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Globally, large-scale natural disasters are occurring more frequently due to climatic and environmental changes. In addition, the disaster risk for infrastructures, mainly bridges, has become a vulnerability issue because reinforced concrete bridge structures are being directly exposed to the natural environment. Bridge structures linking cities or prefectures are destroyed in the aftermath of natural disasters and must be rebuilt. As a post-disaster measure, rapid reconstruction of damaged bridges and the reconnection of transportation systems between impacted locations and urban areas are the main problems encountered. This study aims to solve these problems through the application of a novel concept of an emergency bridge based on origami-inspired post-buckling theory, in conjunction with previous studies investigating the optimal deployable structure of scissors-type bridges. This study applied a novel design method for scissor-type bridges that use influence line diagrams and equilibrium equations. The proposed methods can determine the size of each member appropriately while providing the minimum and maximum values of the influence line border when carrying light vehicles by analyzing variations in the live load distribution on the structure. In the case of heavy vehicles passing over a bridge, the fundamental internal axial forces and bending moments were obtained, which provided design parameters for improving the load-carrying capacity of the structure. The proposed emergency bridge has a lower theoretical stress than that of a double-Warren truss. [ABSTRACT FROM AUTHOR]

The heavy rainfall that occurred in western Japan in July 2018 caused massive and widespread damage to social infrastructures and lifelines. Certain cases that can be used to specifically and quantitatively analyze the damage situation and the cause of the damaged bridge groups are valuable for overcoming structural and complex engineering problems. Such cases can be used to identify the causes of the failure and the analysis progress, and they will help improve the design elements and construction method of bridges in the future. They could also yield such measures as washing out of the bridge at the time of flood. In this study, we conducted a field survey of the washed out Misasa railway bridge, and we evaluated the conditions that caused the failure based on hydrological, hydraulic, and structural analyses at the time of the flood, based on a field survey of the affected bridge. These analyses will help obtain design elements for small and medium bridge structures and countermeasures in the future. We focus on the collapse issue of the 1st Misasa Railway Bridge, wherein the collapse trigger of structural stability can be evaluated through its collapse mechanism. The structural analysis reveals the flood hydrodynamic force on the bridge girder during the flood that caused the collapse. In particular, when the hydrodynamic force of the water flow acts on the bridge girder part, the flood hydrodynamic force that led to the collapse of the bridge is estimated from the engineering point of view of structural stability. Based on the failure processes and conditions revealed by the analyses, we identified design elements that can help increase the resistivity of bridge structures on small rivers against floods with effective methods. [ABSTRACT FROM AUTHOR]

Autonomous vehicles (AVs) are rapidly transforming the automotive industry due to rising consumer interest in these vehicles worldwide. However, few studies have compared different countries in terms of public acceptance of AVs. This study compares public acceptance of AVs as a function of risk perceptions in two countries leading the AV industry—Japan and Israel. We set our study within the risk-as-feelings framework. In contrast to "risk as analysis," which invokes factual reasoning to bear on risk assessment and decision making, "risk as feelings" takes affective cues such as the sense of dread and unfamiliarity into judgments of risk. To this end, we conducted two web-based surveys in Japan in 2017 and Israel in 2021. In a between-subjects design, we manipulated introductory video information to portray various combinations of risk factors commonly associated with AVs: system errors, external interferences with car controls (e.g., hacking), and the inability of the AV to cope with unexpected events. Next, participants were surveyed about how they perceive the risks of AVs and other well-known technologies and activities. Results showed that acceptable risk, perceived risk, and perceived benefit of AVs were all generally higher in Israel than in Japan. The opposite pattern was found for a "risk adjustment factor," suggesting that the Japanese seek more safety before acceptance than Israelis. Furthermore, we conducted a factor analysis on seven risk dimensions, resulting in a two-factor model of dread and unfamiliarity. Cognitive mapping of AVs and other technologies and activities in the two-factor plane revealed that the AV technologies we studied (i.e., AV-car levels 3 and 4; AV-bus levels 3 and 4) have high unfamiliarity risk but moderate dread risk compared to technologies and activities such as smoking, flying, and handguns. After exposure to video-based educational content, unfamiliarity risk was less influential but dread risk—in particular, related to human-made risks—became more influential. The results indicated that manufacturers and policymakers should emphasize mitigating human-made risks instead of focusing on improving public familiarity with AVs to garner trust and improve public acceptance of the technology. [ABSTRACT FROM AUTHOR]