Due to severe damage of bridges caused by the Hyogo-ken Nanbu Earthquake in 1995, very high seismic force is adopted in the seismic bridge design specification revised in 1996. Compared to the inelastic design methods, base isolation design and structural control design which reduce structural response with innovative devices have strong merit in vibration theory and in construction cost. In this paper, the recent development of the devices and their application to long span bridges are reviewed, and in addition the new negative stiffness damper under development is introduced.

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The paper describes an impact response analysis of the simply supported elastic circular cylindrical shells composed of two bonded isotropic layers. Exact analysis is developed using the method of eigenfunction expansion based on the three-dimensional theory of elastodynamics. The axisymmetrical compressive load is suddenly applied radially inward and outward on the surface of the shell. Numerical calculations are made for the steel-concrete cylindrical shells, and the propagation of stress waves in the shells are shown graphically. The present results can be served as a reference to approximate solutions using numerical approaches such as FEM.

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This paper presents the three-dimensional (3-D) stress analysis of four edges simply supported thick plates resting on elastic foundations. The thick plate is subjected to a body force as dead weight and a surface force as fully or partially distributed uniform load. The analysis is based on the theory of elasticity, and the elastic foundation is described by the Winkler model. In this paper, an analytical solution is mathematically derived by using the double Fourier series expansions. The convergence of derived series solution is demonstrated by several examples. The effects of thickness-to-length ratio, non-dimensional foundation parameter and transverse loading condition on the displacements and stresses of thick plates resting on elastic foundations are investigated.

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The welding is a technique for connecting two materials by partially heating and melting. Therefore, the welding deformation is inevitably caused by thermal expansion and shrinkage non-uniformly caused. It is important for the quality control of the welding member to understand the deformation and the strain that arises on the surface of the steel member while welding. In this study, the deformation and the strain behavior caused on the surface of the steel member in welding and cooling process were verified by digital image correlation method (DICM) and 3D thermal- elastic-plastic FE analysis.

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Equal angle steel members are widely used and generally bolted to other members. Then, the axial compression load eccentrically subjected to the member greatly influences on the ultimate strength and post-buckling behavior of the member. Also member buckling will influence on the ultimate strength of trussed structures, which are assemblage of the angle members. In this paper, transmission line tower consisting of equal angle steels bolted is focused on and the ultimate strength of it and the modeling method of the component members for non-linear analysis are discussed by focusing on decrease of the load carrying capacity due to the eccentric loading to the members. Through comparisons between analytical and experimental results of angle members, a plane trussed structure and an actual transmission tower, an adequate modeling method of the member is verified. Also investigated is Sensitivity Index of the member which represents the decrease ratio of the ultimate strength due to the absence of member.

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New loading method is proposed to evaluate an ultimate strength of radial gate arm during gate operation experimentally. In the proposed method, one wire rope and some pully blocks are attached among an experimental model of radial gate strut arms. Water pressure load is simulated by suspending a heavy mass on the wire rope. On the other hand, another wire rope is attached along an arc-like skinplate of the gate model. Gate opening is simulated by pulling the wire along the skinplate. Feasibility of the proposed method is confirmed through the experiment.

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The Japanese design specifications for highway bridges are now under revision. The revision aims mainly at implementing recent advancement of bridge engineering and updating/correcting design rules and equations if necessary. In the volume for steel bridges, several topics have been picked up and worked out. One of the issues is the design of a member subjected to bending moment. Specifically, the evaluation for P-δ effect, the formula for the equivalent bending moment and the way to deal with non-prismatic members are investigated in this paper. As a result, a new equation for P-δ effect is proposed, the validity of the formula for the equivalent bending moment is confirmed and a method for the design of non-prismatic members is tried out.

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In reducing and in preventing the damage to bridge structures, knocking-off members or devices are adoptable. Then, it is important to understand their brittle fractures and to obtain their controlled and stable breaking loads. In this paper, high strength bolts inserted a slit around their shanks are dealt with among the knocking-off members and their breaking characteristics are investigated through tensile and shear break tests. It is concluded that the height and depth of the slit is not sensitive to the shear breaking load of the slitted bolts and the breaking load is approximately figured out by using the cross sectional area of the slitted part and tensile strength of the bolt material.

