When a continuous PC rigid frame bridge is subjected to fault displacements, response such as deflection, curvature, moments and so on are obtained differently if torsional rigidity is evaluated differently. Effects of torsion have not been considered strictly in seismic design code, therefore the evaluation of torsional rigidity is not rational. This paper presents the results of push over analysis of a continuous PC rigid frame bridge subjected to fault displacements in transverse direction, and clarifies the effect of evaluation of torsional rigidity on seismic performance of bridges. The necessity of adequate evaluation of torsional rigidity is discussed using moment torsion correlation curves.

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In this paper, several un-stiffened thick walled steel piers were analyzed to investigate high local strain in welded joints that triggered extremely low cycle fatigue failure. The local strain range at weld toe was correlated with the nominal strain range in effective failure length obtained by beam model analysis. Based on the local strain estimated by the nominal strain with the correlation, extremely low cycle fatigue assessment was carried out. It was shown that the local strain approach based on beam model analysis gave a safe side fatigue assessment result.

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The present study aims at investigating the initiation mechanism of ductile cracks, which is the first step of brittle fracture, occurred in steel bridge piers with thick-walled sections, in order to develop a seismic evaluation procedure for steel structures considering the evaluation of ductile crack initiation. For this purpose, a total of nine steel columns with small width-thickness ratios were tested under cyclic loading. It is found that ductile cracks occurred at the column base in all the specimens regardless of cyclic loading histories subjected. Moreover, by performing elaborate analysis using shell elements and fiber analysis using beam elements, it’s found that there exists a difference in the strain distribution at the point of crack initiation, and a factor accounting for the effect of structural details should be introduced in the fiber analysis.

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Although bearings and restrainers have been included in seismic response analysis of bridges, effect of failure of those structural components has not yet been fully analyzed. This paper presents an analysis of a 3-span simply supported bridge which is supported by elastomeric bearings. Steel plate type restrainers or PC strand restrainers are accommodated between decks. It is shown from the analysis that bearings fail progressively from a bearing located at one of the extreme edges due to rotation of decks. It is also shown that design concept to evaluate demand of bearings and unseating prevention devices by simply dividing the total lateral force by number of devices tends to underestimate real demand.

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The present study discusses the effects of a steel bearing performance on bridge superstructure response during a strong ground motion. For this purpose, a hybrid seismic response experiment for a steel bearing is conducted. As a result, a slip-type hysteresis is identified for bridge axis and transverse directions, respectively. In this respect, a slip mode as well as a stiffness increase are observed due to existence of space around the pin. Also, the degree of superstructure response is affected by a slip-type hysteresis, particularly in the bridge axis direction.

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Authors have shown the superiority using the low friction sliding bearing- support (LFSBS) for the continuous girder bridge by the seismic response analysis and shake table test for small steel girder bridge model. This paper inspects the validity of this system by the seismic response analysis for existing three span continuous steel girder bridge with seven different bearing supports conditions. Accelerations, displacements, bending moments and curvatures are calculated and compared each other. It became clear again that in the bridge with LFSBS piers vibrate independently from girder, and curvature at the bottom of the pier becomes very small compared to those of the ordinal existing support type bridge. The effect of damper installed between end of the girder and abutment to reduce the large displacement of the girder is also clarified. The use of the damper has no influence for the response of the pier.

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It is verified that a bridge with seismic isolation foundations has a significant positive effect in decreasing responses during earthquakes by model experiments and dynamic analyses. In this study, the effects of bilateral excitation and vertical excitation on a 4-span Rahmen-bridge with sliding type seismic isolation foundations are investagted by nonlinear dynamic analysis. As a result, bilateral excitation and vertical excitation affect the vibration behavior of the isolator and increase the response of the bridge.

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The seismic performance upgrading effects for steel bridge structures by introducing energy-dissipation members are investigated in this paper. The energy-dissipation members concerned in the present study are shear panel dampers and buckling-restrained braces, which dissipate seismic energy through metallic yielding. This investigation is divided into two parts: (1) an introduction of design details and modeling for energy-dissipation members; (2) a parametric study on seismic responses of various frame-type bridge piers with energy-dissipation members. Three parameters, the strength ratio, stiffness ratio, and displacement ratio, are identified as design criteria to investigate the performance of bridge structures with the energy-dissipation members. Significant seismic performance upgrading effects have been found numerically. The results show that the parameters can be used as key parameters in unified design of such energy-dissipation members.

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An Impact Mass Damper (IMD) is a simple damping device which consists of a weight and a cushion attached on a tower. It utilizes energy dissipation due to collision between the weight and the cushion on the tower. Considering damping capacity of the IMD depends on the collision, the impact force caused by collision cannot be neglected and it may have a bad effect on habitability of the tower. This paper proposes the new IMD idea which has the lower impact force and the enough damping capacity to suppress the harmful vibration, by investigating the vibration characteristics of the cushion.

