The purpose of this study is to identify the causes of fatigue cracks found in a plate girder-on-steel frame pier bridge. The complexities of this type of structure make the stress configurations near crack locations complicated. A three-dimensional finite element model, incorporating both superstructure and substructure was created to study the stress development mechanisms near crack locations. Field tests were carried out to investigate structural behaviors, such as conditions of bridge bearings, and to validate the finite element modeling. The results indicate that fatigue cracks are caused by dysfunctional bridge bearings, poor structural details and deformations of some members.

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A swarm of earthquakes began in the northern portion of the Gulf of Aqaba on November 22, 1995 with amaximum local wave magnitude of M_L 6.2 and focal depth of about 15km, causing damage to buildings in the Aqaba region. More than 8000 after shocks were recorded during the next 40 days. Observations related to damage to structures and soil liquefaction are presented by photos and discussed. Generally, engineered low-rise buildings with one to four stories above ground behaved satisfactorily. The hotel area in Aqaba on the shoreline appears to be riskier for flexible buildings during major earthquakes. Therefore, denser inland alluviums or rock sites should be considered for constructing new high-rise buildings and hotels.

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Mechanical behavior of concrete filled circular steel tubes with extremely thin walled tubes over the domestic limited ratio of diameter to thickness: D/t under centric compression was examined experimentally, with an economical view of application to the bridge columns. Twelve specimens ware prepared, where selected test parameters were D/t and concrete strength. As a result, their strengths attained to the estimation values considering confinement effect of concrete beyond the simple accumulative strengths, if sufficient countermeasures were executed from the tube manufacturing to filled concrete placement stage. Furthermore, the observed failure modes were a diagonal slip of core concrete with an elephant foot like buckling at the end of the tubes.

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This paper presents several derivations of 3-dimensional structural strains of a shield tunnel under an earthquake ground motion. Theoretical expressions including not only axial and bending strains but also cross-sectional strains of a tunnel are developed in order to discuss the applicability of spring modulus and current seismic design methods.
Numerical results suggest that the tunnel strains are dependent upon the lining rigidity, so that a tunnel with small lining rigidity shows a large bending strain exceeding the critical strain of 1% given in the current design method.

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A method for assessing the seismic stability of arch dams has been developed in the study. With the method the earthquake, observed at an existing arch dam, of its maximum acceleration over 700gal has been simulated. Furthermore, the response analyses of the dam subjected to a strong earthquake of the maximum amplitude 500gal at the dam base have been carried out. The dynamic behaviors of the contraction joints and the effects on the earthquake responses of the dam have been analyzed. It has been pointed out that the nonlinear behaviors of the contraction joints exert significant effects on the responses of the dams struck by strong earthquakes. And reservoir water has a favoring effect on the earthquake resistibility of the dam. Finally, the earthquake resistibility of the arch dam against very strong earthquakes has been given.

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Cracks inside steel plates were found under the retrofit welding of steel bridge piers. By Z-direction tension tests using cores from the piers, the analyses of chemical compositions, and direct microscopic observations, the cracks were proved to be lamellar tear cracks, which are due to old and bad property steels. Also, by paper researches on old documents, it is found that there are risks of lamellar tear for piers, which were constructed before 1973. Especially for steels having sulfur more than 0.01% and RAZ less than 15%, careful examinations must be than to use welding for retrofitting works. A basic plan for the examination is proposed in this paper.

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This paper describes the flexural strength and ductility of reinforced concrete bridge columns under bilateral loadings. Under a constant vertical load, the columns were subjected to bilateral loadings with four orbits (oblique direction to the strong axis, rectangular, circular and ellipse). A fiber element analysis was conducted. It was found that the deterioration of strength and ductility capacities of the columns resulted from the bilateral loadings is substantial, and that the fiber element analysis is effective to reproduce the hysteretic behavior of the columns under bilateral loadings.

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This study deals with the numerical simulation of the vibration level, L₁₀, which is required to predict the traffic-induced vibration. First, the unit pattern of vibration level is developed on the basis of the analytical solution for ground vibrations generated by a vehicle model, which moves unilaterally on the surface of an elastic half space. Secondly, the arrangement of vehicles and the mixing state for various types of vehicles are given by using the Monte Carlo method. The value of vibration level is obtained at a regular interval by the level summation of unit patterns corresponding to vehicles. The validity of this simulation is examined by comparison with measured values.