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Recently, it is strongly required to give concrete structures a longer life by means of the proper control of maintenance. As for the control, it is necessary to evaluate the soundness and quality of concrete structures. Among nondestructive tests for the evaluation, an ultrasonic wave method has high detection accuracy for defects in a material. In this study, numerical analyses are conducted with considering the degradation and cracking occurred by an alkali-silica reaction to check the applicability of an ultrasonic wave method, above all a surface method. It is turned out that the amplitude of the wave decreases through deteriorated area around an aggregate, and that a reflective wave across a crack is visible in a response displacement at a receiver. In conclusion, the possibility that the surface method seizes the defects in concrete structures is shown.

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This paper presents an application of the distinct element method with assembled element on shear resistance evaluation technique of filled boulders in simple shear steel frame, as a fundamental study of estimation method of the shear resistance of filled materials in the steel made Sabo structures. The simple shear test carried out in advance is modeled by using 3-D distinct element method to evaluate the shear resistance and analyzed its mechanism of the filled gravels. The relationship between shear resistance and the displacement is analyzed, and compared with the experimental one. The effect on ruggedness of assembled element in the simple shear resistance is discussed.

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In this study, it was tried to solve two subjects. One is about how the combination of the optimal attribute is extracted out of a huge decision rule. Another is about how many are appropriate to the number of attributes with which man can recognize a form, color, etc. The decision rule analysis method using the column score calculated from CI value of a decision rule was applied. Comparison with the analysis result by the conventional qualification theory was performed. And the combination of an attribute and an attribute which has had on evaluation is examined. Moreover, comparison at the time of changing the number of attributes from 2 to 9 is performed using a decision rule analysis method.

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In this study, a fundamental study on game theory (Nash bargaining solution) approach to the bridge maintenance planning is presented. When a bridge is repaired at appropriate time, the gain of the bridge is maximized. Annual budget forces the repair schedule to be slid, so balanced modification of the repair planning is searched. Each bridge is considered as a player, and the bridge group gain is maximized at the same time as pursuing the maximization of an individual gain by adapting Nash bargaining solution with proper utility function. Also, priority of the repair is shown by using properly the concaved utility function and the convex utility function.

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This paper presents an evaluation method for seismic reliability of important earth structures subjected to earthquakes. The method is based on design basis analysis. First, ground motion index that is strongly correlated with damage or response of the specific structure, is selected. The ultimate strength in terms of selected ground motion index is then evaluated. Next, variation of soil properties is taken into account for the evaluation of seismic stability of the structures. The variation of the safety factor is evaluated and then the variation is converted into the variation of the specific ground motion index. Finally, the fragility curve is developed and then the annual probability of failure is evaluated combined with seismic hazard curve. The fragility curves and annual probability of failures are verified with Monte Carlo Simulations.

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A damage identification method based on anti-resonance frequency change was proposed. In the results of harmonic vibration response analysis, it was shown that anti-resonance frequencies were notably changed by slits in a concrete beam. The slits were made into the concrete beam specimens to examine the adequacy of proposed method. In the experimental results, it was shown that a damage location in concrete beam specimen was given by relationship between resonance and anti-resonance frequency changes. From the forced vibration tests of the concrete and steel road bridges, it was confirmed to be able to measure anti-resonance frequencies in these bridges by using a portable shaker.

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Application of a generic semiconductor device called FPGA (Field Programmable Gate Array) as a numerical simulator in the real-time experimental hybrid simulation system is investigated. Design, implementation for actual FPGA system and performance analysis of logic circuits required for high-speed dynamic simulation of MDOF structural system models are performed to discuss feasibility of real-time response simulation of large-scale MDOF structural systems using FPGA, and this approach is shown to be promising and effective in expanding the range of applicable structural models.

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A wind load is an output of a complicated system and its direct measurement is difficult. Therefore the objective of this paper is to estimate time series of a dynamic wind load against a structure in real-time, using noisy measurements in the bending-shear model. To achieve this, we propose to use the Kalman filter to obtain state estimates from noisy measurements, and to do inverse filtering from the state estimates to obtain the wind load estimates. The effectiveness of the proposed method is validated by simulation studies.

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In this study, a field experiment on a truss bridge is conducted to investigate its modal change due to member's fracture. A diagonal member is cut in the experiment and a heavy vehicle passed the bridge to excite the bridge before and after introducing damage. High repeatability of responses of the bridge and vehicle in the spatial domain is observed. Variations of the mode shapes as well as singular value spectrum obtained by FDD due to damage are observed in comparing to those before applying damage. Observations also demonstrate that the kurtosis of the independent components of bridge responses could be an index to represent variation of bridge health condition. However, in vehicle responses, it is still a challenging task to detect clear feature of modal change caused by bridge damage.

