This research is focused on the damage estimation of the underground reinforced concrete structure placed on the fault line in case of the fault rapture. 3D FE analyses, of which taken both soil and reinforced concrete non-linear behaviors into consideration were applied to clarify the relations between the fault rapture and the fracture mode of the structure. Different fracture modes of the structure, in terms of the direction and the dislocation of the fault rapture, were observed in the results. In addition, two limit fault dislocations focused on the structural performance, one is the member failure limit and another is the structure destruction limit, were proposed.
Recently, the polarization resistance method is highly noticed as a non-destructive test method to evaluate the corrosion rate of rebar in concrete structures. The corrosion rate can be estimated from the apparent polarization resistance and the polarized area. The polarized area is often evaluated by numerical methods such as boundary element method. The material heterogeneity such as rebar corrosion or altered concrete is one of the most important affectors on the current propagation in a reinforce concrete. However, it is not well evaluated by boundary element method. Thus, in this study, finite element method is employed to evaluate the current propagation. In the results, the properties of current propagation are strongly affected by the material heterogeneity.
Adhesive resin is the important material to bond the strengthening material with concrete substrate and transfers the force between two materials. Adhesive layer plays a major role for debonding strength. This study attempts to find a way to enhance debonding strength through investigating the influence of adhesive layer property, such as thickness and inclusion of FRP sheet on the bond behavior between UFC and ordinary concrete (for concrete cohesion failure), and the bond between steel and steel (for adhesive layer failure) under direct shear test by using nonlinear finite element analysis. The results indicate that adhesive thickness strongly affect the debonding strength. However, FRP sheet inserted to adhesive layer shows small effect on the debonding strength.
Although hot dip galvanizing is a method of giving long-term corrosion protection to steel structures, steel materials may suffer cracks and/or distortion during hot dip galvanizing due to abrupt changes in temperature. As measures against cracks, beam-to-column welded connection with non-scallop methods having draining holes may be applied. However, there are some cases that cracks occurred in spite of taking such measures. Therefore, in this study, we carry out immersion tests into molten zinc using specimens which changed the diameter and the position of draining holes for the partial model that assumed beam-to-column welded connection. Furthermore, the measures that can reduce possibility of cracks are examined by using the three-dimensional thermal conductivity and elastic- plasticity thermal stress analysis.
Recently, some PRC girder bridges of Shinkansen were found to have unexpected large amplitude vibration. The girders' natural frequency estimated by the impact test was 13 % larger than the excitation frequency caused by Shinkansen passing. Thus, the mechanism cannot be simply explained as resonance in the linear system. We conducted vibration measurement and found the natural frequency becomes lower as amplitude becomes larger. By conducting FE analysis considering the effect of the amplitude-dependent nonlinearity of stiffness and Shinkansen's vehicles weight, natural frequency is found to decrease and get close to the excitation frequency and instantaneous resonance during Shinkansen passing can occur. We also analyzed the long-term trend of structural characteristics by using the vibration data continuously measured for several years. Then, we found the natural frequency varies clearly depending on the temperature.
Cable-stayed bridges are generally designed with sufficient redundancy which provides the capacity to maintain stability under effect of one cable loss. In such event, factor for impact force of 2.0 is specified by Post-Tensioning Institute's recommendations. This study aims to evaluate the factor provided by the PTI and confirm the structural response of a cable-stayed bridge model encounter sudden cable rupture. An experimental program was performed to simulate the cable rupture event, with specimen being chosen strictly based on the rule of similarity. The obtained strain - time wave forms were used to calculate important parameter such as impact force factor, rupture time, strain velocity, and vibration frequency. The dynamic response analysis method using the strain wave form from the experimental program was suggested and showed its advantage over the static analysis recommended by PTI.
