In this study, the flood analysis is conducted to grasp the flood condition to evaluate the evacuation behavior under the flood caused by storm surge. In addition, the evacuation behavior under the flood condition is analyzed. As a consequence, it is found that the evacuation route and completion time depends on the existence or non-existence of flood. Under the flood condition, the jam-up is caused by many agents crowding the shelters since many roads and shelters are poorly functioning. Therefore, the residents should not grasp only the nearest shelter from domicile but also the shelter that is extremely has less possibility to be inundated with storm surge. In addition, it is necessary to evacuate even if the flood of storm surge is not recognized.
In this study, series solutions of anisotropic laminated plates using various thick plate theories based on displacement assumption are determined for accuracy verification of numerical method. By using this solutions, the accuracy of third-order shear deformation theory is clarified and selecting method of the displacement fields of third-order shear deformation theory is studied. In addition, a method for improving the accuracy of out-of-plane stresses of various thick plate theories based on displacement assumption is proposed.
Recently honeycomb panels are used in many fields such as architecture, aircraft structures and so on. FEM analysis is needed to investigate behavior of such complicated structures such as honeycomb panels, which can not be simplified as beam or plate. Since FEM analysis is influenced by meshing, boundary condition, element and so on, it is important to validate the accuracy by experiments. In this study we evaluate stiffness and local buckling behavior of honeycomb panels compared with grate panels by FEM and try to utilize their 3D printer models for experiments.
A stone arch bridge is one of the excellent heritages in the civil engineering. In order to maintain and to evaluate the seismic response of these bridges, this paper proposes a numerical analysis tool by using the finite element method as a discrete deformation analysis incorporated with the friction-contact analysis. We call this method “Discrete Finite Element Model” in this paper, and we implement this numerical analysis with commercial FE software “LS-DYNA”. The realistic FE meshes are generated, and material properties are acquired by material testing. Finally, efficiency and applicability of the 3-Dimensional FE model are demonstrated with numerical results for a static loading test and a dynamic response with one of the observed seismic waves at Kumamoto earthquake 2016.
Authors devised the new type of the connection which consists of high bond strength and high tensile strength filler only to overcome some faults of the loop connection in precast pre-stressed concrete slab. Prior to the assumed static or dynamic load test with full-sized model, the static load test with beam model including proposed connection has been conducted. And it is confirmed that polymer cement mortar and epoxy resin mortar are applicable to the test with full-sized model as a result. Authors also tried reproducing analysis with the nonlinear 3D FEM analysis program, “COM3D”, and confirmed that the fracture mode, initial stiffness, and failure load in the static load test can be reproduced with the FEM analysis.
Currently, aging bridges have become a social issues, there is an increasing demand for large-scale replacement. In the replacement RC deck of composite steel girder bridge, because there are a lot of problems, there is a need to propose a rational method that takes into account reduction of cost and shortening of the construction period. In this study, we focused on the replacement RC deck of the composite steel girder bridge. We conducted a framework analysis to examine amount of reinforcement of the main girder. As a result, it revealed that it is possible to effectively reduce the amount of reinforcement by removing the load distribution crossbeam partially.
Use of a recently developed lean duplex stainless steel JIS SUS821L1 contributes to reducing the life cycle cost of infrastructures due to its low material cost and relatively high corrosion resistance. This study aims to investigate initial imperfections and the ultimate strength of SUS821L1 welded stub-column with H-shaped sections experimentally. In order to supplement experimental data by numerical analysis including parametric studies, coupon test results and the measured residual stress data are compared to existing stress-strain model for stainless steels and predictive model for residual stresses, respectively. Based on experimental and numerical results, a formula predicting the ultimate strength of the column is proposed.
