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In Japan, recently there has been an increase in the failure of dry masonry retaining walls located in an urban residential area due to strong earthquakes. However, currently there are no established optimal seismic reinforcement methods for such dry masonry retaining walls due to issues related to workability and construction cost. This paper presents a novel reinforcement method wherein the tilting reinforcement bars were installed from top of the retaining wall whose individual blocks were integrated. A detailed investigation and discussion on the mechanical behavior of a dry masonry retaining wall is made by comparing the results among different experimental cases which had different seismic reinforcement treatment with the help of tilting table experiments conducted in a geotechnical centrifuge. The results highlighted that the proposed method, the application of tilting reinforcement bars together with the integration of individual wall blocks, led to the best seismic resilient performance of the retaining wall with the least measured soil deformations and soil strains at the backfill. Among all the tested cases, the proposed method resulted in the least mobilization of axial force and bending moment at the top of reinforcement bars which may result in the overall reduction of the construction cost (i.e., by reducing the number of reinforcement bars) aiming toward a performance‐based design. Lastly, an analytical evaluation of the factor of safety (FOS) against collapse as per the Mononobe‐Okabe theory was made which was found to be in excellent agreement with the centrifuge experiments revealing the proposed method to perform best among all the cases. [ABSTRACT FROM AUTHOR]

Increasing the lodging resistance of rice through genetic improvement has been an important target in breeding. To further enhance the lodging resistance of high-yielding rice varieties amidst climate change, it is necessary to not only shorten culms but strengthen them as well. A landrace rice variety, Omachi, which was established more than 100 years ago, has the largest culm diameter and bending moment at breaking in the basal internodes among 135 temperate japonica accessions. Using unused alleles in such a landrace is an effective way to strengthen the culm. In this study, we performed quantitative trait locus (QTL) analysis to identify the genetic factors of culm strength of Omachi using recombinant inbred lines (RILs) derived from a cross between Omachi and Koshihikari, a standard variety in Japan. We identified three QTLs for the culm diameter of the 5th internode on chromosomes 3 (qCD3) and 7 (qCD7-1, qCD7-2). Among them, qCD7-2 was verified by QTL analysis using the F2 population derived from a cross between one of the RILs and Koshihikari. RNA-seq analysis of shoot apex raised 10 candidate genes underlying the region of qCD7-2. The increase in culm strength by accumulating Omachi alleles of qCD3, qCD7-1 and qCD7-2 was 25.0% in 2020. These QTLs for culm diameter pleiotropically increased spikelet number per panicle but did not affect days to heading or culm length. These results suggest that the Omachi alleles of qCD3, qCD7-1 and qCD7-2 are useful for breeding to increase lodging resistance and yield. [ABSTRACT FROM AUTHOR]

The present study assessed the Bailey Bridge's condition and investigated its adaptation as a permanent structure, targeted the Acrow Bailey Bridge in Japan. Field diagnostic loading experiments were performed under various loading conditions, such as dynamic and static loading tests. The onsite data were obtained using a transducer, friction strain gauge, target measurements for the image processing approach, and accelerometer. From the field measurements, the deflection and stresses of the bridge were found to operate within the linear elastic region. The bridge was then accurately modeled based on the in situ geometric configuration of the bridge, and Finite Element Analysis was performed. The model's accuracy was validated with the onsite data under the linear elastic domain. The model was deployed to check for resistance of critical members. A nonlinear analysis based on the linear and nonlinear buckling method was performed to determine the subject bridge's Serviceability Limit State and Ultimate Limit State. The results showed that the first out-of-plane eigenvalue buckling analysis could monolithically assess bridge members. Further, the study established digital twin models resolve for historical data through in situ modeling measurements. Therefore, the findings obtained in this study highlight the bridge's Structural Health Condition, bearing capacity, and propose a framework for adaptation as a permanent structure. [ABSTRACT FROM AUTHOR]

