The steel bellows damper is an elasto-plastic hysteretic damper installed between girder end and abutment to reduce damage of the superstructure and substructure. In the past fatigue tests, a low-strength material is applied to reduce stress concentration at the root positions of the bellows but it seems to be difficult to obtain their sufficient installation effects due to their yielding. Then, in this study, additional loading tests are carried out by focusing on the use of a high-strength material to the parts and a zinc aluminum alloy thermal spray to the bellows to enhance fatigue resistance and rust prevention. A mechanical model and fatigue strength evaluation method for bellows-type dampers were also studied.

The rail support conditions vary significantly at each section of the bridge, abutment, and embankment. This leads to problems such as subsidence in the ballast section behind the abutment, unsupported sleepers, and rail uplift behind the abutment or at the bridge edge. Therefore, a quantitatively evaluable model is necessary. This study proposes the non-linear FEM, which can account for variations in rail support conditions and unsupported sleepers. The results calculated by the proposed model are consistent with the rail displacement distribution measured by images from the bridge to the embankment. In addition, parametric study using the proposed model demonstrates that rail support conditions affect the behavior of the rail laid on bridge, abutment, and embankment.

For cable-stayed bridges, which are made up of steel girders and towers, it is important to design them safely against buckling and to understand their ultimate state. Generally, safety against global buckling is ensured by verification using the effective buckling length. However, it is difficult to accurately evaluate the effective buckling length of a complex structure such as a cable-stayed bridge. Therefore, this paper proposes a method to directly verify safety against global buckling using an elastoplastic finite displacement analysis of the entire bridge system, taking into account both geometric nonlinearity and material nonlinearity.

A static cyclic loading test on scaled specimens was conducted to evaluate the limit state of the column joints of steel arch bridges. The specimens were set based on existing arch bridges, and the joints were made by welding and highstrength bolt friction joints. In the experiments, stable load-displacement curves were obtained, and the vertical support force after damage was confirmed. In the experiment of high-strength bolt friction joints, the phenomenon of bolt axial force loss and fracture of bolt hole were confirmed. Also, the experiment was validated by FE analysis modeling the high-strength bolt friction joint.

Transverse load due to flooding drifts the superstructure of bridges and breaks the bearing side blocks, which can be a trigger of bridge washout damage. The transverse load on the side block causes shear forces and bending moments to the connecting bolts of short-connection joint type. However, the load bearing capacities and breaks of the bolts subjected to those forces are not clear, since these bolts are usually not designed to resist the transverse load action.

Then in this study, loading tests of the bolt under shear, shear and bending are carried out. The test results revealed that when shear and bending act simultaneously on the bolt, the thread fails and the greater the bending effect, the lower the ultimate strength and the greater the displacement at failure.

A lightweight and highly rigid shape for a bridge collapse protection bracket was developed using topology optimization. The design was refined for compatibility, manufacturability, and cost-effectiveness, resulting in a commercially viable product. This paper aims to verify the final design, demonstrating a balance between weight reduction and performance. A full-scale product was fabricated using a 3D sand mold layering machine based on the final design, and its performance was validated through experimentation. A comparative analysis with computational results also confirmed the performance and safety of the final design.

In recent years, works to improve existing structures and strengthen their seismic resistance have increased. Pile construction in narrow spaces is constrained by the site and the construction process. Therefore, a construction method of soil-cement composite pile using a mechanical agitator was developed. The purpose of this study is to apply soil-cement composite piles, which have been conventionally designed as temporary structures, to permanent structures. In order to build the design method on the horizontal resistance, a numerical analysis was carried out to simulate a full-scale horizontal loading test, and the modeling was discussed.

This study proposes a method to suppress reduction in the bearing capacity of the base metal due to hole pulling when repaired by patch plates thickness-reduced plate. For this purpose, uniaxial tensile tests and finite element analyses were carried out to evaluate different bolt types and bolt arrangements in the first row from the loading position. As a result, the fracture resistance of the model with a larger cross-sectional area of the base metal at the position of the first row of bolts from the loading position was higher. The results also showed axial forces at the sectional defects were similar for different bolt types and bolt arrangements.

Not many cases, but there have been reports of damage of roller bearing in existing curved bridges due to external forces applied during normal operation and earthquakes. Now that a few studies have focused on load carrying behaviors of the roller bearings, then in this study, the design trend of bearing arrangements for the curved bridges and the actual uses in Kumamoto Prefecture were investigated. Analytical results of the roller bearings, subjected to increasing horizontal force in arbitrary direction, show that the acting direction of the horizontal force and the deformation behavior need to be evaluated precisely, especially after the rollers and shear keys are in contact condition.