Stainless steels have advantage of high corrosion resistance and elongation compared with structural carbon mild steels. This paper presents the compressive strength behavior of stiffened plate which has a variety of stiffness ratio of longitudinal stiffeners and structural materials as well as plates slenderness based on numerical analysis. Firstly, combination of structural materials for the stiffeners and plate panels consists of the following four patterns ;(a) simple material, (b) material hybrid, (c) strength hybrid, (d) dual hybrid. At first, the strength behavior of these compressive stiffened plate models up to ultimate state is compared to that of stiffened plates with single material. Moreover, proposed is a strength evaluation method for the hybrid compressive stiffened plates with the stainless steels and carbon mild steels.
Stainless steels have higher corrosion resistance than carbon mild steels. Therefore, the stainless steel structures are expected to reduce their life cycle cost. In this study, the bending strength behavior of I-section beam made of stainless steels and carbon mild steels is clarified by numerical analysis. There are 31 patterns per one combination of I-section beam that change the material of the top and the bottom flange plates and the web plate. The pure bending strength behavior of these hybrid I-section beams is compared with I-section beam made of only carbon mild steel. In addition, this paper proposed the bending strength evaluation method of these hybrid I-section beam.
This paper presents a study on the ductility capacity of steel piled pipes repaired by steel patch plates, and also shows a study concerned with the maximum bending moment of repaired steel piled pipes. In this study, the cantilever FE model is used to study the ductility capacity of repaired steel piled pipes. This cantilever FE model is the partial model picked out a steel piled jetty. Based on pushover analyses of a number of cantilever FE models, an empirical formula on the ductility capacity of repaired steel piled pipes is proposed for the repair design of corroded steel pile.
A design method for achieving optimal viscous damper arrangement in multi-degree-of-freedom structure is presented in this paper. The optimal damper arrangement is realized by minimizing the object function which is the sum of the additional damper coefficients under constraints to be provided by allowable response displacement of each story. Giving the maximum response displacement of each story as the function of the additional viscous damper coefficients evaluated by use of the SRSS method enables to apply the nonlinear programming algorithm for solving the minimizing problem. The optimal damper arrangements for two sample structure models under the action of horizontal ground acceleration are implemented by the proposed design method and their reasonability is thoroughly discussed.
In this paper, the procedure for estimating the reliability of bridges and embankments subjected to ground motion and tsunami caused by the anticipated Nankai Trough earthquake is presented. Occurrence of a large earthquake along the Nankai Trough and the subsequent giant tsunami are predicted in Japan and it is expected that the damage and the economic loss caused by the event are more severe than those caused by the 2011 Great East Japan earthquake. In an illustrative example, reliabilities of bridges and embankments in Owase City, where the effects of both seismic shaking and the tsunami waves due to the anticipated Nankai Trough earthquake would be very intense, are compared to identify the structures with the lowest reliability and significant hazard.
The 2011 Great East Japan earthquake and 2016 Kumamoto earthquake triggered discussion about more practical concept for seismic design assuming very intense seismic action. One of such concepts is referred to as a redundancy. In this study, reliability-based seismic design methodology for bridge pile foundation is developed taking into consideration the difference of redundancy. Redundancy depends on the longitudinal or transverse number of pile foundation. In an illustrative example, partial factors to consider the difference of redundancy and to ensure the target seismic reliability for bridge under uncertainty are determined based on Monte Carlo simulation. Proposed partial factors can provide motivation to design the bridge with high redundancy.
There are enormous number of road attachment facilities on road network. It is important to prevent accidents due to collapse of those facilities. However, design method to prevent that accidents is not adopted in Japan. To establish the design method, evaluation method for time-variant risk for the collapse is essential. This paper proposes evaluation method for time-variant risk for the collapse of road attachment facilities, especially focusing on structural redundancy and deterioration. In addition, this paper verifies availability of the evaluation method through some trial of analysis and caluculation.
This paper deals with the elaborate modelling of stationary people in standing posture based on experimental and analytical results for the footbridge with the stationary people close to the center span. It is known that stationary human occupants act as dynamic mass-spring-damper systems and can change modal properties (frequency and damping) of civil engineering structures. However, there is a lack of information on the modal properties of footbridgs occupied by stationary people. Fundamental frequency obtained by a full scale measurement is compared with complex eigenvalue calculation using 2 degree of freedom ISO5982:1981 human model. Based on experimental and analytical results, it is revealed that all of the body weight does not act as TMD and that some of which act as an added mass to change the frequency of the footbridge with sand bags on the center span.
