This paper reviews the history of the development and use of high strength steels for bridge structures in Japan. The required performance of high performance steels for bridge are proposed. The new steels BHS500, BHS500W and BHS700, which satisfy the proposed required performance, were developed. The basic properties of the developed steels are tested and the results are shown. The trial design using the high performance steels was done. It gives the example of economical benefit by the use of developed steels. Also the excellent welderbility is proved, therefore benefit is obtained from fabrication process.

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The difficulty of modeling underground structures is a bottleneck in quantitatively studying earthquake phenomena. Stochastic modeling that accounts for the uncertainty of modeling is an alternative, and the authors have been developing two analysis methods for a stochastic model. This paper presents these methods in a unified manner, emphasizing the efficiency of numerical computation. The earthquake wave propagation and the surface earthquake fault formation are solved as examples, and the results are compared with observed data to examine the validity and limitation of the analysis methods of the stochastic model.

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In post structures supporting traffic signs or lighting apparatuses on highway bridges, strengthening gussets welded at the bottom of post introduce stress concentration and make these details susceptible to fatigue failure. Stress and deformation near critical points in normal and improved type post structures are comprehensively studied with 3D finite element analyses. Fatigue evaluations are carried out with HSS method and one-millimeter stress approach based on finite element analyses. Fatigue strengths are suggested based on test data and evaluations. It is found that one-millimeter stress approach is suitable for fatigue evaluation of post structures and that thickness correction is necessary in HSS method evaluations.

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A numerical procedure for crack width evaluation of steel-concrete composite girder bridges under negative bending moment is proposed. The procedure is combination of 3-dimensional finite element (FE) analysis with smeared crack model and a bond-slip differential equation. From the FE analysis, the averaged behaviour including shear-lag as well as cracking is calculated. Then, the crack width is evaluated by using the differential equation and the FE results. Attention is paid to the consistency between the FE modelling and the employed bond-slip differential equation. The obtained crack widths are shown to compare well with those from experiments on composite girder specimens.

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A countermeasure against near-source ground motions should be established based on careful examinations of their characteristics. Since a tendency has been found for the strike-normal component to be predominant in the near-source region of a large intra-plate earthquake, it is expected to be a reasonable decision to orient important quay walls perpendicular to the strike of the active fault of concern. For the purpose of validating this decision, two kinds of analysis are conducted, namely, ground motion simulations to show the effects of fault parameters on the predominant direction of near-source ground motions and non-linear FEM analyses to show the effects of quay wall orientation on its residual deformation.

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Hysteretic ultimate behavior of inverted L-shaped steel bridge piers filled with concrete under out-of-plane cyclic loading are studied by experimental tests and numerical analyses. The cross-sections of models are non-stiffened box section and stiffened one. The height of filled concrete are changed as a main parameter. The width-thickness ratio of the component plate is about 0.8, the slenderness ratio is about 3.0, the eccentricity ratio e/h (the ratio of the distance e between vertical load and vertical pier axis to the height of pier h) is 0.4. The results of FEM analysis are compared with the experimental results. The hysteretic behaviors of FEM analysis agree well with those of the experiments.

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This paper describes the vibration characteristics of glass fiber reinforced polymer (FRP) footbridges having the rigid-jointed truss system with a span of 32m. The force-time history of pedestrian in walking and jogging modes is arranged as a set of parameters suitable for finite element analytical modeling. Comparsion with steel truss footbridges, the FRP ones are easy to vibrate in horizontal direction due to a 700N test pedestrian model, but it would also be reduced by changing only a few specific members into carbon FRP shapes.

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The shape of 2-dimensional elastic body is optimized to minimize the compliance under the condition of the constant volume. The optimization problem is formulated based on the variational principle which considers the change of domain shape and analyzed using the finite element method and the boundary element method. The optimization of the height of cantilever is discussed to confirm the validity of the present theory and the numerical procedure. The optimal design of the shape of hole under the biaxial stress is solved as a representative example of the exterior problem.

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This paper presents an experimental study on the residual strength of concrete filled tubes damaged by rock collision. We carried out two kinds of tests to obtain the residual strength and the residual energy absorption capacity of damaged concrete filled tubes. First, the weight dropping test was conducted to give the damage to the concrete filled tube. Second, the static and rapid speed flexural test were performed to obtain the load-displacement relation and to investigate the speed effect on the residual strength and the residual energy absorption capacity. We could propose the serviceability limit and the ultimate limit of the damaged concrete filled tube as the residual deformation angles θ=1° and θ=5°, respectively.

