Stress measurements of the newly built Koubo dam radial gates No.2 and No.3 were executed to obtain stress values in non-deteriorated condition for the future maintenance. While paying attention to the axial stress of arm near the trunnion pin, observed data were compared with FEM analysis results using the unified model that trunnion girder becomes a part of radial gate leaf. In addition, the reductive characteristics of load bearing ability in the future according to corrosion were examined analytically, and the necessity of thinking of trunnion girder as a part of radial gate leaves and consideration points in maintenance were investigated.

After the collapse of the I-35W highway bridge in 2007, the importance of redundancy of bridges has been recognized. Although the multi-girder bridges are generally classified as redundant structure, it is not trivial which member contributes the redundancy. As for composite girder bridges, decks and bracing systems have been found to be effective in distributing the load after the failure of the steel girder. For non-composite girder bridges, the contribution of decks is not clear since the composite action between decks and main girders has not been clarified. This study evaluates the contribution to the redundancy of cross beams and sway bracings through a series of nonlinear finite element analyses. As a result, cross beams and sway bracings are found to be alternate load paths.

In 1960s, bearing plate bearings had been developed as low friction and low height bearings for bridges. Among them, BP-A bearings were widely used in railway and highway bridges, but due to severe environmental conditions for a long period of time, they are deteriorated and sometimes causes serious problem of superstructures. In this study, horizontal and rotational cyclic loading tests of 40-years old BP-A bearings are conducted to evaluate the movement following performance. Especially because movement of the bearing plate is directly measured, the potential deterioration factors can be clarified.

The lean or slide of a substructure due to an earthquake or a flood, and the deterioration of a bearing support mortar make the support conditions of the line bearing inappropriate. Since this inappropriate support contidtions cause the stress of the girder end which isn’t considered in the design, the load carrying capacity of the girder end could be decreaced. In this study, the load carrying capacity and the bukling behavior under the inappropriate support conditions of the line bearing were evaluated by conducting the loading experiment with the full scale specimens of a ribet deck girder.

The inner surface of steel footing got corroded by the unexpected increase in the groundwater level. Its load capacity might be reduced due to the corrosion. FEM analysis was carried out the stiffened plate with a corroded inner surface, then the influence of the corrosion of the panel and the longitudinal stiffener on the ultimate strength was investigated. Especially, this analysis focused on a simple corrosion shape in order to obtain the lower limit of the reduction of ultimate strength. As a result, it was clarified that ultimate strength and deformation mode are different depending on the corrosion rate and shape.

Generally, the structural steel satisfies the material strength specified in the standards. However, there are variations in the strength and stress-strain relationship. The purpose of this paper is to clarify the influence of the stress-strain relationship of the material on the strength behavior of simply supported plate under in-plane bending and compression by numerical analysis. The numerical analysis used consideration of the following four kinds of changes of the stress-strain relationship; (a)material strength, (b)Young's modulus, (c)the gradient of strain hardening, (d)the difference of gradient between elastic and plastic areas. Finally, this paper proposed the ultimate strength evaluation method of the simply supported plate under in-plane bending and compression.

It is essential in the seismic design of concrete-filled tubular (CFT) structures to develop some analysis method that can be used to evaluate their superior post-peak energy dissipation capacity appropriately. Herein, a practical 3D segment model is proposed to reflect the complicated post-peak interface action between the locally buckled steel tube and the confined in-filled concrete. The segment model includes 18 parameters identified by an optimization technique, referring to the in-plane hysteretic behavior of the CFT members. The segment model analysis for the CFT structures dramatically reduces the long computation time required by the conventional FE analysis. A new direct seismic safety check method with the segment model is proposed.

