Hollow-section RC piers, which can reasonably secure bending stiffness, have been widely adopted for high piers in mountainous regions. However, it has been noted that hollow-section RC piers exhibit brittle failure with abrupt axial settlement at limit states, and thus, plasticization is not permitted under current seismic design standards. Consequently, seismic retrofitting of hollow-section RC piers is being actively pursued. However, as retrofitting all existing hollow-section RC piers would require considerable time, it is necessary to appropriately assess the prioritization of the seismic retrofitting. In this paper, a new limit state for hollow-section RC piers is defined by focusing on the position of the neutral axis in the cross section, and a method for determining the priority of seismic retrofitting based on this limit state is proposed. The results show that the proposed limit state offers high reliability in evaluating the ultimate displacement of hollow-section RC piers, where the axial settlement of column occur, and it could serve as an indicator for developing rational seismic retrofitting plans for existing hollow-section RC piers.

 Steel members in bridges that have been in service for a long time may lose sufficient load-carrying capacity due to corrosion. One of the countermeasures is the use of stainless steel, corrosion-resistant steel. However, there is little information regarding the load-carrying capacity of steel members made of stainless steel. This study focuses on the load-carrying capacity of outstanding plates made of SUS323L, a type of stainless steel. Axial compression tests were conducted using four cruciform section stub-columns with different width-to-thickness ratio parameters. Further information on load-carrying capacity was collected by means of parametric analysis. The validity of the analysis method was confirmed through reproduction analysis. Based on the both experiment and analysis results, more rational formulas for the load-carrying capacity of outstanding plates made of SUS323L were proposed.

 In 2020, CHIDA et al. conducted FEM analyses to simulate the situation that forced displacement due to ground deformation acted arch ribs of upper-deck type arch bridge, and yielding occurred at the arch crown by 10 or more cm forced displacement for bridge axis direction. Four years later, during the Noto Peninsula Earthquake of 2024, the abutment of upper-deck type steel arch bridge slid in the direction of the side span and buckled at the arch crown. This study confirmed the high accuracy of the FEM analysis that simulated the behavior caused by ground deformation and the vulnerability of bridges composed of bearing members to ground deformation. In this study, the relationship between the number of span and damage behavior was compared by simulating the forced displacement of the lower chords due to ground movement in 4 to 8spans warren truss bridge which consists of bearing members in the same way as arch bridge, and to formulate the amount of forced displacement that can cause damage to the bottom chord material.

 The authors have examined the residual seismic performance of RC piers through cyclic loading experiments, referencing the limit state defined in the Highway Bridge Specifications. A dynamic earthquake response analysis was conducted on the test specimen by reducing its stiffness using the proposed formula. Additionally, a static earthquake response experiment was performed, in which the obtained response displacement was applied to the actual test specimen at a constant speed. The purpose of this experiment is to investigate whether the proposed formula for predicting equivalent stiffness can be applied to earthquake responses that exhibit greater variation in the balance of positive and negative amplitude displacements and the number of repetitions compared to the alternating cyclic loading experiments, as well as to assess the applicability of the proposed formula in dynamic earthquake response analysis. The findings from the static earthquake response experiment are reported. Furthermore, since the response displacement when the stiffness is reduced using the proposed formula may exceed twice that of the unmodified stiffness, the calculation formula proposed in this study facilitates an examination in accordance with anti-catastrophe considerations, taking into account multiple earthquake actions in the seismic performance verification based on the skeleton curve of the load-displacement relationship of RC piers. The reduction rate of equivalent stiffness for the second loading in this experiment, compared to the first loading, was generally consistent with the reduction rate of equivalent stiffness calculated using the authors' proposed formula. This indicates that the model of the skeleton curve of the load-displacement relationship based on this formula is valid within a certain range, even under random and pulsive loading histories.

 The addition of bars through the wall is necessary for seismic reinforcement of wall-type piers, but there are challenges in its construction. Therefore, we have devised a retrofitting method with buckling-restrained rebar instead of added axial reinforcement of the RC jacketing retrofitting method as a structure that can secure deformation performance even if the added bars through the wall is omitted. A buckling-restrained rebar is a longitudinal reinforcing bar covered with a steel pipe. This paper presents a design method developed from horizontal cyclic loading experiments of seismic reinforcement structures for wall-type piers using buckling-restrained rebars as previously reported.