Since the accident of the I-35W Mississippi river bridge in 2007, a lot of research on the redundancy based on numerical analysis has been conducted. Although there is a lot of research related to truss bridges and girder bridges, there is few research about Langer bridge. Since Langer bridges are regarded as statically indeterminate structure in the design process, we can expect that Langer bridges are more redundant than statically determinate structures such as truss bridges. However there is no research on quantitative evaluation of the redundancy of Langer bridges so far. In this paper, influence of modeling of panel points and slab on evaluation of the redundancy of steel Langer bridges is investigated through a series of nonlinear finite element analyses.
A tangential plasticity model has been adopted to more accurate predictions of cyclic loading behavior of a thin wall bridge pier under the bidirectional lateral non-proportional loadings. According to comparing a numerical simulation result with an experimental result and that from the conventional plasticity, high applicability of the tangential plasticity model has been confirmed. Moreover, numerical analyses by the tangential plasticity model and the conventional one have been conducted to investigate the differences of the responses under other seven bidirectional cyclic loadings, the results indicate the importance of considering the tangential plasticity effect in order to achieve more accurate and reliable predictions under operational loading conditions.
Gusset plates of a joint in a steel truss bridge are the key parts of the structure system, because they are connecting several main truss members. However, the detailed failure mode of gusset plates subjected to compression has not been well examined yet. Therefore, this paper discusses the failure mechanism of the gusset plates of a joint subjected to compressive force through the diagonal member. The failure mode is examined by both numerical and experimental method. And It is clearly shown that the failure mode demonstrated by these two methods are quite consistent with each other. Then, a strength equation for the gusset plates subjected to compression is finally created on the basis of the failure mode.
In this paper, the ultimate strength of aluminum alloy girders in bending is investigated. First an equation to estimate the ultimate strength of girders in bending is formulated. Next the elastic-plastic large deflection analysis with FEM provides a formula to estimate the ultimate strength in the lateral direction of a flange. Finally FEM analyses are carried out to confirm the validity of the equation established for the ultimate strength of girders in bending.
For a PC connected girder bridge, a new connection system that pretensioned girders were connected via precast cross beam supported on bearings (SCBR Method) was proposed. As for the proposed structure, construction cost was reduced in comparison with conventional structures, and maintenance became also easy. In this study, to apply this connection method to pretensioned hollow girders and pretensioned T-shaped girders, loading tests on the connection parts using full-size test specimens were carried. As a result, sufficient distributions of cracks and enough ultimate strength was confirmed. In addition, Non-linear FEM analysis in comparison with the experiment was carried out to establish a performance evaluation method of the proposed structure using the analysis.
Structural Optimization, Reliability and Expert System
Ensuring the connection of the road network is an urgent needs in Japan where are a lot of disaster such as an earthquake or the guerrilla rainstorm. In addition, nowadays the effectively and deliberate road improvement plan is needed because of the financial difficulties. For this reason, it is necessary to evaluate comprehensively the improvement of the consolidated reliability of the road network and the cost for the infrastructure improvement. This study reduced the calculating cost of exact consolidated reliability by using the topology transformation. Also, this study proposes a prioritization method in the maintenance planning with evaluating the consolidated reliability and travel time and repair costs comprehensively.
It is most important to propose the evaluation technique of the unpleasantness which a human body receives due to bridge vibration. In this study, the experiment to measure physiological information was performed in order to propose evaluation technique of serviceability of pedestrian bridges. In the experiment, the vibration of both pedestrian bridges and pedestrians were measured simultaneously, and the relation of both vibration characteristic and the biological pulse wave have been investigated. As the result, it is found that the Lyapunov exponent of biological pulse wave could be used as an index for evaluating the unpleasant bridge vibration which pedestrians feel.
The objective of this paper is to establish the method to explain technology for creating the reliability between people and engineer. Therefore, the view with which the risk communication model about formation of the risk perception in social psychology or reliance and the idea about new engineering accounting were united was established. The homepage about the maintenance management of the road structure in Fukushima Prefecture was made into the example, the issues on technical explanation were summarized, the contents were corrected using the method, and the effect was investigated. It is found that a new technical explanation method is useful because intelligibility increased from correction before and by having used the method.