The rail corrugation on high rail often generates on ballast-less track, however its mechanism has been not known in detail yet. In this paper, first of all, we assumed that the track supporting stiffness under sleeper influenced the generation situation of high rail corrugation based on the results of the various field investigations. Then, we developed vehicle dynamic simulation models by means of multibody dynamics for verifying the influence of the track supporting stiffness. In addition, we simulated on-board measurement for verifying adequacy of analysis method. Finally, we examined influence of the track stiffness on the dynamic interaction between vehicle and track.
One of the mental and physical discomfort due to traffic vibrations generated by highway bridges is low-frequency sound. The maximum value of this low frequency sound in the 10 - 20 Hz band, is obtained immediately after a heavy vehicle passes in the vicinity of an expansion joint. The authors have analyzed the vibration measurement record of the vehicles and the bridges. It was then confirmed that the road roughness in the vicinity of the expansion joint causes the resonance of the vehicles and the bridge, and generates low-frequency sound in the 10 - 20 Hz band. Furthermore, a numerical analysis was carried out considering the road roughness in the vicinity of the expansion joints to determine the adverse factor on low-frequency sound.
In this research, we conduct the shaking table test by employing two types of steel pier models and investigate the amplitude dependency of dynamic properties of the models during free vibration behavior. We also confirm the elastic dynamic behavior of the pier models under an earthquake motion. Furthermore, we construct the analytical model including the amplitude dependency damping and make an attempt to reproduce the free and forced vibration behaviors of the pier model. As a result, the dynamic behavior of the model is successfully reproduced by employing the analytical model with nonlinear rotational spring at its pier base.
Deflection of a bridge is an important physical quantity, which is usually specified in bridge design. The deflection can also be utilized in the estimation of traffic load. However, the measurement of deflection is oftentimes not practical. Reference points for displacement sensor are usually not available. While deflection estimation by simple double-integration of acceleration measurement is considered to provide a simple and inexpensive deflection estimation, this approach suffers from integration errors when the integration duration is long. In this study, deflection estimation utilizing inclination is proposed. The vertical accelerations and inclinations converted from the longitudinal accelerations are fused through a Kalman filter to evaluate the bridge deflection. As opposed to acceleration-based deflection estimation in the past, the proposed method is in principle applicable to road bridges where multiple vehicles pass in series.
A three-dimensional visualization system was developed to investigate the dynamic state of structural components using portable sensors located at multiple points. The system utilizes wireless data transfer and real-time signal processing for on-site inspection. In this study, an angular velocity sensor and an accelerometer were mounted within each sensor box to enhance the accuracy of motion visualization. The performance of the system was checked using two mock-up reinforced concrete (RC) beams. In cyclic loading tests of the mock-up, we observed the natural vibration frequency and its mode shape with a hammer excitation. Disturbance of the initial motion may potentially be used to indicate crack initiation. Furthermore, it was shown that deviations in the mode shape allowed evaluation of the damage state.
At steel girder edges, remarkably reduced thickness, which is caused by steel corrosion due to water leakage from the expansion joint, is observed and leads to the reduction in the load-bearing capacity. However, in order to grasp the thickness reduction amount, the important challenge in many cases is to remove the rust. Additionally, it is also an obstacle for the health evaluation. For this reason, to understand vibration characteristics in the case where the lower end thickness of the web panel has been reduced, this study investigates soundness evaluation method based on the MAC by concentrating on web vibrations, local measurements, and numerical analysis.