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In this paper, the lateral walking design force per person is proposed and compared with the Imperial College test results, etc. Numerical simulations considering this walking design force which is incoprated into the the neural-oscillator proposed by Matsuoka are carried out placing much emphasis on the synchronization (the lock-in phenomenon) for a congested pedestrian bridge model with the lateral frequency of 1.0 Hz. Based on these numerical simulations, it is confirmed that the analytical method based on the neural-oscillator model might be one of the useful ways to explain the synchronization (the lock-in phenomenon) of a fairly high part of all pedestrians being on the bridge.

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Recently, a Carbon Fiber Composite Cable (it is hereafter called a CFCC) has been applied for cable-supported footbridges since it is lightweight, high strength and high-corrosion resistance. However, the weight saving of a cable also induces the vibration problem due to wind action and vehicle excitation. It is necessary to investigative the damping characteristics. In this paper, two kinds of experimental studies were conducted for the purpose of clarifying the damping performance of CFCC comparing with a steel wire.

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Smart sensor systems are expected to be a suitable sensing solution for structural health monitoring of infrastructures because such sensors can transfer data via wireless network. In this study, an Imote2 smart sensor system is applied for bridge vibration measurement test. Weather proof housing with solar energy harvesting system is also developed for outdoor measurement. A cold room test of the housing has been done before real bridge measurement. The test bridge is an old pedestrian suspension bridge. Measurement results revealed that the developed solar energy system supplies enough power to a smart sensor. Natural vibration modes of the bridge are detected from free vibration data properly.

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Many studies have been reported about vibration characteristics of steel bridges due to vehicle movement. However, there are few studies concerning PC bridges. Therefore, this study is concerned with dynamic response analysis in PC connected girder bridges due to vehicle movement. In this study, the analysis was simulated about the bridge with different span length and different bearing stiffness. Road-surface of the sine wave generated from IRI value 3.5 also was used. The analyzed results show that the response of the superstructure becomes the maximum from 5 to 11m of sine wavelength, and increases along with the span length.

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The countermeasures work by reinforcing method with overlaid concrete was executed in the object bridge where the ground vibration problem was occurred. By these measures construction, it was confirmed that the ground vibration near the bridge decreased 3-5dB. According to the results of the dynamic response analysis under the running vehicle and the examination, the ground vibrations near the bridge were influenced by the road roughness at the object abutment. Therefore this study investigated the relation between the IRI_10 using the road roughness at the abutment and the vibration level of the ground vibration near the bridge.

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下記の論文は撤回されました．
記
秦吉弥，中村晋，野津厚：2011年東北地方太平洋沖地震における藤沼ダムでの地震動の評価－海溝型巨大地震へのサイト特性置換手法の適用－，構造工学論文集，Vol. 58A，pp. 250-263，2012.
撤回の理由
2019年3月15日に大阪大学より公表された研究活動上の特定不正行為に関する調査結果において，本論文に対して第一著者による特定不正行為（ねつ造）が認定されたため，撤回した．

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In order to evaluate the seismic performance of an arch dam, we have developed a three dimensional finite element model by which static behavior and dynamic properties of the arch dam can be reproduced. The seismic performance of Hitotsuse arch dam was evaluated by using this model. These results were compared with measuring data such as displacement and ambient vibration, and it was confirmed that these results reproduced the characteristic of a real dam, and then, the seismic performance of Hitotsuse arch dam was confirmed.

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After Hyogoken-Nanbu Earthquake in 1995, many studies about seismic resistance of steel bridge piers have been conducted. However, the most of those studies are only for new steel bridge piers or existing steel bridge piers which have not experienced earthquakes. Although small damages caused by earthquakes are allowed of the current design code, no method exist for repairing the damaged steel bridge pier.
In this study, we propose three types of repair methods for steel bridge piers which have local damage by earthquake. We prepared sixteen circular steel bridge pier specimens which have local buckling in the bottom of pier by previous cyclic loading experiments. After repairing them, perform cyclic loading experiments under the same load sequence as previous experiments, and evaluate seismic resistance performance of the repaired steel bridge pier.