In this investigation, the data and current maintenance status of existing bridges in Vietnam, as well as the bridge properties and deterioration characteristics were confirmed, based on the data obtained through the business of the Ministry of Foreign Affairs in 2013. In addition, through the analysis of 40 bridges in Vietnam using Bridge Management System (I-BIMS), the result showed that despite several confirmation results of issues on BMS application, it was confirmed that it was possible to apply the Japanese BMS to Vietnam.
In this paper consist of three parts; 1) An identification methods based upon actual inspection data in order to carry out strategic maintenance for bridge and tunnel structures in cold region. The resistance of deteriorating bridge and tunnel structures is non-stationary stochastic processes, and reliability problems of such structures are essentially different of time-independent reliability problems. 2) Log-normal distribution shows excellent fit with various data on the durations of disabilities, irrespective of their severity. Persisting long tails suggest the fractal nature of disability distributions. Finally, numerical examples are worked out to demonstrate the usefulness of this estimation method for Bridge Management System and Tunnel Management System. And long tails of the duration distributions for the bridge and tunnel lining are analyzed.
In this study, a model was proposed in order to estimate initial stresses such as a stress at the erection of a PC bridge. A simplified analytical model was applied and the modelling was confirmed by investigation of stiffness of the lattice members. Although the model was simple and of practical use, analysis of a PC box girder bridge gave results of the initial stresses with standard accuracy. Also the applicability and problems when using the proposed model in design were shown.
The acceleration sensor may play an important role in health monitoring of civil engineering structure, because it is easy to install and a low purchase price. As the acceleration under live load at low frequency is small, it is important to know not only sensor self-noise but also the required signal-to-noise (S/N) ratio. In the present study, field measurement were first performed in order to compare the acceleration response between 9 different accelerometers under live load. The negative effects of sensor self-noise were then evaluated by the results of double-integration process. Finally, using a shaking table whose frequency and amplitude could be varied parametrically, S/N ratio required to accurately measure the response at low frequency range was estimated.
One of the essential challenges facing the research and development on structural health monitoring system for civil infrastructures has proven to be time synchronization among the huge number of sensors required. As a conventional technique for synchronizing the time among multiple sensors, GPS signals are available; however, these signals are not available in many places and below ground. To resolve this problem, autonomous sensing technology was established to ensure highly accurate time information using chip scale atomic clock (CSAC). In this study, fundamental research of the autonomous sensing technology using CSAC is introduced and performance evaluation test for the developed prototype sensing module is also presented.
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. A full scale measurement is carried out to investigate the influence of stationary people on a existing footbridge with center span length of 12m. Complex eigenvalue calculation is also conducted using 2 degree of freedom ISO5982:1981 human model for 9 bridge models with fundamental frequency of 1.0Hz-9.0Hz in addition to above-mentioned existing footbridge. Based on experimental and analytical results, it is revealed that the structural damping of the footbridge increases according to the increase of number of stationary people on the center span of the bridge due to the dynamic interaction.
VRA (Vehicle Response Analysis) method has been proposed as a method of bridge screening. SSMA (Spatial Singular Mode Angle) is one of the proposed indices of VRA and indicates bridge mode shapes, which can be estimated by using only vehicle vibrations. SSMA rarely shows the correct bridge mode shape, but it has the high sensitivity to bridge damage. However, the previous studies have carried out only simple numerical simulations based on FEM. In this study, numerical approach is applied to a 3D truss bridge and full-sized car model. The results correspond well to the experiment results obtained in the previous studies.
This research evaluates local structural conditions of RC columns of viaducts during earthquakes using acceleration measurement data. During strong earthquakes, the stiffness of RC columns reduces more severely during loading time steps than unloading time steps. The stiffness reduction from the unloading time steps to the loading time steps is evaluated as a damage indicator of the columns. A structural parameter identification method is first improved to identify loading and unloading stiffness separately. Then, the method of extracting loading and the unloading time steps are described. The proposed method is applied to a nonlinear SDOF model and a nonlinear viaduct model. Finally, the method is applied to the data sets of a large-scale RC column experiment conducted at E-Defense.