This study is aimed at constructing the traffic volume estimation models. To construct the prediction model, the bridge acceleration data and traffic volume of target bridge were acquired. The multiple regression analysis was adapted as the method of constructing the prediction models. Measures related to dynamic response waveform were used as the features of this study and to be considered for explanation variables. By a procedure based on the correlation analysis, the suitable variables were determined and the estimation models for ten-minute total traffic volume and the truck traffic volume were constructed. From those results, the constructed estimation model showed good agreement with the traffic volume data.
Kouzono Overbridge, Kiyamagawa Bridge and Furyo Overpass No.1, which are located near the epicenter of the 2016 Kumamoto earthquakes, were damaged due to the strong motions. In order to analyze the damage mechanism, it is very important to evaluate the strong seismic motion at the bridge sites of interest with high accuracy. First of all, aftershock observations were carried out at the bridge sites of interest in this study. Next, the empirical site effects were evaluated based on the records. Finally, seismic waveforms at the bridge sites of interest during the 2016 foreshock and the 2016 main shock were estimated based on the site effects. The estimated seismic waveforms will be useful for a rational safety assessment of an expressway bridge.
Okirihata Bridge, Kuwaduru Bridge, Oginosaka Bridge, Tawarayama Bridge, Aso-Choyo Bridge, Minami-Aso Bridge and Aso Bridge, which are located near the epicenter of the 2016 Kumamoto Earthquake were damaged due to the strong motion. In order to analyze the damage mechanism, it is very important to evaluate the strong motion at the bridge sites of interest with high accuracy. In this study, aftershock observations were conducted at the bridge sites of interest in order to evaluate the empirical site effects. Seismic waveforms at the bridge sites of interest during the 2016 main shock were then estimated based on the site effects and the characterized source model. The estimated ground motions will be useful in the detailed study of the damage mechanism.
At Kumamoto earthquake on April 16, 2016, at 1:25 AM, the jumping behavior of the unanchored wooden structure named Chozu-sha was reported. To explain it in view of dynamics of discontinuous systems, the Chozu-sha is modeled by two-story rigid rectangular block, and its equations of motion are derived. Employing a corresponding recorded accelerogram, its jumping motion is computed. Comparison of the jumping distance computed with that reported yields that the proposed procedure may explain a major mechanism of the jumping of the Chozu-sha. Its essence is that the jumping distance is elongated if the horizontal acceleration which is larger than the rocking commencement acceleration but is smaller than the maximum acceleration lasts longer.
The effects of the anchorage length of the post-anchored SD490 bars into the existing footing and the spacing of those bars for the longitudinal reinforcement in RC jacketing on the anchorage capacity were studied and details of the post-anchored SD490 bars were verified. Furthermore, a pier wall model retrofitted by the RC jacketing was designed with the verified details for the post-anchored SD490 bar, and a cyclic loading test was conducted for the retrofitted pier wall model. Test results show that the post-anchored SD490 bars performed well and the increase of the flexural strength coincide with the expected target.
In the current JSCE seismic design code for steel and composite structures, the safety of structures is verified by checking the condition that the response strains calculated by geometrically and materially nonlinear dynamic analysis are within the ultimate strains specified by the pushover analysis for respective structural segments. Herein, the validity of the strain ckeck method is discussed from two view points, The first point is whether or not the strain check method includes the overall stability check of structures. The second is whether or not the the ultimate strains determined by the pushover analysis is accurate enough.
In this study, the use of buckling-restrained braces (BRBs) as energy dissipation dampers is attempted for seismic performance improving of steel rigid-frame piers. The effectiveness of BRBs which connected the steel rigid-frame piers through a bracket to protect the structures against strong three times earthquakes is examined by Hybrid test. Compared with the seismic response of the original structure without BRBs, satisfactory seismic response is seen in the strengthened models, which clarifies the effectiveness of the proposed BRBs seismic control design, and it can serve as an efficient solution for effective reinforcement of existing steel rigid-frame piers.