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Quantitative evaluation of the effect of the uncertainty is essential in various aspects of engineering problems. This paper proposes an efficient method to consider the uncertainty of boundary conditions, Spectral Stochastic Boundary Element Method (SSBEM). In SSBEM, Karhunen-Loève representation of uncertain boundary conditions and approximation of the solution in the finitely truncated homogeneous chaos enable efficient computation of problems with uncertain boundary conditions. Numerical examples including comparison with Monte Carlo Simulation reveal the applicability of SSBEM to both elasto-static and elasto-dynamic problems with uncertain boundary geometry.

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In our previous paper, we described vibrations with circumferential mode number n=2 when a frequency of a pressure pulsation in a turbine coincides with the natural frequency of a steel penstock. We proposed the use of natural frequency calculation formulae based on numerical analyses that target n=2, 3 vibrations. We further pointed out that the vibration (n=2) prevention by circumferential stiffeners was not remarkable. Because a limited number of papers are available describing experimental or analytical vibration studies, we performed 1/4 scale model experiments on pressure pulsations with the parameters of plate thickness and the presence of stiffeners. Based on a comparative study of experiments and numerical analyses, we proposed modification of the vibration prevention specifications stipulated in the current technical standard.

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The present study focuses on the resonant characteristic of a soil-deeply embedded circular foundation-superstructure system under compounded nonlinear conditions when subjected to lateral harmonic excitations. In this study, vibration tests are carried out. In the tests, the strain-dependent characteristic of soil layer, the boundary nonlinearity at the interfaces between the soil and foundation and the yielding of soil near the foundation are observed. It is concluded from the test results that, the shift of the predominant frequency toward the lower frequency region is mainly affected by the decrease in the stiffness of soil-foundation system due to the nonlinearity, rather than the effect of interaction between the soil-foundation system and the superstructure under small deflection condition.

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The present study focuses on input loss of deeply embedded foundations that support bridges and viaducts. It is predicted that the strain dependency of soil dominates when subjected to strong earthquakes. Moreover, slippage and separation occur at the interface between soil and the sidewall of the foundations, as well as the yielding of soil near the foundations. In this research, analytical studies are performed to simulate the resonant curves obtained from the vibration tests by means of the analytical method developed for estimating the effective seismic motion and the rocking impedance directly under such nonlinear conditions. In conclusion, the effect of input loss tends to increase as the compounded nonlinearity dominates, especially due to the nonlinear behavior of soil near the foundations.

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In the current design method of HSFG bolted joints in plate-girders under a bending moment, flange joints and web joints are designed individually. However, flange joints and web joints resist bending moment not individually but cooperatively. An analytical examination is hardly performed now. Although an experimental examination is important, an analytical examination is also necessary to obtain the reliability of the experiment result and to evaluate detailed strength. In this paper, to analyze HSFG bolted joints under a bending moment, the slip mechanism of HSFG bolted joints is modeled. Furthermore, a rational evaluation method on the limit strength of HSFG bolted joints in plate-girders under a bending moment is proposed, in consideration of cooperative performance of flange and web.

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Under approaching winds possess non-stationary stochastic processes, the ordinary method of the gust response analysis in frequency domain is not practical and it is impossible to predict the maximum amplitude of the gust response of structures. In order to overcome this underlying problem, a wavelet-based method to simulate gust responses is suggested. The time-scale characteristics present in wind fluctuations are configured with the system of the discrete wavelets and are reflected to the time histories of the gust responses to be synthesized. The time histories of the gust responses simulated with the proposed method are investigated specifically in respect to the peak factor.

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A report of recent severe earthquakes indicates that, in addition to the damage along longitudinal direction, lateral and rotation motions of bridge girders caused by pounding to adjacent girders can lead to unseating. This paper presents two multi-dimensional models that are practically suitable to precisely analyze pounding between bridge girders. One is a two-dimensional rigid body model, which is applicable to the analysis of spring-mass models. The other is a three-dimensional contact-friction model, which is developed by combining the concepts of the impact spring and contact analysis, and can be easily accommodated in finite element analyses. Two-dimensional girder pounding experiments were conducted and the motion was accurately measured using image analysis. Both models are found to well simulate the pounding effects in comparison with the experimental results.

