it suffers plastic deformation. This fact has been obtained by many Charpy impact tests in which the specimens have plastic deformation in rolling direction of steel plate and the side notches are introduced in the direction perpendicular to the rolling direction. In this study, the influences of following factors on the notch toughness of structural steel SM490Y with plastic deformation of 0 to 10% are examined though the Charpy impact tests. These factors are direction of plastic deformation, notch direction and notch angle.

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To estimate the subsurface structures of Tottori plain, a microtremor observations were carried out. This area was severely damaged by the 1943 Tottori earthquake (M7.2), with damage concentrated in the alluvial plain. Microtremors were observed using seismic arrays (7 sites) and a 3-component single site observation (413 points). The observed data were analyzed using the spatial auto correlation (SPAC) method or the horizontal-to-vertical spectral ratio (H/V). S-wave velocity structures to the depth of about 1km were estimated by the analysis of array observational records. The distribution of the peak period of H/V was derived by the analysis of single site observational records.

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Spatial variation of Q_S-value can be estimated using double spectral ratio of strong motion records. Q_S-value estimated at the central Aichi Prefecture is high relatively to that in the eastern and western parts of Aichi Prefecture. Median Tectonic Line passes through the eastern part and an active fault zone exists in the western part, which is supposed to be the cause of the low Q_S. The spatial variation of Q_S-value may be closely related to the heterogeneity of the crustal structure such as asperity distribution in the crust.

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