Many countries around the world have plans to construct super long-span bridges including a new type of cable-supported bridge. Realization of long-span bridges requires development of new technologies to lead to reduction of the construction costs. For crossing wide straits, application of multi-span suspension bridges over 3 spans is one of economical solutions. However, structural behaviour of this type of bridge has not been fully clarified. In this paper, we focused on the ultimate strength of multi-span suspension bridges, and especially parametric analysis was carried out on the elasto-plastic behavior and load carrying capacity of the suspension bridge systems with different sag ratios and the number of spans.

This paper deals with a parametric study on safety of stay cables of cable-stayed bridges considering the factors affecting their ultimate and fatigue strengths. Currently, safety factor of 2.5 is used for the design of cable-stayed bridges in Japan but this safety factor has not been verified for various loading effects and unexpected damage conditions. The aim of the study is to clarify the safety and reliability of stay cables of cable-stayed bridges at various loading and structural conditions. For that, a finite element model of cable-stayed bridge is developed and static analysis is performed to explain how live load intensity, cable loss and corrosion affect the ultimate and fatigue demand to capacity ratios of stay cables. A probabilistic based reliability analysis is also performed to validate the deterministic finite element analysis results which indicates that the structural reliability solutions are rational and reasonable.

The application of spheroidal graphite cast iron to a bridge deck slab is explored. The deck slab is expected to have a good seismic resistance with little possibility of fatigue crack occurrence. Through a casting process, the spheroidal graphite cast iron deck slab was produced. Various material properties were tested and satisfactory results were obtained. The slab was then loaded statically. In order to ascertain the plastic deformation capacity, a large load of 941kN was applied to the deck slab. A static load-displacement curve of the deck slab was obtained. Furthermore, magnetic particle testing was carried out. There were no micro cracks. In addition, the results of the static load test were in good agreement with the results of the FEM analysis.

In this study, the deterioration prediction analysis is made by using the soundness evaluation value of each member in the inspection data that has been recorded in Ishikawa Prefecture. Because the inspection results contain inappropriate data for using in deterioration prediction, it is necessary to select data. A method is shown to identify the period in the deterioration progress and select the data to be used in the deterioration prediction by applying the piecewise linear regression. Many research and practical trials related to deterioration prediction by using the Markov deterioration hazard model are reported. Based on the current stored data, the deterioration prediction of Markov deterioration hazard model is compared with that of regression model.

In recent years, the problem of aging of infrastructure and countermeasures against lack of resources and technical shortage due to the declining birthrate and aging population are becoming a social issue. In maintaining and managing structures, it takes a great deal of labor and cost because there are huge numbers of stocks and high quality technicians are required to judge the deterioration factor at the time of inspection. This is a base study that aims to develop a system which mechanically judges the deterioration factor from photographs of deteriorated concrete structure with Deep learning which has produced many results in the field of image recognition and image authentication in recent years.

In order to manage the expressway assets, it is important to properly predict the scale of failures (lifting, peeling, crack, leakage, etc.) occurring in infrastructures in future. In this paper, the authors propose an initialization time model to predict the scale of failures. Specifically, the number of latent failure places where there are possibility of failure occurrence is followed to Poisson distribution. Furthermore, a time-dependent probability of a failure occurrence in latent failure places is expressed by using Weibull deterioration hazard model. In consequence, an initialization time model is formulated as a mixed probability model. Lastly, the authors discuss the usefulness of the model in this study through the empirical analysis of actual expressway assets.

Authors had already developed a calculated technique based on STRIP method to analyze additional slab, which is strengthened by two panels with free edges settled independently on upper surface of damaged slab. In this paper displacements and stresses neighboring joint between added panels and behaviors of opening at joint are rigorously calculated by means of previous technique respectively in case that additional slab is supported by rigid girder. Some numerical results of displacements and stresses considering effects by asphalt pavement in actual deck slab are compared near joint portion at additional slab under wheel loading. Also when working area of added panels is constructed partially, distributions of several stresses in the vertical direction near joint portion of additional slab are respectively discussed.