As one of a seismic reinforcement device, Shear Panel Dampers (SPDs) made of steel are used as a seismic damper. Since the aluminum alloy is a lightweight and material superiority against steel, there is worth considering as one of the seismic damper. In this paper, performance tests and analysis of Aluminum Shear Panel Dampers are studied. An aluminum deck of square-hollow sections made of aluminum alloy (A6061S-T6) were used for test specimens. In the tests, monotonic and cyclic loading was applied. As a test result, brittle failure has occurred in shear deformation in less than 6.5%, the Cumulative Inelastic Deformation (CID) was less than 24%. By numerical analysis, it was possible to substantially simulate the test results.
This paper investigates the consequences of so called fling-step characteristics of near-field ground motions, which is originated by the permanent ground deformations due to a fault, on the damage of bridge caused by the 2016 Kumamoto earthquake (MJMA7.3). To simulate ground motions including permanent displacements, the stiffness matrix method is used and the fibre element method is adopted to compute the 3D nonlinear responses of a bridge. It is found from the study that recorded ground motions and the bridge damages can be finely simulated.
After 2011 East Japan earthquake disaster, many researches have been conducted to reveil tsunami-induced forces on bridges, however, most of them account for bridges without skew. Skewed bridges suffer not only transverse tsunami-induced force but also longitudinal force. This paper discusses difference between the tsunami-induced force for bridges with and without skew. The hydraulic experiments and 3D numerical analyses were conducted. The results showed that the maximum transverse forces are almost the same for bridge models with and without skew.
When tsunami damaged the coastal structures of Kuki fishing port, the 1/4 wave length, 1/4 wave period and wave height was 30m, 2sec and 7m, respectively. Besides, based on the video analysis, it is noted that bore wave occurred near Hironai Bridge. Both of its horizontal acting force and vertical acting force were more than twice of the girder resistance force of Hironai Bridge, which coincided with the damage situation.
Recently, on the surface of bridge base-isolated rubber bearings, quite a few cracks due to ozone deterioration are reported. In order to use bridge rubber bearings for a long term, the repair of the ozone cracks is indispensable. In this study, we performed the repair by using coating materials in ozone cracks of the bridge rubber bearings, and carried out a series of experiments to evaluate the repair performance of coating materials. Furthermore, we carried out ozone degradation accelerated exposure experiments to evaluate the ozone deterioration characteristics of the synthetic rubber materials which were superior in ozone resistant.
Bidirectional shaking table test of concrete bridge pier with friction pendulum isolation system (FPIS) is conducted in this study. It is confirmed that proposed bridge pier has oscillation frequency decreasing with sliding displacement, and the restoring force has an upper bound so that the force transmitted to the bridge pier and foundation is very limited. Effect of the curvature radius of FPIS, arrangement of bridge piers, and seismic intensity of transvers ground motion on the dynamic behavior of the bridge is investigated experimentally. Optimal variable surface of FPIS and arrangement of bridge piers to maximize the seismic performance is examined. Numerical simulation method for the proposed bridge pier with FPIS subjected to the bidirectional ground motions is also discussed herein.
Rupture of isolators should be prevented in view of post-earthquake repair time and cost. In this study, effects of strength ratio variation between isolators and reinforced concrete columns due to deterioration of isolators on the seismic failure modes of isolated bridges were investigated considering uncertainties in the material and mechanical properties of isolated bridges. As a result, it was shown that it is important to set the strength at hardening initiation of the isolator to be larger than the ultimate strength of the column in the seismic design to maintain seismic safety of bridges with deteriorated isolators. It was also indicated that rupture strain of isolators is a major uncertainty in evaluating the ultimate failure modes of bridges with deteriorated isolators.
This paper investigates the physical mechanism of corner-cut on aerodynamic stability in a rectangular bluff body by using Large Eddy Simulations. In corner-cut case, the flow attaches at 1st and 2nd leading edges and high frequency components of velocity fluctuation are more active at the trailing edge area, therefore they enhance or stimulate the reattachment tendency of shear flow on side surface and keep the Karman vortex form further from the rear side of the bluff body. As a result, the size of wake structures is much smaller, the recirculation length is longer, therefore, the value of drag coefficient and Strouhal number changes significantly.