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This paper presents an application of shear dampers made of low yield steel to improve the energy dissipation capacity and to reduce the seismic responses of steel bridge bearings under the earthquake loads. The program is to investigate the cyclic shear behavior of shear dampers to use for hysteretic devices of bridge bearings and to control the seismic displacement of bridges in the longitudinal and transverse directions of the bridge axis. The shear damper is in the category of function-separated bearing system. Total of nine different types of specimens are tested under the cyclic loadings. The optimum shear dampers are discussed to increase the seismic performance of shear-type seismic bearing device for steel bridges.

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Perturbation method was used to investigate the nonlinear sloshing motion in a cylindrical circular tank in response to forced horizontal oscillation. First three terms in perturbation expansion were adopted in the present paper. When the ratio of wave height to water depth is more smaller than 0.3, the numerical results are in agreement with the experimental data indicating that the fluid response, both in terms of wave height and hydrodynamic force. According to the theoretical expression deduced from perturbation method in this paper, the time required for numerical calculation is extremely short.

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Usually, the bridge used to traverse rivers, channels and straits is a fixed type. However in cases where the seabed of a thick layer of soft ground, a floating bridge is often more suited than a fixed bridge. This study proposed a system for anchoring a floating bridge with submarine cable to create a floating bridge suitable for places where ground subsidence occurs. Using an experimental tank, the bridge’s motion characteristics while exposed to waves and seismic were tested and a numerical analysis was performed.
A relatively strong consistency was found between our analyses of wave motion and seismic response of floating bridges taking account of anchorage characteristics, and the test results. It was found that the floating bridge with submarine cable system was highly suitable for locations where there was significant ground subsidence.

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This paper describes a serious failure of 37-ton Tainter gate in Japan and presents its failure re-investigation, where the major characteristics of static structural strength and self-excited vibration are addressed with the aid of current FEM high technologies and our theoretical calculations developed for the 87-ton Tainter-gate failure at Folsom dam in California. The Tainter-gate failure occurred on July 2nd 1967 at W Dam, constructed at the upstream of Yura River in Kyoto Prefecture in Japan. The failure investigation at that time concluded that the radial strut structure was not high enough in strength for the hydrostatic load to induce the serious in-ward buckling failure of the main radial struts. In the present study, FEM simulations were made to address that the gate failure could not take place, caused only by the static hydraulic load. Subsequently, the theoretical calculations developed for the Folsom Tainter-gate failure was incorporated into FEM simulations to address that W gate also induced the coupled-mode violent self-excited vibration at its incipient failure, while the gate was being closed at small gate openings, closely similar as on the Folsom gate failure.

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Shaking table tests were conducted for a rectangular water tank filled to its capacity in order to recognize the overflow behavior with sloshing. Fundamental sloshing phenomena during strong earthquake motion in 2003 off Tokachi were found out such as wave heights, dynamic water pressure, overflow of water and complex wave surface using an image-based measurement. Numerical analyses of free surface flow using volume of fluid method were carried out on these sloshing tests. The analyses results agreed well with the tests results in time histories of wave heights, overflow of water and wave shape. Realistic estimation methods for overflow of water during earthquake were proposed through these studies.

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In seismic wave that includes long wave length, oil storage tanks have been badly damaged to floating roof unit at rare intervals. We consider fluid structure interaction problem (FSI) in which content liquid of the tank have sloshing vibration with the floating roof during the ground motion. Content liquid is followed by Navier-Stokes Fluid in general points of view. However the sloshing problem can be efficiently and practically solved using linear potential-based formulation with finite element method. This paper shows the efficiency of this formulation in comparison with experiment test result and at same time, is raising some points that are not adapted with the real phenomenon.

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Flow-induced vibration often gives structures the big damages and causes serious accidents. So, the study on mechanism of flow-induced vibration is very important. Structures have three-dimensional shape with sharp edge in span-wise direction. We investigated 3-dimensional flow and detailed flow structure around an oscillatory circular cylinder with a finite span-wise length by numerical simulation. As a result, the vortex excitation appears for the cylinder with short span-length; the aspect ratio, AR=2.5, since the fluctuating amplitude of lift force and the base pressure is almost uniform in the whole span except the tip-end, and the exciting energy is large. For the cylinder with long span-length, AR=8.0, the exciting energy becomes small, approaching to the base, because vortex-formation region is far away from cylinder. However, the flow around the tip-end of the cylinders with the aspect ratio of 2.5, 5.0 and 8.0, presents the almost same flow pattern.

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The spatial correlation of fluctuating lift forces plays an important role in the buffeting resonse analysis for horizontally long structures. Some recent researchers have pointed out that the spatial correlation scale of the fluctuating lift force acting on bluff bodies is much larger than that of the fluctuating velocity of the approaching flow. To investigate the forming process of the spatial correlation of fluctuating lift forces, the transmission of the weak periodic disturbance generated artifically near the stagnation point of thin plates was examined through the measurements of the surface pressure. As a result of this study, it was clarified that the strength and the frequency of the disturbance did not affect the size of the area including the pressure fluctuation caused by the disturbance, and the width of the area propagated the disturbance changes in proportion to the length of the separation bubble.