The evacuation simulation is carried on so as to grasp the evacuation behavior in storm surge flooding. In the result, the number of people who can complete to evacuate are increased by accelerating the starting time of evacuation. However, it is found that many people can be involved in the flooding despite the acceleration of the start of evacuation at a certain region. This is because that the time when the people pass a certain evacuation route is more or less same as the hitting time of flooding around the route. It is necessary to examine the evacuation behavior, such as the staying at a home, the start of evacuation, in reference to the numerical result which can expect the flooded area for any time and place since the evacuation behavior is different in a different region.

This paper presents a study on a high-performance seismic damper termed Buckling Restrained Rippled Plate (BRRP) damper. Focused in this paper is the establishment of the low-cycle fatigue performance of BRRPs as the ultimate limit state based on a series of experimental and numerical studies. In addition, the allowable fatigue damages of BRRPs that are so designed as to withstand three consecutive Level 2 earthquakes are introduced in order to verify the serviceability limit state.

This paper discusses the effects of local deformation, dent, and strain hardening properties on strain capacity in compression of a line pipe. Compression tests were conducted using dented pipes with an outside diameter of 400mm. A series of finite element analyses were conducted to investigate the compression behaviors. The compression capacity of a pipe was defined as the longitudinal critical remote strain whose strain distribution was free from the effects of a dent. Seismic integrity of the pipelines with a locally deformed pipe is discussed in accordance with the seismic design guideline issued by Japan Gas Association.

In this study, ductile fracture simulations from ductile crack initiation to rupture were performed on welded steel T-type joints. To this end, the three-stage two parameter ductile fracture model proposed in the past study was modified. Instead of the plastic displacement at element failure, a parameter was newly introduced to evaluate the ductile crack propagation of test specimens. As a result, the present analysis was able to accurately simulate the ductile crack initiation and propagation as well as the load-displacement relationship of the experimental result. It is concluded that the modified ductile fracture model can well predict the fracture behavior of welded steel T-type joints subjected to cyclic bending loading.

Three types of safety-check methods are presented for the seismic design of elevated girder bridges supported by hollow steel piers subjected to multi-directional seismic accelerations. The first method completely ignores the load redistribution among the component members in bridge piers. This concept is widely adopted in the conventional design practice. The second method only considers the load redistribution among the columns of the statically indeterminate bridge piers. The third method fully considers the load-redistribution among the piers in the statically indeterminate bridge systems. Based on numerical examples, the safety margins ensured by the respective safety-check method were discussed.

Cyclic loading experiments modeling steel piers filled with concrete were carried out to obtain basic data on the seismic performance. The steel-pier mechanical parameters, such as axial-force ratio and slenderness ratio, are assigned based on existing steel piers in Metropolitan expressway. The effect of axial-force ratio and slenderness parameters on the seismic performance are investigated through the experiments. The ultimate behavior of SM570 piers are almost identical with those of SM490 ones.

Many infrastructures in Japan were built during the period of high economic growth in the 1950s. Many corrosion damages have been confirmed at the corner, the base, and the top end of steel bridge piers. There have been few studies on seismic performance of steel bridge piers considered the effects of aging. Therefore, the seismic response analysis by dynamic analysis was carried out in order to clarify the seismic response behavior of the steel pier damaged by corrosion by numerical analysis.

Diagonal compression tests of masonry walls made of interlocking brocks with various shapes were conducted. I-shaped brocks with right angle, I-shaped brocks with obtuse angle, hourglass-shaped brocks with straight edge, and hourglass-shaped brocks with wavy edge were compared. It was found that the masonry walls made of hourglass-shaped brocks have larger strength and those made of I-shaped brocks have less. The finite element analysis was conducted to understand the mechanism. It was found that the walls with I-shaped brocks have less strength due to stress concentration at the interlocking part. It was also found that the walls with hourglass-shaped brocks have larger strength but larger displacement due to dislocation and rotation of brocks.