 In the Noto Peninsula earthquake that occurred on January 1, 2024, several ruptures of laminated rubber bearings were confirmed. The functional evaluation of rubber bearings in the current handbook for road bridge bearings and Specifications for highway bridges was not based on fracture, and it was recognized that there is a need to establish new regulations based on the state of fracture. However, it is difficult to conduct fracture tests on full-scale specimens, and FEM analysis has attracted much attention. In this study, FEM analyses was conducted to verify the internal stress state in the full-scale laminated rubber bearing under horizontal shear strain. The cause and mechanism of bending deformation in the inner steel plate were clarified, and the deformation and stress distribution in the rubber material, adhesive layer, and inner steel plate were clarified. It was also shown that the dominant stresses in the rubber material and adhesive layer are not shear stresses but maximum principal stresses and equivalent stresses.

 In evaluating the seismic performance of columnar attached structures installed on bridges, the sensitivity to resonance will differ depending on the amount of plasticity of the bridge. Due to the natural period shift caused by yielding, the response of the columnar structure can be decreased as the ground motion input increases. In this study, using a TV pole installed on a bridge pier as an example, the relationship between the input ground motion intensity and the dynamic response amplitude of the TV poles is investigated by means of the incremental dynamic analysis (IDA), focusing on the possibility of unconservative seismic response assessment using nonlinear time history analysis. As a result, it was confirmed that for the target structure and input waves, when the bridge pier becomes significantly plastic and the natural period becomes long, the relationship between the magnitude of the input earthquake motion and the response of the TV pole is reversed.

 The 2024 Noto Peninsula earthquake damaged several roadway structures. In the upper deck steel arch bridges that the authors surveyed for earthquake damage, buckling of the members near the crowns of the arch ribs was observed. Based on the results of the earthquake damage survey, the possibility of lateral movement of the A1 abutment was identified, and axial forces introduced into the arch ribs due to this movement were inferred to be the primary cause of the member buckling. Since the bridge was constructed in an old age and no drawings were available, an analytical model was created from the point cloud measured by LiDAR. The LiDAR used for the measurement was not accurate enough to measure the cross-section of the member, such as its thickness, and the cross-section was determined based on the results of the field measurements and the restored design. In this paper, we report the results of damage estimation for the analytical model considering various load actions and analytical investigation of damage factors of member buckling, and also the results of earthquake damage survey.

 Water pipelines are typically buried underground, but at locations where they cross rivers, they are constructed as water pipe bridges. The 2024 Noto Peninsula Earthquake significantly damaged the ground behind bridge abutments, affecting many water pipe bridges. Bellows-type expansion joints, installed to absorb pipeline displacement, exhibit large deformation modes due to ground deformation. However, the current bellows design methods are based on fatigue design for cyclic displacement and the critical displacement for large deformation modes has not been defined. This study conducted displacement loading experiments on bellows-type expansion joints to investigate the critical displacement under large deformation modes. The experimental results indicated that the critical displacement for water pipe bridge design can be determined by the geometric dimensions of the bellows.

 Since the Hyogo-ken Nanbu Earthquake, laminated rubber bearings have been actively used. Several decades have passed since their installation, and ruptures have been reported in the Tohoku Pacific Offshore Earthquake, the Kumamoto Earthquake, and the Noto Peninsula Earthquake. The authors have been evaluating the damage to rubber bearings using the AE method, a non-destructive testing method. Historically, AE measurements were performed by applying traffic loads to rubber bearings in service. However, this method does not apply to cases of unexpected traffic vibration. Therefore, we focused on the waveforms obtained from AE measurements of rubber bearings vibrated by a function generator. In this study, we conducted laboratory experiments on rubber bearings with simulated defects and confirmed the frequency characteristics of AE waveforms detected by FFT. Comparing the results of the laboratory experiments with the results of field measurements of the rubber bearings damaged in the 2024 Noto Peninsula Earthquake, it was confirmed that there was a correlation in the frequency components of the Fourier spectrum.

 Rocking seismic isolation is an isolation structure that actively utilizes the isolation effect caused by uplift of the foundation. The aim of this study was to clarify the seismic response characteristics of bridges that apply rocking seismic isolation based on shaking table tests using a bridge model which simulates the entire bridge system. In addition, a reproducible analysis of the shaking table tests was performed utilizing an earthquake response analysis using a discrete frame structure model. Results showed that rocking seismic isolation functions were effectively even in a bridge with two piers, with a significant reduction in the maximum bending moment at the base of the pier due to the isolation effect, and that the analytical model was able to predict the maximum value of the bending moment, but that it underestimated the maximum value of the girder response displacement.