The square hollow section (SHS) is commonly used for the column of the steel building structures in Japan. The moment‐resisting frame will resist the lateral force with the flexural manner of the columns. Under the seismic event, the bending moment will be significant, and the plastic hinge may be formed in the columns. It is crucial to understand the structural behavior at the component level to capture the structure system's ultimate limit state by computational simulation. Understanding the strength and the ductility is one of the essential aspects, but it is also crucial to know the structural elasto‐plastic behavior until the ultimate limit state. It is worthwhile to conduct the testing of the members under combined loading conditions. In this paper, the test results obtained from the different width‐thickness ratio SHS were reported. The forces subjected to the specimen were axial force and cyclic bending moment; therefore, the member was under combined loading condition. Collapse mode, maximum bending moment, and plastic deformation capacity were evaluated in consideration of the effect of the width‐thickness ratio; comparison study between the current design recommendation was also shown. [ABSTRACT FROM AUTHOR]

In Japan, the steel‐concrete composite girder bridge is widely used to reduce construction and maintenance cost, and improve constructability and the construction period. As an effort to decrease box girder construction cost, the narrow box girder bridge, which has a reduced box girder width, has been developed. Compared with a conventional box girder bridge, this type of box girder bridge simplifies the structure inside the box by narrowing the space between web plates. Furthermore, it is possible to reduce the number of members, welding length and painting area. The average economical span length is approximately 90m. Similarly, in European countries, a new type of composite girder bridge was developed and constructed for the same purpose as the bridge in Japan. The steel‐concrete double composite girder bridge, which has two concrete slabs on the upper and lower surfaces of the girder only in the region of the intermediate supports, is a type of medium span bridge. An advantage of adopting this structural system is that the cross sections of both the sagging and hogging bending moment areas are classified into the compact section at the ultimate limit state; that is, the maximum flexural strength of these sections can be taken full plastic moment. There are few constructed examples of this type of bridge in Japan. Because of the handling difficulty, the shop manufacturing cost of a box girder is, generally, more expensive than that of an I‐girder. Additionally, the design method for bridges has been revised since January 2018 and has changed from the allowable stress design method to the limit state design method in Japan. Therefore, the authors propose a new type of steel‐concrete double composite I‐girder bridge. The trial design of three‐span continuous girder bridges was conducted. In this paper, the effect of double composite action, for instance, the reduction of the girder height in the region of the intermediate supports, and applicable span length are discussed. [ABSTRACT FROM AUTHOR]

The design formulae of beam‐column are provided by Recommendation for Limit State Design of Steel Structures (LSD) in Japan. The design recommendation shown in LSD is derived from the test results that are basically obtained from one end monotonic bending moment. Therefore, it is necessary to examine whether these formulae can appropriately evaluate the strength of the beam‐column under cyclic loading condition. In this paper, the test results of the deep‐column are reported. The dimensions of the specimens were determined per LSD. Deep wide‐flange section H‐150×75×5×7 (unit: mm) is used for the specimen. From the testing, a few unconservative results were observed in LSD design formulae. [ABSTRACT FROM AUTHOR]

• Shaking table model tests were conducted to examine seismic behavior of THMA culvert. • The embankment sequences significantly affect the deformation mode of THMA culvert. • The culvert exhibits alternative left and right bias deformation in dry sand case. • Simultaneous backfilling on all sides of the THMA culvert is the safest sequence. A three-hinged multi-arch (THMA) culvert is a new type of underground structure that is gradually being adopted in practical engineering in Japan as an alternative to elevated bridges. However, there exist reports that THMA culverts were seriously damaged by earthquakes in the past, and research on the behavior of THMA culverts during the embankment process and exposure to post-construction earthquakes is insufficient. Therefore, to carefully investigate the static/seismic mechanical behavior of the THMA culvert, systematic 1 g shaking table model tests were carried out in the current study. THMA culverts were constructed using different embankment procedures in dry/saturated sand ground, and then subjected to seismic loading. The results showed that the different embankment procedures significantly affect the deformation mode of the multi-arch culvert on both dry and wet sand grounds, and the construction sequence involving simultaneous backfilling on both sides of the culvert can reduce the generated bending moments during seismic vibration. Furthermore, in all cases, the bending moments generated during the earthquake were significant on both sidewalls of the culvert in the range of 30°–60° from the ground, and the bending moments in the region near the hinges were smaller, which provided basic data for the optimized design of the culvert. [ABSTRACT FROM AUTHOR]