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The paper describes the seismic performance of steel stiffened box piers. The box piers are partially concrete-filled at their base. The load-carrying capacity, ductility, and energy-absorption of box piers are numerically evaluated by Finite Element Analysis (MARC2005r3). The loading condition is one of the combinations of the axial compression corresponding to the dead load of superstructures and the cyclic horizontal load corresponding to the seismic action at their top.
The numerical computation is carried out to study the relation between their various parameters and the seismic performance of partially concrete-filled steel box piers. The influence of the height of filled concrete, the section parameter of piers, and etc. on their seismic performance is examined. Moreover, the effect of the local plate buckling of steel stiffened plates composing of box section on the seismic behavior of concrete-filled steel box piers is clarified.

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Many steel structures have been faced to the problem of superannuation in Japan. Severe damages will be caused in these structures subjected to huge earthquakes. It is necessary to secure safety of these structures to such earthquakes. Two-dimensional horizontal behavior of seismic response of structures with damages by corrosion has been hardly researched. Therefore, in this study experiments and numerical analyses intended for rectangular steel bridge piers with damages in the corners were conducted in order to evaluate two-dimensional behavior. As a result, it was clarified that the decrease of strength of steel piers with damages by corrosion was remarkable.

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In the 1995 Hyogoken Nanbu earthquake, steel structures failed in brittle failure modes that have been rarely observed before. Among them is brittle failure of a circular steel column after a severe elephant foot type buckling. These observations are followed by researches from various points of view. A convincing scenario is that an initial ductile fracture triggers eventual brittle crack propagation and it is in fact supported by some observations. The objective of this work is to pursue the possibility of a numerical analysis predicting initiation of such ductile cracks. Gurson type void damage plasticity model is modified to be valid for cyclic loading. These numerical results are compared to experimental observations.

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This study is aimed at clarifying ductile crack initiation properties of thick-walled steel beam-column members with different welding conditions and defects in the beam-column connection, and verifying an evaluation method of ductile crack initiation using a damage index. To this end, elasto-plastic analyses using the solid element model are performed in order to investigate strain along the welding defects and to calculate damage in the beam-column connection. As a result, it is shown that the ductile crack initiation in the steel beam-column connection with welding defects can be predicted with good accuracy by using the damage index. Moreover, it is also found that the location of crack occurrence cannot be predicted in some cases by the present model, though the utility of the model using solid elements has been verified by the comparison with the results of the experiment.

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Cyclic loading tests on RC bridge column specimens using deformed bars and round bars respectively were conducted and their seismic performance on failure mechanism and hysteretic characteristics of RC bridge column using round bars was discussed. The conclusions obtained from the range of the tests are shown below.(1) Rocking behavior of column occurs notably and concrete at the bottom of column is crushed due to rocking behavior of column in the specimen using round bars. (2) Above rocking behavior is mainly caused by slipping out of longitudinal rebar in footing. (3) Peak load of the specimen using round bars is slightly smaller than flexural capacity based on Bernoulli-Euler theory. Ductility is higher than specimen using deformed bars.

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In this research, experimental study was carried out for investigating the retrofit effects in case of using reinforced concrete (RC) jacketing for upgrading flexural strength and ductility of RC bridge pier that cut-off sections of reinforcement were already retrofitted with FRP sheet jacketing or steel jacketing in the first stage of the seismic retrofit strategy. Two RC pier specimens with different height of RC jacket were tested under cyclic loading test method. The influences of the height of RC jacket on failure behavior and load-carrying capacity of RC pier were confirmed based on the test results. It is concluded that the specimen with the height of RC jacket as four times of the width of column cross section provided well retrofit effects.

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This study proposed a new method for seismic retrofit of existing column connecting with retaining wall, by using toe-expanding type anchors which can fix the steel plate on the retaining wall and restrain the column from 3 directions with the plate. To understand the mechanism of the method and grasp the retrofit effects, the cycle loading test with 3 types of models (one no-retrofit and two retrofit) was executed. As a result, the effects of the seismic retrofit were confirmed. It is also understood that the strength of the anchor rod is important, which influences the restrain effects to the column to a large extent.

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Many bridges were washed away by tsunami caused by the 2011 Great East Japan Earthquake. We carried out the field survey and analyzed the damage condition of Koizumi Bridge in Mimamisanriku-cho, Miyagi prefecture. Further by using β, which is the ratio of girder resistance and wave acting force , the flow conditions of 12 tunami-dameged bridges were justified without considering the buoyancy and good evaluation of damage ranks was got. However, the damage rank evaluation by the uplift from experiment cannot good correlation with actual tunami-dameged bridges.