This paper discusses the effect of parameter determination in the structure system identification with respect to the accuracy and the robustness of identification. Structural characteristic of a FE model of an arch bridge is identified by three output-only identification methods, the eigensystem realization algorithm (ERA), the ERA with data correlation (ERA/DC) and the stochastic subspace identification (SSI), with changing parameters in the process. The accuracy and the robustness of each method are evaluated by comparing the identified characteristics with the FE model parameter and its eigenvalue analysis. Proper parameters have been derived from the analysis trials, and a new applied identification method has been proposed.
Many rubber bearings have been applied to railway steel and composite bridges. However, in the bridges where the rubber bearings were applied, it is concerned that the vertical displacement of the rubber bearings and resonant bearing vibration with the vibration of girder affect the train runnability such as running safety and riding comfort. This study aims to reveal the influences of vertical displacement behavior of rubber bearings on the train runnability. Firstly, vertical displacement behavior under train passage was obtained by measurements in an actual railway composite bridge. Based on the results, the influences on train runnability were discussed by simulation analyses considering vehicle-bridge interaction at 27 railway steel and composite bridges.
This study is aimed at verifying the applicability of acoustic measurement to the detection of resonant frequencies of local vibrational modes of steel girder bridges for the efficient and quantitative structural condition assessment. Basic experiment using a girder specimen was conducted. It was firstly shown that the peak frequencies of local vibrational modes could be detected from the frequency spectra of hit sound of the specimen. In addition, the condition changes at bolt joints between the girder and the stiffner, which simulated typical damages in the girder bridges, could also be recognized by the resonant frequency changes that were detected by acoustic data. From those results, the acoustic data acquisition was expected to be applicable to realize efficient and quantitative maintainance of existing bridges.
During a scenario earthquake with MW 9.0 along the Nankai Trough, not only strong motion but also huge tsunami is predicted in Suruga Bay area, Shizuoka Prefecture, Japan. Reliable estimation of difficult time during the earthquake in the areas is required to clarify tsunami evacuation. In this study, accuracy of the method to estimate difficult time for tsunami evacuation was investigated quantitatively at permanent station sites for strong motion observation with very high density in the focal area. The results indicates that the methods based on temporary earthquake observation or microtremor measurement in tsunami attack area lead to reliable estimation of difficult times for evacuation.
The spectrum-matched uni-directional accelograms are generally used to assess the seismic performance of regular bridge structures. However, since actual earthquakes are of bi-directional nature in horizontal components, performance assessment with spectrum-matched bi-directional accelerograms is regarded as advantageous. In this study, a procedure to synthesize spectrum-matched bi-directional acceleroograms from a spectrum-matched uni-directional accelerogram and its Hilbert transform by specifying the ellipitical component of poralization is proposed. Moreover, in order to examine the nature of the synthesized acclerograms, the response of bi-directional nonlinear elasto-plastic dynamic model with a single mass is investigated. As the result, it is found out that the influence of the ellipitical component of poralization on the nonlinear response can be computed with the proposed accelerograms.
When the Great Hanshin-Awaji Earthquake hit, some shield tunnels for telecommunication cable thrusted into vertical shafts, and water leakage occurred. Telecommunication cable tunnels, the most important facilities that have a large amount of cables in the urban area, should not get any damage that interrupt communication service by natural disasters such as earthquake. In this paper, we propose an estimation method and countermeasure against thrusting of a constructed shield tunnel. This estimation method uses vertical shaft's boring data, and this method is simple. This method is verified by the real damage of the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake. The countermeasure, on the other hand, is to install concrete base to drain pit, and it is economical and harmless to cable.