The effects on Robinia pseudoacacia (an exotic and invasive plant in Japanese rivers) of local scouring and saturation of the soil in the root-anchoring zone due to flooding were investigated. Scouring has been defined as the removal of substrate in the root-anchoring zone, exposing the tree roots. Tree-pulling experiments were conducted, simulating flood action, and the resulting damage was examined in order to assess the effect of local scouring on the maximum resistive bending moment ( M) for overturning. Scouring was artificially created to three different depths, 0, 25, and 50 cm. A nonlinear model was developed that included soil strength characteristics to calculate the critical overturning moment ( M) under dry and saturated soil conditions. Significant correlations ( p < 0.05) of M with different tree and root-soil plate characteristics, such as diameter at breast height ( D), tree weight, root depth, and root-soil plate radius, were developed in order to elucidate the effects of scouring on M. M was slightly reduced with scouring depth for trees with D <10 cm (small) trunks, and it was significantly and negatively ( p < 0.05) correlated with scouring depth for trees with 10 < D < 20 cm (medium) trunks. However, M did not change significantly with scouring depth for trees with a D >20 cm (big) trunks. The nonlinear model was useful for determining the M of R. pseudoacacia under dry and saturated soil conditions. The overturning moments of all (small, medium, and big) trees were considerably reduced under the saturated soil condition. It could be concluded that medium-sized trees were greatly affected by scouring, and that small and big trees were mainly affected by saturation of the soil under severe flooding conditions. [ABSTRACT FROM AUTHOR]

Abstract: Damage to embankments and forests along the coast of the northeast Japan by the 2011 Great East Japan tsunami was observed at twenty-five locations covering a length of about 340km. A modified two-dimensional depth-integrated shallow water model was applied to analyze the tsunami mitigation by the artificial and natural structures at two coastal sites: Misawa, a site with vegetated dune, and Hachinohe, a site with seawall and coastal vegetation. In addition to configuration of the real sites, a few hypothetical cases were tested with alternative arrangements of these structures to identify their contribution towards tsunami mitigation. The numerical results revealed that the vegetated dune in Misawa was the primary reason for the mitigation of the tsunami and that the shape of access roads (straight or crooked) through the vegetation to the coast had a great effect on the variation of flow velocity increment compared to in the absence of vegetation. An asymmetry in the damage to the vegetation was observed at Hachinohe, where the vegetation behind the seawall was undamaged and the vegetation that was not shielded from the seawall was damaged. The simulation results showed that diversion of the tsunami flow by the seawall supported creation of a higher moment (4–2kNm) of the vegetation compared to the places behind the seawall (less than 0.2kNm). The actual flow velocity and Froude number of the wave front at the Sendai Plain were calculated from video footage. The average flow velocity 1km inland was 6.2m/s, and the corresponding Froude number was ca. 1.14–1.4. The values are comparable with the maximum Froude number at the time the tsunami hit the shore at Misawa and Hachinohe, which was determined by the modeling to be ca. 1.5. [Copyright &y& Elsevier]