 Since the 1995 Great Hanshin Earthquake, the use of laminated rubber bearings has been increasing because of their high deformation capacity and their ability to cushion and transmit impact forces such as seismic forces through the rubber body itself. These laminated rubber bearings must maintain their performance even when level 2 earthquake motion is dominant, so it is important to understand the mechanical performance of the laminated rubber bearings in their ultimate state. In this study, a rubber bearing was subjected to a sufficient number of cyclic cycles of 175 % shear strain before being loaded at 250%, 175%, and 300% in sequence at actual velocity (about two second in period). During, the sliding behavior of the jig and the accompanying collision between the jig and the member occurred during the 300% excitation. We investigated the collision mechanism and estimated the impact coefficient.

 In quality control for laminated rubber bearings used in road bridges, verification tests are conducted on 240mm and 400mm bearings to evaluate their mechanical capacity. On the other hand, due to the limitations of loading capacity of the testing machine, it has been difficult to conduct experiments at full-scale and full-speed in the past. Since in 2023, a full-scale seismic isolation testing facility (E-Isolation) was installed, making it possible to conduct full-scale, full-speed testing in Japan. In this study, we used that testing machine to confirm the effects of large strain cyclic shear deformation on the characteristics of full-scale laminated rubber bearings. The results showed that the number of cycles, the period (velocity), temperature, and loading interval all had an effect on the stiffness and damping coefficient, and also showed the relative magnitude of the effect of each of these factors on the stiffness and damping coefficient.

 Rubber bearings, which are used to improve the seismic performance of road bridges, have dependencies such as cyclic dependence and temperature dependence. In particular, the stiffness is expected to increase at low temperatures. Therefore, the authors proposed an empirical correction formula to account for the effect of low temperatures.

 However, due to limitations of bearing test system, the results were obtained only for a plane dimension of 250 mm, and the effect of low temperature on the dimensional effect has not been fully discussed.

 In this study, a full-scale shear load test using a cooled rubber bearing was conducted using Japan’s first full-scale seismic isolation bearing dynamic test system, which began operating in 2023. The experimental results were used to examine the relationship between the internal temperature and equivalent stiffness of the rubber bearing, and the change in internal temperature due to shear displacement.

 Beam-to-column connections of steel rigid frame piers affect the seismic performance of piers, so it is important that they have strength and ductility. On the other hand, the beam-to-column connections of steel bridge piers made of SBHS500 is expected to be reasonably designed in terms of thickness reduction and weldability. However, there are few research data on elasto-plastic behavior of beam-to-column connections of steel bridge piers made of SBHS500. In this study, cyclic loading experiments of beam-to-column connections of steel bridge piers made of SBHS500 and SM490Y were carried out in order to investigate the influence of steel type on the elasto-plastic behavior of beam-to-column connections of steel bridge piers. In addition, it was assumed that beam-to-column connections of steel bridge piers made of SBHS500 with a high yield ratio might have inferior strength and ductility. Therefore, the same experiment was conducted on a specimen with a higher longitudinal rib stiffness ratio as an improvement measure.

 The results showed that the strength and ductility of SM490Y tended to be higher than those of SBHS500. And the increase in the longitudinal rib stiffness ratio was effective in mitigating the load drop after the maximum turnaround point.

 In this study, the influence of the trajectory characteristics of bi-directional horizontal seismic input motions on the liquefaction and nonlinear seismic response of sandy soils was evaluated using seismic response analyses with various types of spectrum-compatible waves. The seismic input motion for liquefaction was assessed based on its bi-directional energy spectrum and cumulative displacement. The results of the ground seismic response analysis indicated that the excess pore water pressure ratio was higher for bidirectional inputs than for uni-directional inputs. This confirms the significant influence of the trajectory characteristics of bi-directional horizontal seismic ground motions on sandy soils. Additionally, the calculated bi-directional energy spectrum and cumulative displacement were larger for bi-directional inputs compared to uni-directional inputs, which was consistent with the excess pore water pressure ratio results. Consequently, it is recommended that the seismic input motion for liquefaction should be evaluated in terms of its energy spectrum.

