To further increase the speed of railway vehicles running on existing narrow-gauge track, we developed a new tilting system that enables the car body to tilt at a larger angle than conventional tilting trains. The system coordinates tilting beams and a controlled air spring height, thus reducing losses in wheel-load and avoiding lateral displacement of the car body caused by the larger tilting angle. This paper reports the features of the hybrid tilting system, the control method applicable to such tilting and the results of the bench tests carried out.

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The problem of rolling contact fatigue cracks that occur on wheel and rail surfaces is one of the most significant in the railway industry. This paper introduces a finite element method (FEM) model that has been developed for the analysis of such cracks. The model consists of FEM analysis that takes into account the local material response generated by the contact load between wheel and rail. Both the wheel and the rail are modeled using an FEM mesh, and the wheel is loaded and rotated in the rolling direction on the rail. Combined isotropic and kinematic hardening law was used to model the decaying hardening rate that is important in rolling contact situations. Stress and strain values obtained through FEM analysis were combined with the multi-axial fatigue life model and the critical plane approach to predict the onset of fatigue cracks in the railhead. The calculated results were compared to the data obtained from investigation in the field, and discussions were made.

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In order to develop some fatigue design diagrams, the authors carried out weld joint fatigue tests for an aluminum alloy carbody shell. The hollow extrusion weld joints of a doubled-skinned shell and two types of reinforced weld joints of a single-skinned shell were selected as being representative of carbody shell weld joints. The authors created a fatigue design diagram for the hollow extrusion weld joints by means of a statistical treatment of an S-N curve obtained from the fatigue tests using both small-size and full-scale test specimens. In addition, they used the full-scale test specimens in the same manner to develop a common diagram for two kinds of reinforced welds used on single-skinned shells. The diagrams were valid for evaluating fatigue strength from the stress range of materials near the weld joints.

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It is important to consider robustness when design of brake control systems, because there are the model's uncertainties which result from nonlinear characteristics of adhesion forces between wheel and rail, and friction coefficients of brake materials. This paper presents the experimental results about the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performances under nonlinear characteristics of brake dynamics.

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Hybrid electric vehicles (or Electric Multiple Units) can be defined as railway vehicles (EMU) fed by a contact feeder line (trolley) as well as an on-board electrical energy storage device. This report concerns the hybrid control algorithm for the trolley and the lithium ion rechargeable battery. Instead of being cancelled out in the usual way with an inverter-fed EMU when the trolley power supply stops, a regenerative brake using the hybrid control developed has demonstrated the performance required for the designed regenerative power continued to zero speed.

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RC piles are subject to confining pressure from the subgrade, meaning that their deformation capacity is likely to be greater than that demonstrated under atmospheric conditions. The purpose of this study is to establish a simplified evaluation method for the ductility of RC piles that are subject to confining pressure from subgrade reaction. We proposed a method of calculating this ductility with the confining pressure from subgrade reaction converted into an equivalent confining pressure from hoop reinforcements. We then conducted alternate loading tests for RC piles in a pressurizing soil-filled chamber. Finally, we compared these experimental results with those achieved through numerical simulation using the newly developed method, and demonstrated its validity.

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The deformation and cracking of mountain tunnel linings without reinforcing bars due to earth pressure has prompted a number of researchers to focus on methods of evaluating the strength of such linings as well as countermeasure design to prevent such damage. However, no satisfactory method has been found for evaluating the structural strength of urban tunnels with reinforcing bars, which offer increased safety against earth pressure. We therefore carried out model tests and numerical calculation on tunnels with reinforcing bars to investigate their mechanical properties. It was confirmed that tunnels are stabilized through the distribution of stress, even with the reduced stiffness and strength values obtained using the numerical calculation method described in this paper.

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Over-track buildings require seismic performance enhancement as well as minimization of the vibration propagated by trains running below them. To this end, we have proposed a structural system for a building with functions to isolate both seismic and vibration effects. In this system, laminated rubber bearings that are softer in the vertical direction than general ones are set into the middle story of the building. Through response analysis, this study demonstrates a high level of seismic performance, and the reduction of train-induced vibration is confirmed using model experiments and numerical analysis.

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The increasing costs of design and construction to combat the effects of liquefaction caused by major earthquakes are often considered, as conventional methods of evaluating the strength ratio suggest that the probability of liquefaction is high. The results given are not representative, and evaluation is made on the safe side in diluvial soil. We therefore carried out a systemized investigation into soil quality to understand the strength ratio that causes liquefaction in diluvial soil. The results confirmed that cementation was present in older sedimentation areas, and that the large amounts of fine-grained soil found there provided around twice the strength of alluvion soil. In addition, we suggest a design method based on these results. In diluvial soil, improvements in the rationality and economy of designing and building structures against liquefaction, as well as liquefaction countermeasures, have been made possible thanks to the increased precision of evaluating liquefaction.

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