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Before the anticipated Nankai Trough earthquake, the effects of multiple cascading hazards on bridge performance and the associated functionalities of road networks must be assessed to develop recovery strategies. This paper presents a framework for assessing the probabilistic connectivity of road networks exposed to both ground motion and tsunami, considering the spatial correlations among hazard intensities. To evaluate the joint probabilities of bridge states (i.e., passable and impassable states) and the probabilistic connectivity of road networks, the total probability theorem was used to integrate spatially correlated seismic and tsunami hazard assessments into the fragility estimates that consider the cascading effects of ground motion and tsunami-induced damages to bridges. For illustrative purposes, the probabilistic connectivity of hypothetical road networks in Japan that could be affected by both ground motion and tsunami during the anticipated Nankai Trough earthquake was assessed using the proposed method. The results showed that seismic retrofitting of bridges located along the route where the probability of impassable states due to tsunami is very low can enhance the probabilistic connectivity of entire road networks. [ABSTRACT FROM AUTHOR]

This paper describes the state of the art of structural steel reuse in Japan. A significant part of the material is taken from a document titled the Architectural Institute of Japan (AIJ) Recommendations for Sustainable Steel Building Construction (Draft) available only in the Japanese language. The motivations for and potential benefits of steel reuse are examined. The affinity between seismic design requirements and steel reuse is highlighted through a concept known as "damage-control" design. Some technologies for disassembly are introduced. The historical development and changes in Japanese structural steel are summarized, followed by a discussion on reusability of historical steel reclaimed from existing buildings. Reuse projects whose details are known to the authors are listed. The heart of the paper is a design procedure that specifies the structural engineer's role and involvement in planning, material procurement, and executing a steel reuse project. The discussion is concluded by six directions that should be pursued to make steel reuse a widely accepted reality in Japan. Among those directions are research needs to establish a procedure to quantify the remaining structural performance of reclaimed steel considering possible exposure to earthquakes, establish connections that allow for easy disassembly, and introduce modularized structural systems. High seismicity and the general practice to adopt full moment frames pose unique challenges for steel reuse in Japan. [ABSTRACT FROM AUTHOR]

The rapid growth of urban populations and the environmental concerns associated with this growth challenge city planners and developers to consider more sustainable building systems. In Japan, the recent change in the law governing building standards and introduction of cross-laminated timber (CLT) offer the prospect of a further extension of the height of timber buildings to the high-rise category. Because of that, many researchers have begun to research the possibility of hybridizing CLT with steel-framed structures to increase the performance of buildings utilizing CLT. This paper presents the test and numerical results of cyclic loading experiments performed upon CLT shear wall infilled hybrid steel frames with concealed metal plates and drift pin (DP) connections. For the failure modes of the tests, shear failure of CLT at around 1/50–1/30 rad were observed in almost all specimens, except the specimen with slender steel beams, which led the CLT to out-of-plane deformation. The load sharing effect between two components were also evaluated, showing that the steel and CLT infill worked closely together to resist the lateral load. After the experiments, a numerical model was developed using the nonlinear finite analysis software SNAP V7.0 to predict the results of the experiments. The model was developed based on the results of element tests conducted previously, was validated using the test results, and can potentially serve as the basis for an appropriate form of methodology with which to design future CLT-steel hybrid structures for service in seismically active regions. [ABSTRACT FROM AUTHOR]

The deployment of wireless sensor network (WSN) for continuous seismic monitoring system of cable-stayed bridge is presented in this paper. A newly developed WSN that is based on simultaneous high-speed concurrent transmission flooding technique was implemented on the Shin-Nakagawa Bridge, a 530-m single-plane, single-pylon, steel box girder, cable-stayed bridge in Ibaraki prefecture, eastern Japan. The structure is seismically isolated with laminated rubber bearings at the main pylon and piers. Some isolation bearings were partially damaged by the 2011 Great East Japan (Tohoku) earthquake. As a part of monitoring, a WSN with a total of 26 sensor nodes were installed at several locations on the piers, main pylon, girder, and ground. This paper describes the WSN system, the monitoring scheme and procedure, analysis of recorded seismic responses, and their use for structural assessment, especially the performance of isolation bearings during earthquakes. The monitoring system successfully recorded structural responses from 63 earthquakes in the 45 months monitoring period between August 2017 to December 2020, which include the responses from near-field and far-field earthquakes. The comparisons of recorded ground motions with existing nearby seismograph have shown the accuracy and reliability of the WSN. Modal parameters of the bridge were successfully determined from the seismic responses obtained from the WSN using multi-input multi-output time-domain system identifications. Characteristics of seismically isolated bridge responses, such as high-frequency filtering effect and decoupling effect of the girder responses, can be clearly observed from the records of the large earthquakes. [ABSTRACT FROM AUTHOR]