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Utatsu Bridge, a prestressed concrete bridge, suffered enormous damage from the destructive tsunami waves triggered by Great East Japan Earthquake, on March 11^th, 2011. Based on the field survey, the damage condition and the possible mechanisms of Utatsu Bridge have been summarized. It has been found that the girders G3~G10 suffered serious displacements while all piers did not flow out. By comparing the β value s (ratio between girder resistance and wave horizontal force) with other damaged bridges, it was confirmed that the girders did not have sufficient resistance. On the other hand, the acting moment is less than the yield moment at the base of pier column, therefore the piers did not collapse.

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This paper presents a numerical simulation method to examine the damage mechanism of bridge superstructure washed away by tsunami flow. To demonstrate a capability of the proposed method, the proposed method is applied to simulate the slab bridge behavior washed away by the tsunami flow of the 2011 off the Pacific Coast of Tohoku Earthquake (M9.0) in Japan, and the mechanism of the slab bridge damage is discussed. And also some hydraulic experimental results are compared with the numerical simulation results to confirm the validity of the proposed numerical simulation method.

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To ensure the seismic safety of steel bridge piers, it is realistic to check their dynamic responses under the coupling of 3D seismic wave components in terms of whether or not the responses are within the ultimate limit state. For this purpose, an interaction surface expressed in terms of three restoring force components and two restoring moment components around the two horizontal axes is proposed to express the ultimate limit state of steel bridge piers with stiffened square cross section. This interaction curve is versatile because it includes all the possible restoring force components that will act at the top of the bridge piers without eccentricity. The accuracy of the proposed interaction surface is confirmed by carrying out a dynamic response analysis under 3D seismic wave components.

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Seismic retrofit of an existing single-plane steel cable-stayed bridge was performed against large-scale (Level 2) site-specific ground motions. Three-dimensional non-linear dynamic response analyses were carried out considering irregularly-shaped subsurface layers. The application and effectiveness of seismic response control design using hysteretic shear panel dampers with low yield strength steel is discussed by comparing seismic response reductions of shear panel dampers with those of displacement limiting devices.

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It has been shown that one of the most efficient ways for seismic performance upgrading of steel bridges is to install energy dissipation devices (seismic dampers), such as buckling-restrained braces (BRB). There are various studies on seismic performances of isolated BRB's, however, few experiments exist in which BRBs are installed as part of a truss structure so far. This study aims at confirming the seismic performance upgrading effect of a truss structure by BRB.

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The three dimensional nonlinear earthquake response behavior of a steel arch bridge near the strike slip and thrust faults are investigated. And also, the effective seismic reinforcement methods for the steel arch bridge near the faults are proposed using the nonlinear earthquake response analyses. In these analyses, the input ground motions with permanent displacements due to the fault with the Japan Meteorological Agency Magnitude M6.5, subjected to each supports of the bridge, are simulated using the stiffness matrix method where the kinematical source model and the horizontally layered half space are assumed. The steel arch bridge is modeled as the three dimensional nonlinear frames using the Fiber Element Method.

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Previous performance tests of buckling-restrained braces (BRBs) with grade A5083P-O aluminum alloy have revealed that th e performance is inferior to steel BRBs with the identical configuration. This is due to the adverse effects of A5083P-O aluminum alloy, such as (1) large cyclic strain hardening, an d (2) decrease in low-cycle fatigue life due to welding of end ribs. In this paper, a new bolt-assembled aluminum alloy BRB with the similar configuration is proposed to avoid the adverse effects of the welding. A series of low-cycle fatigue tests have been conducted and the results show that bolt-assembled BRBs exhibit stable and excellent hysteretic properties.

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An Energy dissipation devices, such as high-performance buckling-restrained braces (BRBs) is expected to withstand major earthquakes three times without being replaced. In many cases, their capacities are clearified by tension-compression cyclic loading tests and numerical analyses. For implementing the devices to bridges and other steel structures, it is important to verify the effect of reducing structural response under a ground motion. This paper presents results of the earthquake response analysis of single-story steel portal frame with BRBs installed. And the BRBs are paid attention to by the substructure pesudodynamic testing method. By the present testing method, it is confirmed that the BRB has good energy dissipation performance.

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A proposed column is an innovative steel integrated column by multiple steel pipes based on damage control design. This study shows that a difference of design condition affects seismic response by pushover analysis and dynamic analysis. We found that a cause-effect relationship between characteristic period of this column and response of spectrum property of seismic wave affects seismic response of this column. We also compared seismic response of single column with column with rahmen structure. The result shows that seismic performance of transverse direction with rahmen structure is same or more as that of the single column.

