This study presents an analytical approach to novel damage identification methods for simply supported bridges using displacement responses of girder ends. The rotation at the hinged support, deflection at the point of load application, and shortening at the roller support are emphasized. Three damage parameters for its location, severity, and area are considered. Normalization by the maximum response is introduced to eliminate the weights of running vehicles, and single damage is defined as an equivalent point load by reducing flexural rigidity at a particular point along the beam. The targeted structural responses under intact and damaged conditions are derived using the conjugate beam method, and several damage scenarios are investigated. Results show that it is reliable for the estimation of damage localization owing to damage-sensitive properties with a considerable capability of identifying the quantity of damage severity.

 Many cases of fatigue cracks at welded joints at the front of sole plates in steel bridges have been reported, and the causes of crack generation and countermeasures have been studied. However, studies have so far mainly focused on corrective maintenance, and practical preventive maintenance measures have not been established. In this study, focusing on the toe crack and root crack that occur at the welded joint at the front of the sole plate, preventive maintenance measures using peening treatment and tap bolts were studied by FEA and fatigue tests. As a result, it was clarified that the peening treatment can improve the fatigue strength of the weld toe of the sole plate when compressive stress is induced at the weld, and the method using tap bolts could extend the fatigue life of the weld root of the sole plate.

 For visualization of tensor fields, we propose a new method of obtaining a set of iso-surfaces whose gradients are parallel to a given vector field. While a streamline is drawn line by line, the new method can draw a set of surfaces simultaneously, from which an assembly of streamlines can be drawn at once. The method is applied to the visualization of stress in two-dimensional (2D) elasticity problems to show its usefulness. Results show that iso-surfaces parallel to the principal stress fields can be visualized using the proposed method and show that i) it is much easier to draw overall streamlines and ii) local streamlines can be constructed for complicated configurations. The proposed method for drawing iso-surfaces conjugate to streamlines can be considered a natural extension of the visualization of vector fields using streamlines to tensor fields and is expected to be useful for the visualization of other symmetric tensor fields.

 Although Zone 30 is being rapidly implemented in Japan to improve pedestrian traffic safety, its impact on the number of traffic accidents over time and its relation to land use is still unclear. This study analyzes changes in the number of traffic accidents in Zone 30 areas before and after implementation. To this end, a time-series analysis of traffic accidents in 10 Japanese prefectures was conducted. The results show that the policy reduces the number of Killed or Seriously Injured (KSI) traffic accidents in a 2-year before-and-after comparison. The study also investigated the relationship between the policy’s impact on an area and its land use. The results indicate that the type of land use in an area affects the change in the number of traffic accidents following the implementation. These findings suggest that observing the target area and understanding its characteristics, such as land use, are necessary for effective regulation.

 This study presents a method for evaluating the safety and durability of existing concrete bridge super-structures using a performance correlation chart featuring margin and deviation ratios. The assessment focuses on reinforced concrete slab and prestressed concrete plank girder bridge superstructures in Thailand’s Eastern Economic Corridor, under the Department of Highways. The level of structural safety is assessed through the safety margin ratio, while the level of durability is evaluated using the durability and deviation ratios. The proposed method facilitates a clear interpretation of structural performance by linking safety and durability levels. Based on the findings, the design enhancements aimed at improving structural performance are recommended. The proposed design method offers a practical framework for enhancing long-term performance and promoting durable bridge structural design.