The tall noise barrier recently installed on Shinkansen structures has a low natural frequency that produces significant response amplification during earthquakes. The aim of this study is to understand the dynamic response characteristics of tall noise barriers and to establish its seismic design method. As the results of onsite measurements and numerical analyses, the seismic response of noise barriers decrease by 20-50% due to the interaction effect between noise barriers and structures, and it increases by 10-35% due to the rotation movement of structure. Finally, practical seismic design methods which take the effect of elastic natural frequency of structures, the interaction of structures and the rotation movement into account were proposed.
Displacement of RC column is strongly effected base rotation induced by pullout of longitudinal bar from footing. To evaluate the effect of pullout, experimental data of full-scale RC columns (C1-1 and C1-5) by shake table test is summarized. Pullout at base contributes about 30% to the column displacement. Analysis was conducted to make clear the mechanism of pullout, in which analysis considering bar-to-bar reduction with the redefined reduction coefficient on bond stress has well reappeared the experiment. It is clarified that tri-layer and bi-layer reinforcement of C1-1 and C1-5 contribute to the bar-to-bar reduction influence leading to greater strain of main bar and pullout.
Following the previous investigations, this paper presents a further study on developing two kinds of high-performance seismic damper, namely Buckling Restrained Rippled Plate damper (BRRP) and Rippled Plate-Buckling Restrained Braces (RP-BRB). In order to facilitate the design process of BRRP/RP-BRB, the following three subjects are investigated: (1) the optimum proportioning of the rippled core plates, (2) the proper gap between the core plate and the restraining plates to avoid the so-called blocking phenomenon and (3) a simplified restoring force characteristics of the dampers.
As a way of performing rational aseismic retrofitting for RC bridge piers whose rebars are round, we proposed a technique for unbonded the axial rebars, which can be done when RC concrete lining is conducted. It was clarified that the unbonded retrofitting did not inhibit the rocking behavior of the existing round rebars. This study proposes an evaluation method for a seismic retrofitting design for existing RC bridge piers, in which round rebar reinforcement was used. The rocking behavior of the existing round rebars was used in the proposed unbonded retrofitting. The studied evaluation method was based on the rotational angle at the base of the bridge pier, which corresponds to the allowable elongation of the rebars installed in the axial direction.
Bridge restrainers should be installed to prevent bridge girders from slipping down from superior of piers when a large earthquake occurs. The design load is determined by only deadweight of the bridge girder. Also, collision velocity and cushioning effect of rubbers are not considered in the design load. Weight-drop tests are often conducted to evaluate experimentally the dynamic performance of bridge restrainers. However, the weights used in the tests are very small as compared with the weights of bridges. So, authors developed weight drop device with large masses, and researched the effects of the load response under large weight difference. As a result, it is presented peak loads are increased as rise of strain energy due to the increase the collision velocity and weight.
Since the Hanshin-Awaji Earthquake Disaster, assuming the safe horizontal force during an earthquake has increased when designing bridges. When using metal bearings on a bridge, it has become difficult to design fixed bearings that corresponds to intensive horizontal force. Therefore, dispersing rubber bearing is commonly used these days. Railway bridges must maintain train's running quality, so we must consider the vertical displacement on the rail when designing the rubber bearing. It is essential to understand the influence of the rubber bearing's compression stiffness on the train's running quality. In this paper, we will examine the current formula's suitability of the constant compression stiffness and understand the basic quality of the compression stiffness so we can offer an accurate calculation formula.
It is important to clarify the test protocol for the rubber bearing and the evaluation method of the limit state based on the test. More than 100 laminated rubber bearings manufactured recently in Japan were tested under the cyclic loading. It is found that the ultimate shear strain varies widely from 160% to 450% with dependence on the secondary shape factor of the rubber bearings. An effect of rupture mode in the rubber bearing on the ultimate shear strain should be also studied, to improve the reliability of the design shear strain limit.