The number of aging bridges in Japan is on the rise, prompting a growing trend in research focused on predicting the load-carrying capacity of bridges using 3D FEM. However, when modeling steel bridges with 3D FEM, modeling of secondary members, such as lateral bracing and sway bracing, varies depending on analysts. The effect of different modeling of secondary members on the analytical results is not clear. Then in this paper, the effect of secondary member modeling on analytical results were investigated in FEM, with focusing on end sway bracings. It is identified that influential modeling methods for evaluating the elastic and ultimate behavior of the horizontally loaded end sway bracing structures.

Stainless steel is a high-performance steel with superior corrosion resistance compared to carbon steel. Applying stainless steel to I-girder ends or lower parts may improve corroded durability. This study examined the compressive ultimate strength of cruciform columns welded stainless and carbon steel through a loading test and finite element analysis. As a result, the compressive ultimate strength of hybrid cruciform columns and outstanding plates can be assessed using a design equation for homogeneous members by a compressive ultimate strength curve proposed in Japan.

Carried out dynamic analysis as a countermeasure for a large earthquake, stress of some main members in a steel truss bridge are exceeded these yield stress. We make these members reinforced by using bolted cover plates to improve member resistance. However, regarding this reinforcement, it is not clearly regulated. And the mechanism of stress transfer of the reinforcement using a bypass device especially under the tensile load is not obvious enough. Therefore, assuming design conditions for such as required numbers of bolts to transfer stresses between base plate, cover plate and bypass device, FEM analysis by using models designed these conditions is carried out by noticing load conditions and some structural forms of bypass device. It is concluded that the mechanism of stress transfer is obvious.

In this study, the effects of bridge vibration on constructing an image-based point cloud have been investigated fundamentally, focusing on the fact that bridges con-stantly vibrate due to external forces such as traffic and wind. A 3D point cloud is expected to be used to construct FE models and to obtain detailed models in line with the current state of structures, yet the vibration of a target is not considered when constructing the point cloud data. In this study, in image-based point cloud construction, where the target needs to be photographed from various distances and angles, bridge vibration is acquired by video analysis, and an attempt is made to construct 3D point cloud data that reduces the effect of vibration at each photo-graphed position by using reference position frames.

When honeycomb sandwich panels are used for bridge webs, we must consider the situation where the panel is loaded in the plane direction and supported on all edges. However, buckling load of the honeycomb sandwich panels are not clear. Therefore, we conducted a lot of the finite element analysis together with parametric modeling method. As a result, it was found that the buckling load of the honeycomb panel is large when the overall buckling mode occurs. The buckling modes are divided into four regions depending on the panel geometry. The buckling load is 50% to 80% of the buckling load of a solid medium flat plate of equal thickness.

Infrastructure management and its extending service life in the area are crucial for the local government to realize the region's sustainability. As part of appropriate maintenance and management, a periodic close-up visual inspection of bridges has been mandatory since 2014 in Japan, and the inspection results have been accumulated. In this study, we proposed a simple conversion method for two inspections with different evaluation methods for the Bridge Health Index, examined its validity, and compared the value of the entire bridge with the evaluation results for each member. From these results, the key point for effectively using bridge inspection records is comparing the evaluation results for each member and each inspection item of damage.

This paper describes the results of a study on a model that can be applied in actual design to evaluate the response behavior of the entire steel girder bridge, including lateral bracings and sway bracings. A space frame model based on beam elements such as floor slabs, girders, bracings is presented, and comparison with a horizontal loading test on the actual bridge shows the response of bracings can be evaluated with good accuracy. In addition, the presented model demonstrates the possibility of simplified and more rational design that takes three-dimensional behavior into account, in contrast to conventional design.

This study focuses on the seismic safety of entire bridge structures and proposes a generalized safety evaluation method based on high-precision numerical analysis. The applicability of the proposed method is demonstrated through a case study involving an upper-deck steel arch bridge, showing that the current numerical analysis techniques can accommodate this approach. The method provides objective information for evaluating the seismic safety of bridges, particularly when the ultimate behavior characteristics of the structure under earthquake conditions are not well understood.