Compound flood disaster risks are increasing due to multiple river floods within a single storm event. Many studies targeted dependence structure based on multivariate extreme value theory; however, fewer studies focused on the sum of subset joint probabilities (SSJP), defined as the probability that any combination of rivers are flooded over the target area as an integral index of compound flooding risks. Modeling multivariate extremes at high dimensions faces two challenges: model complexity and sample size. In this study, as a classical asymptotic dependence model, the Hüsler–Reiss (HR) model was explored to resolve the former issue owing to its simplicity. From the multivariate HR model, any subset joint probability is explicitly obtained without numerical integration of angular measure, and dependence parameters are constructed from only pairwise parameters. The latter challenge was addressed using a large ensemble (50 members of 60-year simulation) of the database for policy decision-making for future climate change (d4PDF), which is consequently regarded as the annual maximum flow data of 3,000 years. This study analytically derived SSJP based on the HR model and tested its applicability using annual maximum flow data simulated from d4PDF for 20 rivers in Kyushu Island, Japan. The simulated SSJP based on the HR model and empirical SSJP were compared as the probability plot of the number of river basins where peak discharge exceeds the design level. As a result, under the constraint of HR that the partial correlation must range from −1 to 1, the estimated SSJP by the HR model was in agreement with the empirical SSJP. The case study presents promising results of the proposed HR model–based approach. [ABSTRACT FROM AUTHOR]

The stability of slopes subjected to vertical embedded strip footing loads under static and seismic conditions was investigated. The pseudostatic method was considered to represent an earthquake load. Two-dimensional lower-bound finite-element limit analysis (LB-FELA) and the strength reduction method (SRM) were employed to investigate the stability and failure mechanisms of the slopes subjected to the footing loads. It was found that the factor of safety (FOS) started to decrease rapidly after a certain load (defined as a threshold load). The critical location of the footing on the slope (where the FOS was at a minimum) was examined. In addition, a series of numerical analyses were carried out to check the effect of edge distance on slope stability. Changes in the FOS were evaluated for a particular footing edge distance for varying slope angles. The effects of variation in the shear strength parameters and the location of the water table on the slope stability under footing loads were also examined. It was found that the effect of loading intensity on the FOS was significant for gentle slopes, with this effect decreasing for steeper slopes. The influence of footing width on the FOS, for a given slope angle and loading intensity, was also insignificant. The footing near the slip surface at the top of the slope was the most critical location. The effect of the water table on the FOS diminished as the loading intensity on the footing increased. To demonstrate the practical application of this study, we also examined the slope failure that occurred during the 2011 Tohoku, Japan, earthquake. [ABSTRACT FROM AUTHOR]

Understanding the seismic resistance mechanisms and safety limits of cross-laminated timber (CLT) buildings and performing an accurate evaluation of their seismic performance is critical in earthquake-prone areas such as Japan, the US, and Italy to ensure that human lives are protected against major earthquakes. However, the knowledge from shaking table tests of full-scale CLT buildings is limited, and most tests' maximum interstory drift is less than 4%. As a first step toward collapse analysis, this study replicated a full-scale two-story shake table experiment with a maximum interstory drift of 8.77%. The analysis software was developed by the authors and modified to consider the restoring force and the P–δ effect to replicate seismic behavior at large deformation. The skeleton curve parameters were employed in the analysis model and then changed. The results that matched the experimental results well were searched comprehensively by performing data assimilation. As a result, both the overall behavior (story shear force–interstory drift relationship) and the detailed behavior (uplift displacement of CLT wall foot of the first story) were consistent with the experimental results, indicating that the proposed analytical method can replicate the seismic behavior of CLT buildings even at large deformation. [ABSTRACT FROM AUTHOR]