During the 2016 Kumamoto earthquake, a lot of structures including bridges suffered significant damages. This paper presents the damage analysis of Oginosaka horizontally curved bridge which suffered damages at the parapet of an abutment and residual bearing displacement, and also discusses fiber element analyses including deck-abutment pounding interaction to simulate the behavior of the bridge. The ground motions, including permanent displacements, simulated using the stiffness matrix method were applied to each column/abutment in the sumulation. Based on the analytical results, fiber element analysis with pounding could simulate the observed damages; damage of columns was minor while significant failure occured at a parapet wall and a restriction block on the abutment. Also, the residual bearing displacement in longitudinal direction occurred as a result of permanet displacement between two columns.

In this paper, a seismic retrofitting method using steel buckling restrained dampers to enhance the flexural and ductility capacities of existing RC bridge pier is proposed. Based on the cyclic loading test, the effects of the buckling restrained length and the ratio of flexural to shear capacities of the RC column on the horizontal load and displacement relation were investigated. A simple numerical method to evaluate the cyclic behavior of the RC column with the dampers is also presented. In an illustrative example, recovery time and seismic risk of a hypothetical bridge in the regions, where the effect of seismic shaking due to the anticipated Nankai trough would be intense, are estimated. The procedure for determing the number of dampers used in the as-built bridge is discussed.

When dampers are installed to a bridge, the damping force must be smaller than the resistance of the structure to be installed. However the resistance of the structure might be different between to the pushed force and to the pulled force, for example the abut with earth pressure, and the damping capacity must be chosen appropriate to the smaller resistance. Therefore, the asymmetric friction slip damper of which damping capacities are different between compression and tension was developed. In this study, the indispensable conditions of the asymmetric damper were clarified, and performance tests using actual dampers were carried out. As the results, seismic performance of the asymmetric damper can be estimated similar to the performance of the symmetric damper.

Laminated-rubber bearings and lead-rubber bearings have been commonly used for bridge bearings in Japan since the 1995 Kobe Earthquake. However, there have been some cases where laminated-rubber bearings were damaged during recent earthquakes. Therefore, there is a need for developing an alternative device for seismic isolation of bridges other than the rubber bearings. In some earthquake prone areas, such as the United States, spherical sliding bearings are applied for bridges as base-isolation. This paper presents a series of static cyclic loading tests of a bridge superstructure supported by four spherical sliding bearings as a seismic isolation system. The double spherical sliding bearing, having two facing concave plates and a slider, was used as the seismic isolation device. The theoretical mechanical behavior of spherical sliding bearings was verified by the experimental results.

Low frequency sound is supposed to be induced by the bridge vertical secondary mode vibration and has the maximum value - in the 10-20 Hz band - registered immediately after a large vehicle pass over the expansion joint. Considering the external force characteristics and in the bridge vibration properties, measures against the noise in the 10-20 Hz band were studied. The bridge and the countermeasures elements were modeled in 3D FEM and the vehicle dynamics effects were considered in the analysis. Based on those results, the main factors and the countermeasures effectiveness are discussed.

This paper investigates low frequency sound of a two-span continuous steel box girder bridge, three-span continuous steel plate girder bridge and three-span continuous prestressed concrete bridge. Those three bridges were selected as candidates to be constructed crossing a rural town since they satisfy conventional design criteria. In this study, velocity responses of bridges were estimated by a three-dimensional traffic-induced vibration analysis, and those velocity responses were used in sound propagation analysis by means of boundary element method (BEM), and the time-domain low frequency sound was examined by means of the inverse fast Fourier transformation (IFFT). Investigations demonstrated that the two-span continuous steel box girder bridge showed the lowest sound pressure level among three bridges.