In this study, we investigated reinforcement methods to improve plastic deformability after brace buckling for the end columns of deck arch bridges. To confirm the difference in ultimate behavior with and without reinforcement, cyclic loading experiments were conducted using half-size specimens. We found that restraining the joints at the bottom ends of the brace materials can suppress the decrease in load after the peak. An analysis was performed using a full model to verify the effect of reinforcement on the behavior of the entire arch bridge.

A study was conducted to understand how the smoothness of the skeleton curve before a structure yield affects its seismic response. The bulging of the skeleton curve was represented using the ratio of initial stiffness in a bilinear model, followed by numerous nonlinear dynamic analyses. The results showed that for ductility µ = 1, the ratio of the required demand yield seismic coefficient drops below 1 when the structure's natural period Teq is short, reducing seismic response values. Applying these insights to seismic response calculations is expected to improve accuracy, particularly in assessing structures around yielding, such as during Level 1 earthquakes or post-earthquake evaluations.

In this study, we evaluated the simultaneous effect of flexural displacement and earthquake on steel pipe sheet pile foundations. First, the required performance of bridge under the simultaneous effect of flexural displacement and earthquake was set. And then, the effect of earthquake was determined using 2D FLIP with a bridge-foundation-soil model. Based on the above results, the steel pipe sheet pile foundations were verified by three-dimensional framework analysis, and it was confirmed that there was no safety problem.

This study develops a cable tension monitoring system that uses vibration power generation technology. The system uses vibration power generation technology to generate electricity from the vibration of cables caused by vehicle movement on an actual extradosed bridge. The power is used to transmit tension data calculated from the vibration frequency. The analytical model was used to determine which cables should be tuned to which dominant vibration frequencies. In addition, measurements of the cables were conducted on the bridge to investigate the amount of power generated by the vibration. It was found that LoRa communication is possible by tuning to the dominant vibration frequency of the cable, which vibrates strongly when a truck is moving.

In the official truck platooning tests, three trucks with the back two unmanned successfully ran at a speed of 80 km/h with vehicular gap of 9 m. When multiple trucks move on a bridge at a certain distance between vehicles, large bridge vibration occurs due to the coupled vibration of the vehicles and the bridge. In the case of continuous bridges, there are many vibration frequencies of multiple bridges in close range. Consequently, it is expected that a lot of coupled vibrations between trucks and bridges will be generated. Therefore, this study examined how bridge vibration changes when the vehicular gap is varied through truck platooning tests and vehicle running simulations.

In this study, wind tunnel tests, i.e., pressure measurement tests and Particle Image Velocimetry (PIV) tests, were conducted on two rectangular cylinders with a side ratio of 5 in a parallel arrangement to investigate the effect of their relative distance on the flow field and the pressure distribution around them. Both results of the abovementioned tests indicate that the flow field of the upstream cylinder was like that of a single one and barely affected by the downstream one, while the separated shear layer of the downstream cylinder was promoted to reattach at its leading edge. The lift forces acting on the upstream and downstream cylinders showed the same frequency, while the phase lag between them varied with the distance.

This study intends to verify the validity of stochastic scour warning indices of a railway bridge pier which authors proposed. The scour experiment on a scaled bridge pier is conducted by step-by-step excavating ground around the pier. To identify the natural frequency of the specimen and calculate scour warning indices, microtremor is measured at each excavation step as well as impact hammer test measurement. This study also builds the Finite Element Model and conducts eigenvalue analyses for reproducing the experiment results and discussing the availability of scour depth estimation. The validity of the stochastic scour warning indices was verified as the stochastic scour warning indices clearly changed following the excavation progression.

In this study, we conducted on-site measurements of the live load response during train passage in a continuous steel-concrete composite twin box girder bridge. This revealed that the main girder began to tilt due to the static displacement during train passage. When we use the maximum displacement in checking the performance or soundness evaluation of the bridge, it follows that we should consider the measurement points taking into account of the displacement between the outer and inner web sides of the lower flange of a twin box girder bridge in order to select the right ones.

This study numerically investigates the effects of longitudinal distance between two stationary medium-sized trucks, laterally positioned in adjacent lanes, on their aerodynamic interaction under crosswind conditions through Large Eddy Simulation (LES). The focus is on the variations in aerodynamic force coefficients, pressure distribution, and flow field around the trucks. Aerodynamic forces coefficients such as side force and yawing moment of both upstream and downstream trucks varied significantly with their longitudinal distance, while the other coefficients were less affected. These variations were further discussed based on the flow characteristics and the interaction of vortices between trucks. These results provide insights into the aerodynamic stability of medium-sized trucks under crosswind conditions.