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This paper presents a simulation method of debris flow entrapment behavior of the open type check dam by using the 3-dimensional distinct element method. First, small model experiments are conducted in which various size of gravels flow down and clog in the open space of the framed check dam structure. Second, a cylinder element that put as the frame structures entrapping the large scale granulars is installed in the 3-dimensional distinct element method. Several improvements are also proposed. The simulation results of the proposed method match the experimental results quite well.

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An efficient and highly accurate method by using hierarchical finite elements is presented for the analysis of local stresses that are caused by the stress concentration in the vicinity of singular points. Singular elements are used to prevent the deterioration of convergence of the solution in the case of having singular points. In this study, hierarchical curved elements with many singular points are developed by using singular mapping functions. The accuracy and availability of these elements are demonstrated by numerical examples.

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The modeling of waves is often used to investigate ground wave propagation properties because of the complexity of actual ground motions. In this paper, the method of normalized input-output minimization (NIOM) is modified, and this modified NIOM method is used to analyze microtremors recorded at three different vertical-array sites in Japan. The main features of this study include using simultaneously recorded vertical-array microtremors, finding the direction of wave propagation by modeling the observed correlated waves, and obtaining the average particle motion to determine the type of wave present.

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In many design cases of transmission towers, wind loads of the typhoon and seasonal wind are dominant, and it is important to consider dynamic effects of tower-conductor systems, such as scale effect and resonance effect, as well as the winds effected by topography and the wind direction. In this paper, wind load evaluation formulas considering the dynamic effects based on gust loading factor and the reduction coefficients to estimate influence of non-simultaneity between tower and conductors are proposed systematically for rationalization of design wind load. Through the comparison of present method with dynamic response analyses by FEM, it is confirmed that the present wind load evaluation method is applicable to arbitrary location of cables and arbitrary wind directions.

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The hysteretic behavior of reinforced concrete bridge columns depends on the hysteretic behavior of reinforcing bars. The model proposed by Giuffre, Menegotto and Pinto has been widely used as a nonlinear hysteretic model for reinforcing bars because of its simple but accurate expressions. However, the model often develops an unrealistic sudden change of the stiffness resulted from partial unloadings and reloadings. In such cases, the Bauschinger effect cannot be represented. A modified model for the original Giuffre, Menegotto and Pinto model is proposed by Eqs. (10), (11) and (19) so that realistic hysteretic stress vs. strain relations after partial unloadings and reloadings can be evaluated.

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Pressure fluctuations in a tunnel induced by a high-speed train at over 500km/h were investigated in this study, to realize the rational tunnel lining design. Full-scaled measurements of the tunnel pressure were carried out in the Yamanashi Maglev Test Line to understand the characteristics of the pressure fluctuations. Numerical simulations of the pressure fluctuations were also made, and the theoretical formulas to estimated the pressure fluctuations were modified to use in the higher Mach number region of the train speed, based on the numerical results. The evaluated values from the formulas were carefully compared with the data obtained from the full-scaled measurements. The validity of those formulas was confirmed by the results of those comparisons. The maximum pressure fluctuations induced by the train moving through a tunnel were evaluated to design the tunnel lining used in the high-speed train tunnel such as for a maglev linear motor vehicle.

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It is well known that seismic ground motions are characterized by source, path and site effects. In order to estimate seismic intensity taking into account those effects, we propose a method to estimate site effects on seismic intensity based on site amplification spectra. Numerical and empirical analyses are performed to examine the relationship between site amplification spectra and increments of seismic intensity which is obtained from simulated motions, observed motions and questionnaire survey. It is clarified that the increments of seismic intensities can be evaluated by average values of site amplification spectra from 0.4Hz to 7.5Hz.

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Presented in this paper is numerical analysis of seismic performance of inverted L-shaped box-section steel bridge piers subjected to out-of-plane cyclic loading. The validity of the analytical model is verified by comparisons of hysterestic curves and buckling modes between the analysis and large-scale test specimens. From the analytical results, it is realized that the eccentric vertical load and cyclic loading pattern will cause a significant in-plane displacement, and in the case of inverted L-shaped piers, strength deterioration is greater than that of T-shaped piers. Furthermore, an extensive parametric analysis is performed to propose empirical formulas in order to evaluate strength and ductility of inverted L-shaped box-section steel piers.