Urban health efficiency is influenced by both urban planning decisions and the functioning of the public health system. However, there is currently a lack of effective methods to simultaneously examine urban planning and public health when assessing urban health efficiency. This study proposes a two-stage network data envelopment analysis (DEA) model for evaluating urban health efficiency. The urban planning and public health sectors act as interconnected stages where the public facilities and living quality are mediating variables. The urban health efficiencies of 303 Japanese cities are examined using the proposed model, showing that most Japanese cities still have room for urban planning improvement with pure technical efficiency ranging between 0.7 and 0.9. At the same time, most public health sectors of Japanese cities reach pure technical efficiencies larger than 0.95 but are limited by the scale efficiency. Further analysis points out that public health sectors are in decreasing-return-to-scale, meaning that excessive urban scale adversely affects urban health efficiency. Furthermore, cities that joined the Alliance for Healthy Cities (AFHC) performed better on average, suggesting that information sharing and national and international networking can boost urban health. The study shows that the proposed two-stage network DEA model can be applied to analyze urban health efficiency and identify the impact of technology and urban scale in different stages. [ABSTRACT FROM AUTHOR]

To present a hybrid theory of disaster prevention actions and develop a common framework, this study theoretically and systematically reviewed recent research in Japan on actions from three perspectives: definition, multidisciplinarity, and multidimensionality. First, this research validated that the definition of actions on disaster prevention and reduction should be understood in three contexts: responsibility, willingness, and habituation; the diversity of terminology; and the type of measure. Second, the multidisciplinary nature of the approach affirmed that the motivations and approaches could be organized according to the axes of individual and social models and epistemic and design sciences. Third, per the multidimensional nature of theories explaining actions, the applied theories were organized based on the four perspectives: process, motivation, internal experience, and context. Furthermore, it was suggested that there are three critical perspectives: complicity in neoliberalism, invisibility of social inequalities, and bias in reporting desirable results (expert-serving bias). Taking an approach that emphasizes interdisciplinarity and multidimensionality, this study details the background of Japanese research used to employ a theoretical approach to understand individual cognition and demonstrates the need for research to understand the political, cultural, social, and economic environments that support disaster prevention behavior, noting that this is tied to the unique Japanese context of individual will and dependence on the government. This study is significant in that it provides a map for positioning one's research and pointing the way toward future collaboration in the direction showing definition, interdisciplinarity, and multidimensionality are important components in understanding disaster prevention behavior. This study reviewed three aspects of recent disaster research in Japan to better understand disaster prevention behavior: what it is and what areas and aspects of it are being studied. First, Japanese disaster prevention behavior can be understood in relation to "responsibility," "will," and "habit"; the diversity of behaviors; and the types of measures applied. Second, motivations and approaches could be amenable to organization along the axes of whether the coping subject is an individual or society and whether the science focuses on "what it is" or "what it can do." Third, explanations of disaster prevention behaviors were found to be viewable in relation to four perspectives: process, motivation, experience, and context. Three criticisms were also found: social inequalities are less visible, many results that are preferable to the researcher are reported, and there is a risk of becoming connected to particular political policies. This study found that although many theories that explain individuals' perceptions are used to explain their disaster prevention behavior, it is also important to understand the environment of the political, cultural, social, and economic aspects that surround the individual. [ABSTRACT FROM AUTHOR]

There is increasing interest in using cross-laminated timber (CLT) in buildings because of its high strength and stiffness. In Japan, structural design guidelines for CLT buildings were established in 2016 and construction of mid-rise buildings is increasing. Wide-panel walls can exceed widths of 10 m and integrate cut-outs for window and door openings. However, under lateral loads, corner cracks at the openings have been the most prevalent failure mechanism. To investigate the initiation and propagation of corner cracks, a series of bendings are undertaken on L- and T-shape specimens extracted from the CLT panels. In addition, three-point bending and shear tests are also carried out on beam sections extracted from the CLT panels. Three types of brittle failure were observed: bending failure of the beam or column, and rolling shear failure. [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]

Six full-scale specimens were tested to examine the cyclic-loading performance of steel moment connections between an I-section beam and I-section column. The specimens represented the current practice in Japan in materials, dimensions, detailing, and fabrication. Three of the specimens had the beam welded to the web of the column; the other three had the beam welded to the flange of the column. Some of the specimens had doubler plates welded to the column web. Regardless of the framing orientation, the specimens displayed similar strength and stiffness. All specimens met the performance requirement for special moment frames according to US seismic provisions except for one specimen, which had the beam welded to the column web, and which failed prematurely by fracture of the continuity plate. Yielding of the continuity plate was found to be an important factor that can lead to such failure. Therefore, by making the continuity plates stronger than the beam flanges, either by adopting a sufficiently strong steel or thicker plate, moment connections to the column web, fabricated according to the current Japanese practice, may behave very similarly to moment connections to the column flange. [ABSTRACT FROM AUTHOR]