 School sites are often located on valley-filled embankments in elevated areas. Several schools in Ishikawa Prefecture suffered damage due to embankment failures and liquefaction triggered by the 2024 Noto Peninsula Earthquake (M 7.6). The National Institute of Technology, Ishikawa College, situated on a hilltop, was developed by cutting and filling a valley with abundant groundwater due to its topography. This resulted in multiple slope failures and instances of liquefaction. This report analyzes the failure mechanisms based on observed damage at the school site, as well as borehole surveys and soil tests conducted after the earthquake. Additionally, it discusses the secondary damage caused by rainfall in the three months following the earthquake.

 The 2024 Noto Peninsula Earthquake (M_J=7.6) caused widespread liquefaction-induced ground deformation throughout the Noto Peninsula and Hokuriku region, with ground flow due to liquefaction particularly concentrated along the inland edge of the Uchinada Sand Dunes. This report summarizes the characteristics of ground deformation observed in Ohsaki, Kahoku City, including the topographic features of the initiation and convergence points of the ground flow areas. The Uchinada Sand Dunes are classified into old new dunes, with the new dunes characterized by low converted N-values and shear wave velocities, and a shallow groundwater level. The grain size distribution of the sand ejected from the ground was found to closely match that of the new dunes. To understand the impact of groundwater distribution differences on liquefaction-induced flow displacement, a residual deformation analysis was conducted. The results indicate that when groundwater is inclined along the surface, the thickness of the liquefied layer in the new dunes increases, with the groundwater gradient significantly amplifying flow deformation, consistent with the observed cracks and upheaval at the site.

 In this study, we evaluated the maximum drift angle of wooden house models using the performance equivalent acceleration response spectrum at earthquake observation sites where the major damage ratio of wooden houses was investigated in the 2024 Noto Peninsula earthquake. In addition, the major damage ratio of wooden houses was calculated based on the distribution of strength by building age and the maximum drift angles. As a result of the analysis, the major damage ratio of wooden buildings was high at earthquake observation points where seismic motion with a period of 1 to 2 seconds was large. Finally, the major damage ratio of wooden houses of all ages was compared with the results of the damage survey.

 This report describes the earthquake damage to a bridge in Hualien, Taiwan, that occurred at 7:58 a.m. on April 3, 2024 (local time), based on a field survey conducted by the authors. The authors visited the affected area from June 24 to 26, 2024, about three months after the earthquake. The intensity of the earthquake ground motions observed in Hualien was above Level 1 and below Level 2 earthquake ground motions as defined in the Japanese Specification for Highway Bridges. The earthquake damage observed on bridges in Hualien included collisions between main girders and displacement limiting devices, failure of wall rails, and the occurrence of steps due to settlement of the soil behind the abutments. In New Taipei City, about 1 km from the epicenter, the misaligned displacement of a steel box girder of an MRT viaduct was observed.

 In this study, with the aim of gaining knowledge to strengthen disaster prevention literacy among elementary and junior high school students, we conducted a questionnaire survey before and after a lecture on the importance of learning about and preparing for earthquakes and tsunamis. Based on the data obtained, we estimated the relationship between “awareness of phenomena during earthquakes and tsunamis”, “assumptions about evacuation behavior during earthquakes”, and “assumptions about response behavior during earthquakes” using a covariance structure analysis with elementary school students and junior high school students as the population. As a result, it was found that “awareness of phenomena during earthquakes and tsunamis” tended to promote the retention of knowledge in both elementary school students and junior high school students. Furthermore, it was found that “awareness of phenomena during earthquakes and tsunamis” tended to have a strong impact on “assumptions about evacuation behavior during earthquakes” in junior high school students.

 This paper presents examples of destruction and damage observed during field surveys of stainless steel rectangular tanks in the 2024 Noto Peninsula earthquake disaster. The causes of the damage and destruction are two completely different types of vibration phenomena caused by the difference in the period of earthquake motion. The first is the sloshing phenomenon caused by long-period earthquake motion, and the second is the bulging phenomenon, which is mainly caused by vibration of the tank structure caused by short-period earthquake motion. Based on this fact, the paper describes the problems and design issues for improving the seismic performance of stainless steel rectangular tanks, and it is determined that there is an urgent need to improve them.