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The present study focuses on the input loss of deeply embedded foundations that support bridges and viaducts. It is widely known that the strain dependency of soil dominates in surface layers supporting the foundations when subjected to strong motions. Therefore, it is desirable to know how the input loss is affected by the strain dependency accompanied by changes in stiffness and damping of soil. This study investigates the influence of strain dependency on the input loss by means of vibration tests and a theoretical approach of a closed form solution of input loss with a constitutive model for the nonlinearity of soil. The present study gives physical understanding for the relation of the strain dependency and the input loss.

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A structural analysis is developed in order to evaluate the long term mechanical performance of steel structures by taking into account the effects of the histories of corrosion loss of material and repair. This analysis is characterized by the point that the volume change in material due to corrosion or repair is adopted as a new controlling parameter along with the conventional parameters such as load and displacement. With the proposed analysis method, it is examined how the seismic behaviors of the repaired bridges are influenced by the difference of the repair methods in comparison with that of the corresponding virgin bridge.

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If fatigue damage or its possibility can be estimated easily and economically, the efficiency of maintenance inspection for steel bridges is considered to be drastically advanced. For this purpose, a system in which thin stainless steel with a crack is stuck on a bridge to measure crack propagation and the cumulative amount of fatigue damage has been developed. In this study the quantitative relationship between an amount of crack propagation and the fatigue damage has been made clear, and the applicability of the fatigue damage monitoring sensor and its accuracy have been examined through an analysis of stress intensity factor range the and a fatigue crack propagation test.

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According to the increasing of 2- or 3-plate girder systems and open-box girder ones in short- and medium-span highway bridges, the span lengths of concrete slabs have become longer than the one of ordinary multi-girder systems. As one of the method dealing with this problem, 2-way slabs supported by main girders and cross beams seem to be effective because of not only reducing the bending moment caused by wheel load, but also improving the durability by relaxing shear concentration by arranging main reinforcements parallel with moving wheel. Therefore, in order to certify the deterioration mechanism of the 2-way slabs, fatigue tests by using wheel-running machine were carried out Then, a FEM analysis modeling the cracks by gap elements with rotational and shear spring, was developed and the test results were evaluated with the relation between the influence of strength and repeating number of wheel load on the decreasing stiffness of the slab and the deterioration rate.

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Systematic study to derive alloy indices related to anti-corrosion performances of weathering steels at any given construction site, was carried out. Also, an accelerated corrosion test method was developed to evaluate the relative weathering quality of recently developed Ni added high performance weathering steels. To avoid any anomalous corrosion to occur on existing unpainted steel structures in future, it is very important to confirm at design stage, if Y_(X=50)≤0.3mm or Y_(X=100)≤0.5mm is established or not, referring environmental corrosiveness as well as anti-corrosion properties of weathering steels. Such assessing processes will be much facilitated than ever, by the methods described in this paper

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The new real-time disaster mitigation system for a city gas network has been developed by Tokyo Gas Co. for the purpose of realization of dense real-time seismic motion monitoring, quick gas supply shut-off, prompt emergency response and efficient restoration work since 1998. In 2001, Tokyo Gas successfully started operation of SUPREME, which employs 3, 700 new SI sensors and remote control devices. The SUPREME can observe the status of 3, 700 district regulators and shut them off remotely, if necessary. The remote shut-off using SUPREME can realize quick gas supply shut-off and effectively reduce gas leakage risk during earthquakes. The SUPREME can also conduct damage estimation for gas pipe with enhanced use of GIS.

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Broken wires of an old suspension bridge in USA were investigated. Tension strength, elongation, chemical composition of the broken wires are almost the same as those of the recent galvanized high strength wires. However, the torsional strength is low and high residual stress exists due to the bent shape. Observation of fracture surface with electrical microscopes indicates that the crack initiation position is the corrosion notch on the wire surface. The crack gradually progresses from that point and beech-mark like stripes appear. Since the fracture surface is similar to a typical fracture surface of corrosion fatigue failure specimen instead of hydrogen embrittlement specimen, it is estimated that the wire breakage occurs by the mixed effects of corrosion, fatigue and hydrogen.

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In conducting model wave experiments, there are occasinally technical problems of exciting apparatus when a model is subjected to arbitrary-type input. In such a case, wave phenomena of a model can be obtained simply by calculating the superposition of responses caused by an impulse. In this study, the accuracy of such a method was estimated as follows. Displacement time histories of an elastic layer model were measured when a half-wavelength impulse type input was applied. Time histories for several sinusoidal inputs were then calculated by the proposed method, and were compared with those obtained experimentally. The good agreement between the results indicated the validity of this method.

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