Vibration monitoring has been established as one of the major structural health diagnosis method with emerged soft and hard based measurement technologies. The method would be effective for the management of infrastructures to recognize the level of structural deterioration by change of natural frequency. On the other hand, there still exist some problems for the environmental effects such as temperature and/or traffic excitation. The authors investigated the tendency of the change of the vibration characteristics, caused by temperature change or traffic excitation by the measurements of an existing bridge. In this paper, results of the series of the measurement for a three span continuous steel box girder bridge with various sensors and simulation results are discussed.

Bridge natural frequency is an important indicator of structural characteristics. Many studies have indicated ways to estimate bridge natural frequencies from vehicle passing. However, bridge natural frequency peaks are not easily observed because road roughness often influence the spectra. This paper proposes a new method to estimate bridge natural frequency from vehicle response. The method is based on the idea that the motion of tire includes two components; road roughness and bridge vibration. Subtraction of profile identified at the front tire from the one at the rear tire cancels road roughness and leaves only bridge vibration. Front and rear tire profiles are estimated from vehicle responses by Kalman Filter. Numerical simulation and field experiments show the bridge freuquency is extracted.

Recently, application of structural health monitoring to maintenance of infrastructures is extensively expected. In order to achieve practical utilization, however, both accumulation of data and evaluation method to derive information about structural condition from the measured data are highly required. The authors have been continuously conducting the measurement of long-term behavior and structural response for a taxiway-bridge in Narita international airport for almost 5years. Acceleration measurement and video systems have also been installed to monitor vibration property of the bridge. In this paper, long-term vibration characteristics and deformation against loading are investigated. Structural analysis is also introduced to evaluate mechanism and influence of various environmental factors on response of the structures.

Operational modal analysis that estimats the vibration characteristics using only dynamic response has been becoming mainstream. In the previous study the change of identification results depend on the configuration of calculation parameter was analyzed by using the analysis response of the microtremor simulation. Because the actual response was affected by the observed noise due to the external force to the excite state and the variation response. In this study, proper parameters are investigated by using the actual response, and the influence of calculation parameters by different excitation state and bridge type are considered.

After several decades of operation, belt conveyors in iron works suffer from severe corrosion on their support structures. While use of specific local vibration modes, Cross-Sectional vibration Mode (CSM), in the assessment through hammering tests with non-contact measurement had been shown effective, the hammering requires access to the support structure, which is practically difficult. In this paper, non-contact excitation of CSM using acoustic loading is investigated. Some modes, which are not CSM, are also excited. A method to distinguish CSM from other modes is proposed based on the cross sectional shape. After validation using FE models, CSM is successfully extracted in the acoustic excitation experiment, which indicates the capability of non-contact damage identification.

This paper introduces the details of a newly proposed “State Representation Methodology (SRM)” and its application to bridge condition assessment based on the bridge monitoring data. The SRM combined with the frequency slice wavelet transform (FSWT) which is a new time-frequency analysis tool was proposed for assessing a bridge condition based on the bridge monitoring data. This paper describes at first an overall description of SRM method via FSWT analysis. Then it will be demonstrated not only some new properties and advantages of FSWT analysis in contract to the traditional wavelet but also how accurate on feature extracting of SRM analysis for damage detection in a bridge system based on its monitoring data by using digital experiments.

It is important to evaluate the amount of salt on each member of bridge girders for effective maintenance. In this paper, the authors sought to propose a method for a long-term evaluation of the salt amounts by using a statistical method. Conducting the Monte Carlo simutaion based on probability distribution functions of meteorological data and airborne sea salt concentrations, the authors clarified that the salt amounts can be reproduced by the statistical method with consideration of correlations among random variables. Additionally, to describe wind direction using a probalitiy distribution function, a new method which decomposes wind speed and wind direction into two orthogonal components of wind speed was proposed. The effectiveness was shown using data from on-site observations.

In this paper, the wind flow mechanism of steel plate girder bridges is discussed based on computational fluid analysis. The analyis of steel plate girder bridges were carried out for the model which has four 3m height girders and its interval is 3m. As a result of analyis, the correspondance between experiment and analysis is confirmed, and it was observed that the distribution of drag coefficient is affected by the ratio of parapet and girder height, and it is found that the design method of lateral member is not necessarily safe side. The trial calculation of sway bracing based on the analysis were conducted. As a result of calculation the section of sway bracing needs to be changed from the one designed by the current design method.