In recent years, studies to detect bridge damage from changes in vibration characteristics have been conducted. We studied estimation method of bridge natural frequency using stochastic subspace identification (SSI) with frequency bands separation method. However, the optimal values of some parameters have not been determined. And determining the parameter requires the judgement of engineer. In this study, a method of determining these parameters is examined, and we combine the results of this study and previous study to propose a calculation method of bridge natural frequency.

Japan and Taiwan, located in seismically active regions, face challenges from frequent earthquakes and aging infrastructure, requiring cost-effective and reliable structural health monitoring. This study introduces a new vibration-based approach using multi-accuracy sensors, integrating high- and low-precision sensors to balance cost and performance. Building on Optimal Sensor Placement (OSP) with cubic spline interpolation, we evaluate the feasibility of this mixed-sensor strategy through simulations and experiments. Dynamic response simulations under white noise excitation via the Newmark-β method, combined with Stochastic Subspace Identification (SSI), enable accurate modal parameter identification. Experimental results demonstrate this approach’s effectiveness, highlighting its potential as a scalable solution for structural health monitoring in earthquake-prone regions.

Early damage detection is crucial in infrastructure maintenance and management. However, maintaining a reliable power supply remains a key challenge in continuous structural monitoring. This study focuses on highway noise barriers, which can be damaged by corrosion, anchor bolt fatigue, and aging of embedded parts. Specifically, it examines the influence of changes in anchor bolt restraint force on the vibration characteristics and proposes power generation sensing using the piezoelectric effect. By analyzing the correlation between vibration modes and power generation energy, the findings demonstrate that power generation energy varies with the extent of damage. Furthermore, an analysis of uncertainty in the power generation response suggests its potential for effective damage detection.

One of the typical fatigue crack in welded girder of railway steel bridge is observed at the bottom of end stiffener. To repair the subsidence of bearing causing the stress concentration and the fatigue cracking at the bottom of end stiffener is burden on maintenance management. This study proposes the retrofit of end stiffener with the method with splice plate used bearing type bolt. This paper reports the results of static load test and cyclic load test conducted for evaluating the applicability of the proposed method.

Repair of the bottom flange in steel I-girders caused by corrosion is generally repaired by patch plates with high-strength bolt friction joints. However, the stress in the corroded flange in steel I-girders repaired by patch plates subjected to bending does not correspond with that calculated using the composite theory of cross-section of corroded steel I-girder and patch plates. Therefore, this study proposed a simple estimation method of the shared cross-sectional forces of steel I-girders repaired by patch plates using shear lag theory. The proposed equation can estimate the shared sectional forces with the same degree of accuracy as the results of FEM analysis.

In this study, the appearance rating method, which is now widely used to　diagnose the integrity of weathering steel bridges, was reorganized based on　photographs and the amount of corrosion in previous studies to clarify the　classification of each category. This clearly separated the categories that　should be repaired (Rating Number 1) from the others. In addition, it was　also possible to determine that the rusting changes over time would not　naturally shift to the rating number 1, although there is a possibility that the　rusting changes from rating number 5 to rating number 2 would shift　sequentially. This has enabled us to propose a more rational method for　soundness diagnosis during periodic inspections.

In this study, fatigue cracks at the flange ends of cross ribs in box girders were reproduced through fatigue tests, and the effectiveness of simple repair methods was confirmed. Additionally, the possibility of detecting fatigue cracks by measuring static strains without loading was verified. As a result, it was found that methods such as closing fatigue cracks with an automatic center punch, bolting the cracks, and the patch plate method could delay the initiation and propagation of fatigue cracks. Moreover, it was revealed that fatigue cracks at the flange ends of cross ribs could be detected by measuring static strains near the welds.

This study is focused on reaction forces at bridge bearings which may be relatively easy to access among other bridge members, and is aiming at estimating the damage state of a steel bridge and evaluating its structural integrity by measuring reaction forces at bridge bearings. In this paper, finite element analysis was performed on a 3D FE model of a steel I girder bridge. Results showed that when some main girders are corroded, reaction force at the support of the corroded girder decreased and reaction force at the support of sound girder next to the corroded girder increased, and that the horizontal reaction force caused by the deflection difference affects the vertical reaction force because the bridge is indeterminate structure.