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This paper presents a new lateral reinforcement arrangement in concrete bridge columns. Authors propose the interlocking oval hoop, which will enable wide rectangular columns to be ductile without cross ties and thus reduce the construction work. Quasi-static cyclic loading tests were conducted for specimens with interlocking oval hoops, and flexural performance of columns were discussed with comparisons to columns with rectangular hoops, circular hoops, and interlocking circular hoops. Test results interestingly showed that the reinforced concrete columns with interlocking oval hoops exhibited similar flexural performance to the conventional interlocking columns with circular hoops, when the bending-radius-ratio of the oval is smaller than 2.39.

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A new GIS-based digital map of ground conditions “Japan Engineering Geomorphologic Classification Map” was developed for all of Japan, consisting of a total of approximately 380, 000 grid cells of 1×1km each in size. The methodology for creating the map was developed by grouping geomorphologic units that are expected to have similar ground conditions. Applicability of the map for site amplification evaluation was examined. The result was found to yield the good estimate of the site amplification ratio, suggesting that the Japan Engineering Geomorphologic Classification Map may be conveniently used for the estimation of the strong motion distribution of a large area in Japan.

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A non-local voxel FEM is developed for simulating the failure phenomena of heterogeneous brittle materials. The micro-scale or meso-scale morphology of heterogeneous materials is realized by the image-based modeling technique, whereas the cracking is simulated by the element vanish technique. Also, the nonlocal technique of integral-averaging type is effectively utilized to avoid both the stress oscillation errors on the material interfaces and the spurious dependency on the voxel size for crack propagation problems. The three-dimensional numerical simulations successfully demonstrate the cracking phenomena induced by the micro-scale heterogeneities and the so-called biaxial effect that is typical in the strength characteristics of concrete.

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A lot of fatigue damage has been reported in steel highway bridges sustaining great number of heavy trucks, and the fatigue assessments have been specified explicitly from the revised edition of “the Design Specification for Steel Highway Bridges” in March 2002. A concrete manner of the assessments is specified in “the Fatigue Design Recommendations for Steel Highway Bridges”. Fatigue design load specified in the Recommendations is based on the T load whose weight is modified by T-load correction factor, simultaneous loading factor and fatigue impact factor.
In this paper, the simultaneous loading factor has been discussed, which is considering the effect of the increment of the stress on fatigue behavior by simultaneous multi-presence of vehicles on the bridge.

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A basic study is conducted on damage detection of a dynamic system using Monte Carlo filter (MCF) algorithm incorporated with Non-Gaussian process noise and knowledge based selection of process noise to detect structural damage. Because the MCF is a random sampling technique, the identified results are strongly affected by sampling realizations. In this paper we investigate the accuracy and stability of identifying process using the detectability ratio, which is defined as a ratio between the total and good results of identification. Because the optimal observation noise is related to the amplitude of input earthquake motion, we propose an algorithm which can control observation noise adaptively to the observation error level. Numerical examples reveal the effect of number of samples, observation locations, and damaged points on the stability and accuracy of identified results.

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To detect the natural frequencies of the structures under subjection of various external forces, high accurate structural identification is indispensable. Also, automated monitoring system would be effective for long term vibration-monitoring at site. For the purpose of establishment of the High Accurate Structural Vibration-Estimation Method and realization of the automated measurement system, the authors proposed an analytical method, which consists of AR model by the structure's ambient vibration. This paper shows the details of the method and the results of simulation on an arch-bridge, held to verify its efficiency. As a result, this method was verified to be efficient for distinguishing the structure's proper frequencies from external ones in details.

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In recent years, methods of evaluating the crack width in concrete slabs and those of the stress in reinforcing bars at intermediate supports in continuous composite bridges have been proposed. They are applicable to evaluation of the crack width and stress in reinforcing bars at the stabilized crack state (fully cracked state). In many actual bridges, however, the initial crack state has been observed under the hogging bending moment. In this paper, employing formulas recommended in a current method and CEB/FIP-90, a method of evaluating the crack width and stress in reinforcing bars is proposed, in which the crack width and stress in reinforcing bars for both initial and stabilized crack states can be dealt with.

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As a method of connecting two concrete-filled circular steel tubular constructions, a simple sleeve joint in which a small diameter tube is inserted with the specific length to a large diameter tube with concrete filling the gap between two tubes has been proposed as an economical and effective joint connection.
The T-shaped joint specimens which made the parameter the path of the shear connector on tube faces and the plate welded to the small diameter tube, thickness of a large diameter tube, length of a large diameter tube, etc. were tested in order to investigate the failure mechanism and the ultimate strength of the joint connection. The test results indicate that the parameters affect the ultimate strength of the joint connection greatly. In this paper, we propose the equation for calculating the ultimate strength.