In parallel circular cables arrangement, it is well known that wake-induced vibrations such as wake galloping (WG) and wake-induced flutter (WIF) are developed in downstream side cable by the action of the wake flow from upstream side cable. Due to strong exciting force of WG, the structural damping cannot completely suppress the vibrations, on the other hand, it is reported that the some surface configurations using helical wires can suppress the WG in the previous study. Besides, since the Karman vortex can be suppressed by the spiral protuberances on cable surface, the relationship between Karman vortex and wake-induced vibrations was investigated by using models with spiral protuberances. Furthermore, the vibration control of spiral protuberances was also investigated.

The purpose of this study is to estimate the stress introduced in steel plate with thickness-reduced section repaired by patch plates with high-strength bolts. First, to investigate the tendency of stress in thickness-reduced section, finite element analysis was carried out with several parameters of thickness and length of thickness-reduced section. Then, a simple equation of stress introduced in thickness-reduced section in steel plate repaired by patch plates with high-strength bolts was proposed. Additionally, the tensile tests of steel plate with thickness-reduced section repaired by patch plates with high-strength bolts were conducted to verify the availability of proposed equation.

In this research, to clarify the behavior of bearing with bearing plate used for 38 years, actual bridge measurements were carried out. As the results, it is clarified that the rotation and horizontal displacement of the bearings were not enough when live load acts. And although the horizontal displacements of the bearings by thermal deformation of the bridge were evaluated as good under global temperature variation, thermal stress acts on the bridge members by restraint of deformation by sliding friction of the bearing under daily temperature variation. Due to the sliding friction behavior of bearings, the thermal stress value is limited, therefore it is possible to evaluate axial force acting on bearing by actual bridge measurement.

A typical repair method for fatigue cracks in steel bridge members is the splice plate method. The crack tip is drilled out, and splice plates are added over the crack. For evaluating the remaining fatigue life of the repaired members, it is needed to know the stress of the drilled hole after adding splice plates. In this study, the effect of the splice plate’s geometric parameters on the stress reduction of a drilled hole was investigated by tensile tests and parametric FE analyses. As a result, a new method to estimate the stress of the drilled hole was proposed, considering stress carrying mechanism of the splice plate. This method could estimate the stress within 10% error.

Adding splice plates is a commonly used technique to repair fatigue cracks. The crack tip is drilled out before the splice plates are add. In some cases, however, a new fatigue crack initiates from the drilled hole. Because the drilled hole is entirely covered by the splice plates, it is impossible to measure its strain that can be used to assess the crack generation from the drilled hole. The purpose of this study is to propose a method to estimate the strain of the drilled hole by using a reference strain on the splice plate. By conducting parametric FE analyses and loading tests, the location for the reference strain which is strongly correlated with the strain in the drilled hole was proposed.

In this study, we discussed the fatige damage for an overhead transmission steel tower member during galloping. For this purpose, response charactristics of the tower were investigated based on a field observation. As a result, a standard deviation of member axial force due to galloping was three times more than that due to buffeting. In addition, the damage fatigue ratio for tower members was evaluated based on axial forces calculated using finite element analysis.

For repair of cross section loss due to corrosion, repair using high strength bolted steel repair plates is often performed. Two kinds of splice plate of friction type connection using high tensile bolt are connecting plate and cover plate. Such repair is carried out in order to recover the load bearing capacity. However, the mechanism of load transfer of base plate and cover plate is not obvious enough. Therefore, in this study finite-element analysis of repaired connection model using high strength bolted cover plate subjected to tensile load and compressive load was carried out in order to clarify this mechanism. As a result, relationship between sectional area ratio and load sharing ratio was clarified.