In slip tests of thick plate joints, many experimental studies have reported that the slip capacity obtained from test results is often unstable. One of the causes of this instability is attributed to the warp distortion of splice plates that occur during the manufacturing process. Therefore, in this study, FEM analysis was conducted on frictional joints using inorganic zinc rich paint, parametrically varying the thickness of the splice plate and base plate, the warping pattern of the splice plate, and the number of bolt rows. The analysis revealed that it is necessary to consider the effect of warping for plate thicknesses of 60 mm or more, and stable slip capacity evaluation becomes possible with four or more rows of bolts.

This paper focuses on the mechanical slip behavior of box girder bolted connections consisting of slip-critical flange and web joints. Girder bolted connections resist the applied bending moment through the cooperation of flange and web resistances, which is called cooperative mechanisms. In the present study, FE analysis of steel box girder bolted connections was conducted to evaluate the slip strength considering the cooperative mechanism. As a result, it was confirmed that the box girder bolted connections had cooperative resistance mechanisms. In all cases, the overall slip strength was larger than 95% of the design overall slip resistance.

In this research, a method is developed to construct an FE model that reflects a slight decrease in plate thickness due to corrosion from point cloud data to evaluate the load capacity of an entire bridge including corroded members. As a case study, the cyclic test of an H-section beam corresponding to a brace member of a bridge is performed. Its FE model is based on a fiber model generated from the point cloud data, and the fiber elements in the corroded area, where local buckling is likely to dominate, are converted to a shell model. The MML model is applied as the constitutive equation of the steel to reproduce the complex behavior under the cyclic loading. Finally, it is confirmed that the FE analysis reproduces the loaddisplacement relationship and the deformed shape of the experiment.

Focusing on the girder end of a steel bridge, it tends to corrode easily due to the effects of moisture and dust. In the case of multiple plates are joined together under compressive stress, rivet head loss can cause plate separation. When this happens, out-of-plane deformation or buckling may occur, and affecting the load carrying capacity of the bearing members. In this study, 4 cases of loading experiments using removed riveted girder were conducted with different positions of missing rivets. It was found that stiffness decreased within a certain range of load in case of rivets at the lower ends of stiffener side and web side were removed simultaneously. However, all cases showed load carrying capacity almost equivalent to that of intact case.

Root-deck cracks have been observed from orthotropic steel deck (OSD) bridges under severe traffic conditions. These cracks are primarily caused by the stress concentration due to out-ofplane bending caused by heavy vehicle loads. The quantitative relationship among crack depth, load cycle, and fatigue life remains underexplored due to the difficulty in crack propagation measurement. Fatigue tests were conducted on specimens under varying load ranges to investigate the crack propagation behavior and clarify the fatigue strength of OSDs. Crack depths were estimated from the strain range reduction rate and the fatigue limit state was defined as the load cycle when the crack depth reached approximately 60% of the deck plate thickness. S-N curves were constructed based on effective notch stress.

This study conducted axial force fatigue tests on φ4 mm round bar specimens and plate bending fatigue tests on out of plane gusset welded joints t o clarify the effect of improving fatigue crack initiation life at the heat affected zone (HAZ) for fatigue crack intiation resistant steel. As a result, the effectiveness of fatigue strength improvement at the HAZ was clarified. The results of plate bending fatigue tests on out of plane gusset welded joints also showed that the fatigue initiation life improved an d the fatigue limit improved for fatigue crack initiation resistant steel compared with conventional steel.

In this study, static loading experiments were conducted to clarify the ultimate behavior of high-strength bolted joints subjected to shear and tension, with the flange plate thickness and angle of application as parameters. When the flange plate thickness of the joint is small, there is a range of angles where the fracture of the bolt progress from the shank to the thread portion. In contrast, this tendency was not observed when the flange plate thickness was greater, indicating that the thickness of the flange plate affects the location of bolt fracture. Additionally, a comparison between the design values and almost all of experimental values of maximum strength showed a difference of within 5%, indicating that the dsesign values are generally evaluated with high accuracy.

Laser ultrasonics, whereby an elastic wave of an ultrasonic frequency range is generated on the surface of a structural member using pulse laser irradiation, is applicable to noncontact and nondestructive testing. In this paper, the frequency is manipulated by switching the on/off status of the emission gate of a highrepetition-rate laser. The chirp signals are employed for gate control, thereby generating an ultrasonic wave in the range of tens to hundreds of kHz within the member. This technique is applied to measure residual thickness in metal plate members. The thickness can be estimated by detecting the cut-off frequencies of the non-zero order mode of a guided wave, especially zero-group velocity mode.