This paper presents the results from a state space stochastic system identification to extract flutter derivatives (FDs) under different turbulent flows. The aim of the study is to clarify the effects of oncoming turbulence on the self-excited force of a suspended long span bridge deck by using a section model. In the study reported herein, the more challenging is the application of a system identification method to identify FDs from gust responses for the section model. The gust response is obtained by an experimental wind tunnel test and simulation for a trussed deck section. The output only time domain analysis stochastic system identification is proposed to extract simultaneously all FDs from two degrees of freedom system. The results are also compared with those fromsmooth flow and free decay response.
Since the aerodynamic stability is one of the most important issues to realize the long-span bridges, various studies were carried out and the latest findings were applied to the construction of the Honshu-Shikoku Bridges. However, the all countermeasure for aerodynamic stability may not be necessary at the maintenance stage. Therefore, it was required to confirm the aerodynamic stability of maintenance stage. In order to consider three dimensional effects, 3D flutter analysis which was developed for the Akashi-Kaikyo Bridge was carried out using the aerodynamic forces measured by the 2D wind tunnel test. As a result of this study, it was found that the aerodynamic stability is kept at maintenance work.
One of the reasons of corrosion of bridges is airborne sea salt. The purpose of this study is to reduce the amount of sea salt adhesion by applying aerodynamic countermeasures such as noise barriers, horizontal plates and vertical plates to change the flow pattern around a bridge. The study bridge is composed of 8 I-shaped steel girders, which is the most typical shape in urban expres sways in Japan. The steady flow of wind around the bridge was analyzed by computational fluid dynamics (CFD) while changing the combination of additional devices. The results showed that simple additional devices can reduce the amount of airborne sea salt adhesion.
Weathering steel bridges have been constructed in the region where little salt is found. But these days, some of these bridges are much corroded. To estimate the condition of bridge site in detail, our group started exposure testing using weathering steel ball. The advantage of using steel ball is, because of this shape, the condition of bridge sites can be estimated in all direction.
The deterioration of a bridge is promoted by water on the surface. On the other hand, some water drops due to condensation are expected to run down bridge surfaces and then wash off salt on the surfaces. Therefore, it is important to estimate the salt amounts on bridge surfaces considering the washing-out effect of condensation drops to achieve effective maintenance. The authors sought to estimate the amounts of water formed on steel bridge girders on the basis of the 1-D heat conduction equation, and investigate the conditions for a water drop to run down a surface and the amount of salt removed by a drop. The salt amounts calculated on surfaces were decreased with the washing-out of condensation drops.
Surface preparation is very important in re-painting of steel structures so as to extend the effective term of corrosion prevention. Though grinding or blasting have been widely used to remove rust and old coating film on steel surface, both these methods have some difficulties in completion of rust-removal and cause some problems such as dust scattering, noise, etc. This paper presents the laser cleaning method which instantaneously sublimes/evaporates the rust on the surface of steel structure. It is concluded from the experimental results that laser cleaning can remove not only rust but also salt on the steel surface . The basic data is provided for further dissemination of laser cleaning.
Recently, for the repair of corroded or fatigue damaged steel members, bonding patch plate have been proposed and applied. One of the concerns of this method is prevention of debonding of patch plate, because the shear and peel stresses in adhsive layer concentrate at the end of patch plate. In this study, the equation for calculation of stresses in adhesive in single lap joint under tensil or bending condtion. Furthermore, the tensile test and bending test of single lap joint were carried out to evaluate the debonding condition with applying the adhesive stresses. As a result, it was shown that the energy release rate and principal stress calculated by the adhesive stresses are able to evaluate the debonding of patch plate under tensile load or bending.