Tensile tests have been carried out in order to examine the slip coefficient of a high strength bolted connection of lap joint type with protective rust and identify factors affecting the slip coefficient. One of plates of the lap joint specimen is weathering steel with protective rust, another plate is new steel plate treated by blasting or with inorganic zinc-rich paint. In addition, tensile test have been also carried out on joint specimens suffered accelerating corrosion test in order to examine the change of slip resistance due to aging.

When high strength bolted frictional joints are used for repairing and reinforcing a steel bridge, the paint on the existing member is generally removed by using a disk grinder. Then, it is difficult to secure the required slip coefficient, because the frictional surface is finished smoothly. In this study, exposure tests, slip tests and observation of cross sections were carried out to investigate the performance of high strength bolted joints frictional in which the frictional surface rusted using the improved rust accelerator. As a result, the slip coefficient of the high strength bolted frictional joints which are rusted with the rust accelerator satisfied 0.40 and showed the possibility of the application of the rust accelerator to the civil engineering structures.

Epoxy resin is used for making the contact surface smooth when repairing or reinforcing steel bridge members by high strength bolted frictional joints. The load transferring mechanism of the joints where both high strength bolts and epoxy resin are utilized is unclear. Since the strength of cohesive failure of the inorganic zinc-rich paint is smaller than that of the joints of the adhesive, a reinforcing of inorganic zinc-rich paint is very effective measure by filling the air gap of inorganic zinc-rich paint. The tensile test for such joints has been conducted in order to investigate improving slip strength by using a primer and an adhesive, the timing of tightening and the bolt axial force.

A patch repair method using high-strength bolts needs the higher slip coefficients to transfer the stress from deteriorated steel members to patch plates. However, quality control of slip coefficients of contact surface on steel members is difficult on sites. In this study, the authors focus on the patch repair method using high-strength bolted connection with bolt holes filled up the epoxy resin. As the results of the tensile tests of patch repair connection, filled epoxy resin in bolt holes with the lower slip coefficient condition showed the bearing effect under the smaller loading. Besides, the bolted joint with bolt holes filled up the epoxy resin showed the higher slipping strength even in the low slip coefficient condition.

Deterioration of RC highway deck slabs due to repeated wheel running loads may be accelerated by superposing vibration load caused by bumps of expansion joints of bridges. This study was evaluated fatigue durability of wheel running fatigue test on running vibration load using RC slab specimens. The experiment were carried out fatigue experiment by a constant load. And conducted an experiment on running vibration loads with load amplitude of ± 20% and ± 30%. As result, the equivalent number of cycle of load applied load amplitude ± 20% and ± 30% of specimen is decreased 30% and 11% of the specimen with a constant load. Therefore fatigue life drastically decreases by running vibration. Based on the present test results, the S-N curves of RC slabs were proposed to evaluate the life estimation when vibration load is superposed.

The highway bridge decks which directly support heavy truck load have deteriorated caused by material factors, environment and wheel load etc. Recently damages of RC decks of steel bridges have been increased and some of decks have been replaced to precast PC decks. In this paper, deteriorated RC decks which were about 40years in service, have damages such as cracks and spalling of concrete, were conducted punching shear tests and wheel load running tests to verify load bearing capacity and fatigue durability. As the result, appropriate evaluation of RC decks can be achieved by not only visual inspection but also internal damage information was indicated.

Evaluation of the degree of deterioration by curvature had been investigated to make maintenance and management of the deck of road bridge. In the evaluation, the degree of deterioration was evaluated by Young's modulus aiming at the fact that the coefficients of the equation between Young's modulus and curvature can be represented by a simple curve. The results of the impact vibration test used as a simple test were evaluated by the curvature to check the soundness of the deck. It has become clear that the value of the Young's modulus is different from the obtained magnitude of the load is different It has been shown that rational optimization of the magnitude of the load is necessary.