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.

Previously, we proposed a multithread active vision system with virtual multiple pan-tilt tracking cameras by rapidly switching the viewpoints for the vibration sensing of large-scale structures. We also developed a system using a galvanometer mirror that can switch 500 different viewpoints in 1 s. However, the measurement rate of each observation point is low, and the time density is not always sufficient. In addition, strong multiple illuminations are required for the system owing to the retro reflective markers attached to the object being observed. In this study, we propose a multiple vibration distribution synthesis method for vibration analysis that increases the sampling rate of each observation point in the multi-thread active vision system, which is subsequently modified to a system that requires only one illumination by using corner cubes as markers. Several dynamics-based inspection experiments are conducted for a 4 m long truss-structure bridge model. The proposed method and system are verified via a high-order modal analysis, which was impossible to perform in the previous method and system.

This study develops a new household resource allocation model, which incorporates multiple interactions (including the interaction between time use and energy consumption, the interactivity interaction, the inter-end-use interaction, and the intrahousehold interaction) based on multilinear utility functions and endogenously represents zero consumption for both time and energy within the group decision-making modeling framework. This may be the first model in literature to jointly accommodate all these behavioral mechanisms in a unified and consistent modeling framework, especially in the context of time use and energy consumption. The model is estimated using data collected in a household survey in Beijing in 2010. Estimation results reveal that: (1) synergic effects are observed with respect to in-home time use and energy consumption, out-of-home time use across varied activities, and in-home energy consumption from different end uses; (2) competitive relationships are detected between in-home time use and out-of-home energy consumption, out-of-home time use and in-home energy consumption, in-home and out-of-home energy consumption, and time use. These not only support the joint representation for time use and energy consumption behavior but also for the energy consumption behavior of in-home end uses and out-of-home vehicles. Additionally, it is found that the intrahousehold interaction does exist.