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In this study, new rubber bearing device with fiber elements was developed. This device has high damping performance. We conducted tensile test of fiber elements, dynamic loading test of rubber bearing devices and non-linear dynamic analysis of 1-degree-of-freedom system modeled rubber bearing device with fiber elements. It was found that new rubber bearing device with fiber elements was able to reduce response displacement and dynamic load of rubber bearing device.

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Introduction of vibration control systems for bridges have advantages in terms of both seismic performance and construction cost. In applying the bridge vibration control system, it is necessary to use an appropriate model of the damper for design. The purpose of this paper is to establish the design model for the friction slip damper. The damper tests subjected to calculated response displacements for design earthquake motion were carried out, and the damping force-displacement relation was evaluated. As a result, two design models for the damper were proposed.

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The authors have proposed a “passive negative stiffness friction damper” for the purpose of the seismic performance improvement of the railway bridges. In this study, we examined the applicability of the proposed devices to the railway bridges by the parametrical analysis with simple models, the trial design and the dynamic interaction analysis for railway vehicles and bridges. As a result, we have confirmed that the devices are effective in the reduction of the structures response and the improvement of the vehicles running safety on the bridges during the earthquake by adjusting the stiffness of the devices to the value from -0.5 to -0.3 times as large as the equivalent stiffness of the rubber bearings.

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In this paper, it is reported that the wind tunnel test on parallel cables was carried out by using full sized models. And, the incidence of the wake galloping was confirmed on the original model. So, authors tried to make a study to solve this problem with two measures. Firstly, helical wires were winded for the cables in a spiral configuration as an aerodynamic measure. Secondly, some damping was added to the cable using of oil damper equipments. As a result, by setting of the helical wire or additive damping, it is confirmed that the amplitude occured from wake galloping is able to be restrained until the max wind speed in this test. In addition, the pressure features of cable surface and aerodynamic damping data on wake galloping could be obtained in this test.

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In recent years, the increase of infrastructures has become much important for the economic growth of developing countries. While, lack of budget and low technology in maintenance work make an existing bridge condition very severe with damage due to corrosion. Therefore, it is necessary to design a long-life bridge with low maintenance cost. Especially, in coastal areas, it is important to estimate airborne sea salt behavior around a bridge deck at design step. In this study, behavior of airborne sea salt particles around several types of bridge decks was investigated by wind-tunnel test with PIV technique. In addition, estimation of amount of airborne sea salt was done by a numerical simulation (computation fluid dynamics).

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To study the properties of three-dimensional flying debris, the motions of three types of plate-like debris with different aspect ratios were simulated computationally by solving 6 degree-of-freedom (DOF) motion equations and experimentally measuring six components of aerodynamic forces in a wind tunnel. The results of this simulation for a wide range of initial starting angles of attack indicated that the extension region of the trajectories of flying debris changed depending on the Tachikawa number, Ta; aspect ratio, H/B; and wind speed, U. Furthermore, it was clarified that the mean velocities for the x and z directions were not affected by rotation motion. The ensemble-averaged motion equation for 2 DOF showed that the mean velocities of the debris depended on the Tachikawa number and the averaged drag coefficient, and the lead formula fit to the results of the 6DOF motion simulation very well.

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Field vibration tests in running water were conducted on Tainter gates under practical uses in USA, with the specific intent of advancing the state-of-art knowledge concerning the coupled-mode instability mechanism for such gates, where a steel-rod breaking excitation method was adopted. The test results were the clear identification of the gate's inherent in-water vibration characteristics, which could not be revealed by the ambient test. Subsequently, the previously developed theoretical analysis was applied to the tested gate to uncover an essential dynamic instability for this installation, as well as to provide a framework for the design of a retrofit and an optimized maintenance plan.

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Effects of wind direction on the wind force coefficients, C_w, of solar panels were measured in smooth flow. The solar panels were arranged in rows in consideration that they are used at a solar panel power plant. In order to clarify the distribution of C_w, the force on a 1/20 model panel with 300mm long × 180mm wide was measured that is a part of continuous panel with much longer length. The largest C_w=1.13 was observed at the windward end when wind direction was 30°. When wind direction was small or the panel was located far from the end, C_w became smallest at around the second row and it gradually increased at further downstream. This was probably caused by flow separation from the first row and wind speed recovery with downstream distance.

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