Effects of root architecture, physical tree characteristics, and soil shear strength on overturning moment due to flooding were investigated using Salix babylonica and Juglans ailanthifolia, exotic and invasive plants in Japanese rivers. Tree-pulling experiments that simulated flood action were conducted, and the resulting damage was examined to assess the effects of physical tree characteristics and root architecture on the maximum resistive bending moment ( M) for overturning. In situ soil shear strength tests were conducted to measure soil strength parameters. The effects of species differences on the M were examined by analyzing root architecture. S. babylonica has a heart-root system that produces a greater overturning moment due to the strong root anchorage and the large amount of substrate that must be mobilized during overturning. J. ailanthifolia has a plate-root system that produces a smaller overturning moment. However, trees with the plate-root system may withstand overturning better due to an increased root:shoot ratio. The results of the study show that the M of a tree for overturning had significant ( P < 0.05) correlations with a tree's physical characteristics, including height ( H), trunk diameter at breast height ( D), D, height multiplied by the second power of D (trunk volume index H × D), and root-soil plate depth ( R), and root-soil plate radius ( R). Considering the strategy of J. ailanthifolia to increase the root:shoot ratio for anchoring in the substrate, the trunk volume index ( H × D) is a better parameter than D because it indirectly involves the difference in below-ground volume and surface area. Different soil cohesion values were found at different experimental sites, and the average M for overturning each species decreased linearly with increasing soil cohesion. [ABSTRACT FROM AUTHOR]

• Numerical model which can consider elastoplastic behavior of panel zone of beam–column connection under multi-directional loadings. • Numerical model for 3D steel moment frame that comprised H-shaped beams, square hollow section columns and panels. • Comparison between loading test of cruciform frames and analysis results of proposed numerical model. • Time history response analysis of 3D steel moment frames under bidirectional ground motions. • Influence of strength ratios between structural members on energy dissipated from the plastic deformation of the beams, columns, and panels within each beam–column connection. In Japan, steel moment frames comprising H-shaped beams and square hollow-section columns with through diaphragms are often used for low- to middle-rise building structures. The column overdesign factor—strength ratio between columns and beams—is specified as ≥1.5 in Japanese seismic design code to ensure adequate energy absorption capacity against bidirectional ground motion by achieving an entire beam-hinging collapse mechanism. However, the required column overdesign factor of steel moment frames is obtained from analysis results conducted under unidirectional ground motions. Additionally, the numerical models of most previous studies considered the behavior of only beams and columns, and ignored the behavior of the panel zone of the beam–column connection. Nevertheless, the panel zone may yield with the beams and columns under severe earthquakes. In addition, the influence of panels on steel moment frames subjected to bidirectional ground motion is not completely understood, as a numerical model for panels under bidirectional shear forces and biaxial bending moments is yet to be proposed. Thus, this research proposes a novel numerical model for studying steel moment frames under multi-directional loadings to consider the 3D elastoplastic behavior of beams and columns, as well as panels. The proposed numerical model was validated by analyzing cruciform subassemblies of beams, columns, and panels, and the analysis results were compared to the experimental results from previous studies. Furthermore, a time-history response analysis was conducted for the 3D steel moment frames, and the energy dissipated from the plastic deformation of the beams, columns, and panels within each beam–column connection was discussed from the aspect of strength ratios between structural members. [ABSTRACT FROM AUTHOR]

• Database of 79 steel-encased precast concrete pile tests collected. • Bending capacity checked by stress distribution and strain compatibility methods. • Validated numerical model includes high-strength concrete and steel pipe buckling. • Model reproduces curvature, moment, drift and hysteresis behavior. • Effect of hollow core on concrete confinement, and buckling are important factors. The use of steel-encased precast concrete (SC) piles has risen rapidly for the construction of earthquake-resilient foundation systems for buildings in Japan and Southeast Asia. SC piles are used near the pile-pile cap connection owing to their increased ductility, and resistance against large bending moments and axial forces, compared to the other precast concrete piles. However, there are no official guidelines available for the design of SC piles in severe earthquakes, except for a proposed draft by the AIJ committee for the determination of bending capacities. In this work, a database of 79 tests on SC piles, all tested under axial-flexural loads, was created. The bending capacities obtained from these tests were used to verify the provisions of the proposed draft and the provisions for composite member design in AIJ, Eurocode 4 and, AISC. Furthermore, a distributed plasticity formulation was adopted to develop a non-linear static model, that takes into account the concrete confinement and local buckling of steel casing, for prediction of moment and drift capacities. The accuracy of the model was verified against various experiments, and the capability to reproduce the moment-drift relations was confirmed. [ABSTRACT FROM AUTHOR]