The authors have proposed a method for patch plate reinforcement using high-strength stud bolts that can be installed from one side. However, the effect of the stud arrangement on load transfer is not yet fully understood. This study investigates how different stud arrangements affect the mechanical behavior, including slip by using FEA. As a result, even when the number of bolts in the first row was small, the staggered arrangement effectively suppressed slippage at the edge of the patch plate. This confirms that the stud arrangement has a significant impact on the load transfer mechanism. However, its effect on the overall reinforcement of the patch plate was found to be minimal.

In this study, FEM was conducted to clarify the mechanical behavior and applicability of conventional design formulas for tensile type bolted joint using 1700MPa-class ultra-high-strength bolts. The 1700MPa-class bolts significantly improve the initial stiffness, the yield strength, the maximum strength and the deformation performance of tensile type joints compared to conventional high-strength bolts. Additionally, the conventional design formulas conservatively estimate the yield and maximum strength and bolt axial force of the joints using 1700MPa-class bolts.

The Specifications for Highway Bridges were revised in 2017 and stipulated for S14T, although the application is limited. The tightening force of S14T is higher than that of S10T, and there is concern about yield of the plates early. In addition, the contact pressure increases and the slip coefficient may decrease when the joint surface treatment is inorganic zinc. In this study, slip tests were conducted to deter-mine the effects of yield and contact pressure on the design slip coefficient of S14T high-strength bolt friction joint with inorganic zinc. It was concluded that the plate materials should be within the applicable of the Specifications for Highway Bridges, and that the design slip coefficient should be reduced to consider the effect of contact pressure when S14T is used with inorganic zinc.

The preventive maintenance method of cutting and treating the semi-circular at the vertical stiffeners in the orthotopic steel decks is often used. The authors conducted fatigue tests of the out-of-plane gusset welded-joint specimens by cutting and treating the semi-circular in the previous paper, however, it was not confirmed the effect of the semi-circular method due to the difference in boundary conditions with the actual orthotropic steel deck. Therefore, in this study, finite element analysis and fatigue tests using the box-type specimens were conducted to confirm the effectiveness of the semi-circular method. As a result, it was clarified that the fatigue strength is improved due to the reduction of bending moment at the weld toe by the semi-circular method.

The use of FEM is considered effective in complementing experimental results for high strength bolt tensile joints, and improving analysis accuracy is essential. In this study, we experimentally investigated the residual displacement and ultimate strength of high strength bolt subjected to repeated loads. We also examined a bolt model that can simulate experimental results. The results showed that significant residual displacement of the bolts occurs near the ultimate load. The analysis demonstrated that adjusting material properties improves the accuracy of reproducing both the ultimate load and residual displacement.

The number of bolts used in the connections of steel earth retaining beems (SERBs) used in excavation work is large because they are pressure-jointed with ordinary bolts. The number of bolts can be significantly reduced by changing to high-strength bolt tension joints. It is desirable to use high-strength bolt tension joints while utilizing the existing SERBs. In this study, cast-iron components were developed to be attached to the end plates and FEM analysis and structural experiments were conducted. As a result, it was confirmed that the stiffness and yield strength of the new joint structure with cast-iron components were equal to or greater than those of the conventional joint structure, and the time required to assemble the new structure was about 38% that of the conventional structure.

This study presents a method for evaluating the accuracy of axle weight estimation using Bridge Weigh-in Motion system. The study compares conventional methods, which assume white noise, with a proposed method that considers autocorrelation of dynamic component. The formulation reveal that the magnitude of the dynamic component does not affect the accuracy improvement by the proposed method. Analysis of measured data showed that the theoretical standard deviations of the estimating weight are consistently smaller with the proposed method, with a positive correlation between the standard deviation and absolute deviation, suggesting its potential for quantitative accuracy assessment even under complex vehicle traffic conditions.

This study experimentally investigated the effects of joint specifications and surface treatment methods of countersunk parts on the slip resistance of single-surface frictional joints using countersunk high-strength bolts with a head opening angle of 92◦. The results showed that the slip coefficient of countersunk bolts was higher than that of high-strength hexagonal bolts, and the slip coefficient remained unchanged even when rust-proof painting was applied to the countersunk parts. Additionally, it was found that using enlarged holes improved the slip coefficient by 3% to 7%. Furthermore, there was a tendency for the slip coefficient to decrease and its variation to increase when the slip-to-yield strength ratio was high.