Sliding isolation systems consists of two components; frictional isolators that support the vertical load and absorb the seismic energy, and rubber bearings that generate the horizontal restoring force. Since the restoring force of frictional isolators depends on the frictional coefficient and the vertical load, the design of frictional isolation systems have low flexibility. To improve the design flexibility, slideing isolation systems with multi-frictional plates have been developed. In order to verify the fundamental and horizontal bidirectional behavior, the shake table tests were conducted. Base of the experimental results, the isolation systems show the stable frictional force in multiples of the number of frictional plates even in bidirectional response.
In order to find out the characteristic of force impacting on bridge girder, the steady flow combined with solitary wave experiment was carried out with a bridge girder model. As a result of the standard case (prototype: 7m/s-steady flow, 5m-solitary wave), the measured maximum horizontal force of steady flow combined with solitary wave on bridge girder by force transducer becomes 3.4 times to the measured horizontal force of the case only using steady flow. Besides, measured maximum vertical force of steady flow combined with solitary wave is slight with a uplift force of 1.3N on bridge girder, because the vertical force of the case only using steady flow is a strong downward force of -28.7N.
Concentrating on the horizontal force produced when the solitary wave impacts on the bridge girder, plural pressure gauges are set around the girder model; the correlation between the wave pressure and the horizontal force and further the variation of horizontal force together with the change of girder position are evaluated.As a consequence, the wave pressure generated in the front of girder is increased with the girder position approaching to the still water level. On the contrary, it is found that the total horizontal force keep the same value in different girder positions.
In this study, the structure of fluctuating surface pressure acting on a fixed circular cylinder was investigated by wind tunnel tests and computational fluid dynamics. Examinations of effects of the aspect ratio of the model gives to fluctuating surface pressure acting on a fixed circular cylinder also were carried out. Moreover, effect of boundary conditions of side walls for CFD on fluctuating surface pressure on a fixed circular cylinder were investigated. As results of this study, it was found that the spacial correlation of fluctuating pressure on a fixed circular cylinder was affected by aspect ratio of the model. POD nalysis indicated that the fluctuating surface pressure acting on a circular cylinder had symmetric and asymmetric mode shapes along the cylinder axis.
The basic characteristics of ground effects in aerodynamic force acting on a photovoltaic panel in shear flow were studied based on the measurements in a grid generated turbulent flow and past measurements in shear flows. The aerodynamic force coefficients of a two-dimensional flat plate model were measured in a wind tunnel with varied height and angle of attack. The effects of turbulence were similar in both the grid generated flow and the shear flows. The effects of shear were more apparent in wind force coefficients that is the coefficient of the force component normal to the plate rather than moment coefficients. The wind force coefficents became smaller near the ground, but the effects were weakened by the existence of wind shear.
This study is intended to investigate traffic effect on the aerodynamic stability of bridge deck. Wind tunnel tests have been conducted to test 3 different scaled bridge section models with vehicle models arranged on the bridge decks considering different types of traffic flows. The influence of vehicles of different traffic flows under cross wind on the aerodynamic performance of the bridges with the reduced wind velocity are investigated based on the experimental results. By comparing the measured results, the influence of vehicles on the aerodynamic stability of the bridge is overall not significant except some large vehicle and multiple arrangement cases.
Aerodynamic control methods for rain-wind-induced vibration (RWIV) have been developed so far. However, it is pointed out that these methods are still defective. For example, indented surface type is effective for RWIV but not for dry galloping (DG). Therefore, it is urgent to develop an effective countermeasure which can be applied for both RWIV and DG. In this study, responses of cables with spiral protuberances together with smooth surface, parallel protuberances and indented surface are examined in rain and dry conditions. The results reaffirmed that RWIV and DG only occurred in specific conditions and limited vibrations still appeared in indented surface and parallel protuberances. More importantly, the test indicated that the spiral protuberance with 4, 6 or 12 fillets at certain winding angle and pitch can mitigate totally RWIV and DG compared to indented surface and parallel protuberance types.