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By employing CG techniques, we herein present a versatile and accurate method to visualize the numerical results for the 3D seismic analysis of framed structures such that their over-all behavior can be grasped directly in terms of CG pictures. In this method for visualization, we include a rational procedure to magnify the small deformations of beam elements under the beam assumptions. The CG pictures of large deformed 3D beam elements are produced only from the nodal kinematic data such as displacements and rotations calculated by the usual commercial FEM soft wares. From numerical examples, it is confirmed that various large deformed shapes are accurately reproduced by the proposed method even with small number of nodal kinematic data.

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Variable dampers are effective to mitigate the seismic response of bridges. This paper clarifies the application of MR-dampers (Dampers using the magnetic rheological fluid) to the variable dampers. A cyclic loading test was conducted for a MR-damper with the maximum damping capacity of 100 N to study its performance under four control algorithms; (1) viscous, (2) nonlinear viscous, (3) friction, and (4) 2-step friction. Then a series of shaking table test was conducted for a model bridge with the MR-damper to clarify the seismic response of the model bridge. An analytical simulation was also conducted.

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A new code for the design of the guard fence performances was implemented and issued in April 1999 in Japan. In the new code, the full-scale experiment for checking the performances of guard fences is required in the determination of the structure of the guard fence. However, it is very difficult to test the performance of full-scale guard fences in the field for the parametric examination because of the huge time and cost consumption. In this study, the numerical analyses under the simulated condition of the truck-to-fence crash have been carried out for the steel bridge fence. Firstly, the tensile coupon experiment is conducted to determine the stress-strain relationship and the strain rate effect of materials. Secondly, the analytical results are compared with the field experimental results. Finally, The results of analysis are used for checking the performances of guard fences.

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The Fatigue Improvement method using low temperature transformation (LTT) welding material for bridges in use was examined by welding tests, girder-model fatigue tests, and residual stress measurements. As the results of these examination, it is found that careful examination in installation is needed, if the structures have webs thinner than 12mm, and steels softer than SM570, and LTT weld is installed both sides of webs at the same point. Bt using adequate type of LTT material and keeping the heat imput smaller than 13kJ/cm, JSSCD class fatigue performance is obtained.

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This paper presents a stochastic element free Galerkin method for the problems involving random material property. The stochastic process in the material is represented by perturbative expansion as well as Polynominal Chaos, and implemented into Element Free Galerkin Method (EFGM). 1-dimensional linear elastic problem was solved by the proposed method and compared with Monte Carlo Simulation for the verification purpose. Besides, the characteristics in the results of both perturbative expansion and Polynominal Chaos are discussed. The present approach is distinguished in that it not only can consider the uncertainty in material property, but also requires no nodal connectivity for mesh construction. The present approach can be useful in analyzing the problems with complex geometry and stochastic uncertainties.

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Of RC caisson breakwaters located in the sea area of severe wave conditions, the local damage with holes has been occasionally caused by the repetitive collision of precast concrete armor units. To take an effective measure of protecting local damage in the RC wall of breakwater, the colliding behaviors should be investigated. Thus the static and horizontal impact tests for RC plates, scaled by 1/6.4 of caisson breakwater, were executed. Based on test results, the damage mechanism was examined by the relation between colliding velocity and number of repetition of impactor. And, it can be found that attaching the rubber pad to impact face is of effective to protect RC plate from local damage.

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We have proposed a simulation method of fault rupture process and generation of seismic waves at the same time using a three dimensional nonlinear finite element method. However, since there were neither pre-processor nor post-processor, long time and special knowledge were required to create input dataset in order to analyze a fault rupture process. To solve this inconvenience, we developed input and output processing systems using on-line CGI and Java. To achieve the purpose, we perfomed parametric study to determine default values for the constitutive relationship of the 3-D joint element. Thereby, shortening of the time taken at the time of data creation of an analysis model was realized and people without special knowledge also can create a model easily, and perform a simulation.

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An inversion of source process in consideration of the envelope of filtered-acceleration time histories has been performed for real-time prediction of seismic intensity distribution. On the basis of the earthquake motion prediction model, EMPR, this method estimates the relative contribution ratio of seismic power on the fault plane. The technique has been applied to the 1999 Chi-Chi Taiwan Earthquake, and the frequency-dependent asperity was demonstrated.

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