While the use of plate bonding method to repair or strengthen steel structures started to be accepted, the influence of temperature state of steel members on the reinforcing effect of plate bonding method and endurance of bonding are concerned. In this research, steel and CFRP plates are bonded on to the lower surface of bottom flange in main girder and onto the lower surface of orthotropic steel deck plate in service, and strains on the patch plates during the adhesive curing and applying the traffic loading were measured. As a result, it was found that the adhesive layer were completely cured under the service. Furthermore, it could be observed that the strain transfer ratio in the case of bonded patch plates on the bottom flange was constant through the season, while the strain transfer ratio in the case of bonded patch plates on the deck plate was depended on the season.
When functions of bearings in steel I-girder bridges are lost due to generation of rust and so on, it is known that fatigue damage is prone to occur there. Some methods for improving fatigue durability of this part have been proposed and actually applied, but the most suitable countermeasure and the specific structural detail are not clarified yet. This study aims at improving fatigue durability of the bearing in existing steel bridges by relatively easy repair methods which are adding a vertical stiffener, finishing the weld toe and deepening weld penetration of the welds between sole plates and lower flanges. Effects of above-mentioned methods have been examined through stress measurement tests, fatigue tests and FE-analyses on model specimens.
In the welded joint, a tensile residual stress introduced by the weldeing is reduced when the crack initiates and propagates. Therefore, if the residual stress near the weld joint can be measured, it will be the fatigue crack detection method. Recently, residual stress in steel members is able to be measured by X-ray diffraction method on site. Therefore, in this research, a residual stress measurement using X-ray diffraction method is proposed for the detection technique of fatigue crack. To confirm the proposed methods, specimens of out-of-plane gusset joint and the specimen of joining between orthtorpic steel deck and U-shaped rib were tested under cyclic loading with measureing the residual stress. In the results of fatigue tests, the chaninging of the residual stress near the weld joint by the initiation and propagation of fatigue crack was observed by the proposed technique in all cases.
Many fatigue cracks were found at the connections between girder-floor beam and girder-way in a simple supported composite girder bridge. The fatigue cracks occur in 40 years. Thus this fact implies that the fatigue cracks may occurred due to poor connection details. Therefore, fatigue retrofitting is planned for the bridge. This study is aiming to clarify the effects of retrofitting on stress reduction by FEA with sub-modeling technique of the bridge and its retrofitting. FEA results showed that retrofitting by splicing with weld bead removal can reduce local stress under 10% of original, and that retrofitting for the top of web-gap plates and vertical stiffeners could reduce local stress to 60-70 % of original.
The axle-box acceleration (ABA) is regularly measured by the track inspection car in major Japanese railway operators. We developed a new technique for managing rail corrugation by making use of the ABA measured by the track inspection car. Concretely, we analyzed the relation between the ABA data and the rail surface roughness data measured on the ground. Furthermore, we examined the influence of the measurement axle in the bogie and the train running speed of the ABA on the detection accuracy of the rail corrugation by using the ABA. As a result, we have confirmed that the rail corrugation can be managed efficiently by using the ABA measured by the leading axle of the bogie in case where the track inspection car runs with a usual speed.
Cyclic load by train causes subsidence of railway level in tunnels, which is due to ground deformation under roadbed concrete. In this study, to develop a method for quantitative evaluation of train running stability on the slab track, a method to survey roadbed concrete by vibrating with small-sized vibration exciter was proposed. Vibration characteristic of roadbed concrete with accelerometers fixed around the vibration location was also evaluated. Then the correlation with progress of track disorder considered to be correlated with the soundness of roadbed concrete and the vibrational energy provided in vibration tests was verified, and a method for evaluation with the correlation was proposed.
In strain measurements for bridge maintenance, determining the position of the travelling vehicles is important because the strain response significantly vary depending on the position of the travelling vehicles. However, the conventional methods were not able to determine the position in a road width direction of the travelling vehicles accurately. This paper proposes the method to determine the position in a road width of that using image processing technique. In order to verify the proposed method, field measurements in a bridge in service were performed. Based on the experimental results, the proposal method was able to achieve accurately vehicle travelling position with practical processing speed.