This paper investigates the transient lift forces induced by traversing a sharp-edged gust for three structural sections: thin airfoil, flat plate and square by dynamic wind tunnel experiment. Wavelet analysis is applied to remove the noise. Transient lifts are characterized by equivalent Küssner functions. They are gained respectively for the thin airfoil and the flat plate. The overshoot of lift is observed for these two structures.
Stress concentration of the bridge wire specimens with artificial pits were studied by experiments and FEM analysis. Two typical pit shapes were studied : round shape and triangle shape. The stress concentration of the triangle pit and the round pit was obtained by strain gauge measurement and 3D FEM analysis. Both methods agreed very well. Stress concentration factors were calculated for different pit shapes and sizes by FEM. The stress concentration factor of the triangle pit is largest followed by the the round pit. The narrower and deeper pit produces the larger stress concentration factors.
The study analyzes the impact that bridge inspection expenses with close visual technique have on municipalities' finance and verifies measure for promoting efficiency of their ongoing bridge inspections. It clarifies that the annual expences of bridge inspection operations by majority of municipalities surpass their mean bridge maintenance expenditures for the past 5 years. Also it shows that measure called collective ordering has the effect to the efficiency of an order procedure and supervision duties, but that just has a small effect to the cost reduction. While their bridge inspection operations pay for themselves, their challenges are how to efficietly implement the bridge inspection operations given a fiscal constraint.
Stress measurements of the newly built Koubo dam gates 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 are compared with ordinary design calculation values and FEM analysis values. Initial imperfection in the direction of the trunnion pin axis and shearing stiffness of the trunnion girder are quantitatively examined concerning the influence to the stress distribution of the arm. Furthermore, the influence on the load bearing ability of the unusual stress distribution caused by the imperfection is investigated by nonlinear FEM analyses considering future corrosion deterioration.
In this paper, an experimental study was carried out to investigate the remaining performance of frictional high strength bolted joints in an existing weathering steel bridge used for thirty years. Bolt axial forces, slip coefficients and slip strengths were measured for the real bolted joint specimens cut from the bridge to carry out a slip test and a bolt calibration test. The results of these tests showed that remaining bolt axial forces of many bolts were less than the design bolt axial force but the slip coefficients were more than the design value. Therefore the tests found the slip strength of all joints remained the design strength.
The heavy-duty coating has been applied to the steel members of the Honshu-Shikoku Bridges. The preventive maintenance for coating, which is timely repainted only surface coat and middle coat, was adopted, and the deterioration prediction of paint film was conducted to decide the repainting period. As a result of outdoor weathering test, it was found that the weather resistance performance of paint film is higher than that of previous repainting plan, and the high accuracy deterioration prediction method was required in order to judge a timing of the starting for repainting. In this paper, the development of the deterioration prediction method for heavy-duty coating considering the dispersion of the reduction rate of thickness and the remaining thickness of paint film is described.
In this study, a characteristic of residual axial force for corroded high-strength bolts was investigated. Corroded bolts cut from a steel bridge were used for the measurement of thickness reduction and residual axial force. The experimental results showed the residual axial force has a good correlation with the summation of thickness reduction. An FE analysis examined the effect of the corroded shape of bolts on the residual axial force. The analytical results revealed that the effect of corroded shapes on the residual axial force can be considered by the thickness reduction near the washer.
The one-sided plate bonding method, which can be done in a short time and does not affect traffic flow, has been proposed for repairing the corrosion on the orthotropic steel deck plate. Its effectiveness and the design method of required thickness of patch plates have been studied with the loading tests and FE-analysis. It's known that the fatigue debonding phenomenon might occurs under the repetitive loading, and it is necessary to study about that phenomenon in order to develop the patch plate repair method. In this paper, the debonding of the patcth plate on the orthotropic steel deck plate has been evaluated by the fatigue wheel loading tests and FE-analysis with the real sized specimen and by the fatigue bending tests. As the results, the appropriate edge position of the patch plate on the orthotropic steel deck was proposed.