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Steel box girder bridges have been often used for the bridge with longer span length than 100m. The possibility of occurrence of aerodynamic vibration is increasing with increment of span length. Up to now, in order to suppress the aerodynamic vibrations, additional aerodynamic devices such as flap and skirt have been adopted. However, since these devices are not structural members, additional installation cost and maintenance cost for long term usage are needed. If the aerodynamic instability of the bridge is improved without such additional devices, the construction cost and maintenance cost of the bridge will be reduced. In the present research, it was investigated whether the aerodynamic vibrations of both vortex-excited vibration and galloping could be suppressed by only changing bottom corner shape of the steel box girder without using additional aerodynamic devices.

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Flutter stabilization is one of the most important engineering problems in wind-resistant design of long-span bridges, particularly constructed in a large strait crossing project. Previous investigations have shown 2-box girder sections get superior stability performances against flutter through various attachments. However the mechanism of flutter stabilization has not been cleared thoroughly. In this study, the aerodynamic characteristics and the flutter stability performance of 2-box girder sections with attachments are examined by wind tunnel tests and complex eigen value analyses. Tested attachment sets are combinations of three typical devices of the center barrier, the parapets and the rails for a maintenance carrier. The mechanism of stabilization in each attachment set is explained from the change of important components in unsteady aerodynamic derivatives.

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In recent years, innovation of the bridge technology in Japan is remarkable. Especially, the number of bridge construction of the cable-stayed bridge is increasing every year from short span bridge less than 100m to long span bridge longer than 800m, because the cable-stayed bridge has both structural and aesthetic advantages. However, since the cable-stayed bridge has lower stiffness, the vibration problem easily occurs in the wind that induces vortex-excited vibration, galloping and flutter. Until now, in the girder cross section with open deck section and two-box girder, experimental investigations have been carried out about the influence of shape of fairing and shape of box girder on aerodynamic instability. But there are few examples of investigation about influence of cavity under deck of two-box girder on aerodynamic instability. Therefore, the present paper treats the influence of cavity under deck of two-box girder bridge on aerodynamic instability.

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The static and dynamic wind-induced instability analyses of super long-span cable-stayed bridges with main span length of 1200～1800m are presented in this paper. Firstly, the static aeroelastic behaviors of bridges against displacement-dependent wind load are investigated by three-dimension geometrical nonlinear analysis. Secondly, the free vibration and flutter analyses are carried out. The comparisons of structural dynamic properties between cable-stayed and suspension bridges are discussed and the impact of the cable vibration effect on the dynamic characteristics and the flutter behavior is studied. The analytical results show that static instability controls the dimension of the girder and the safety against both static and dynamic instabilities can be ensured even with main span length of 1800m.

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A multiple-span suspension bridge has been often proposed for strait crossings because of the advantage of reducing huge intermediate anchorages. However, it has a disadvantage of large static deflection and therefore a countermeasure was proposed such as stiffer intermediate towers. The characteristics of the static deflection have been studied by some researchers, however a limited number of studies on that aerodynamics have been done so far. In this study, flutter characteristics of a 4-span suspension bridge with main span length of 2,000 - 4,000m were investigated by flutter analysis. The results showed that its flutter speed is lower than that of a 3-span with the same center-span length, and that the side-span length of a 4-span suspension bridge affects the flutter speed less than that of a 3-span suspension bridge.

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In order to consider the applicability of visual inspection to bridges maintenance, we surveyed cracks and steel bar corrosion of RC bridges near Sea of Japan in Aomori prefecture. The surveyed results were compared with the chloride ion densities near the steel bars. Through the survey, the following points have been revealed: 1) There was a case that steel bar corroded surrounding by high density chloride ion, while there was no crack on the surface of the concrete. Therefore, visual inspection did not give sufficient information about steel bars in RC bridges. 2) But in case few cracks were found on the surface of the concrete, checking increase of cracks might effective to make planning maintenance, because average intervals of cracks calculated by grid method, correlated well with chloride ion density near the steel bars. 3) Damage grades calculated from cracks conditions correlated with degree of steel bar corrosion ranked by the standard specification for concrete structures.

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Evaluation of bridge slab deterioration and its degradation prediction based on actual inspection data are dealt with in this paper. To evaluate the slab deterioration, the effects of traffic loads, salt damage, freezing and thawing and so on, are the elements of evaluation. Especially, deterioration of the slab in a cold region is changing with a freezing and thawing action or enlargement of vehicles. Inspection data on the slab may include the effect of those elements and be useful to analyze the magnitude of the effects. Depending upon the analytical results using actual inspection data, overall prediction method of deterioration is investigated and its prediction will be utilized in Bridge Management System (BMS).

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A reinforcement system is developed for aged RC telecommunication manholes which are unavoidable a sustainable use. Essential reinforcement parts of an aged manhole are a periphery of circular entrance on the upper slab and corners between the slab and walls. These parts may be critical to bending moment by excessive live loads of automobiles. The system is composed of the round arc CFRP plate for the upper slab and resin concrete segments for the corners. The former is effective to increase stiffness of the manhole as well as the latter to increase strength. This paper shows verification of the system based on full-scale model tests and on 3D-FEM simulation analysis.

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Rubber bearings used in bridges are generally exposed to various environment conditions. It is usually known that the sunlight attacks rubber material, and causes it to entirely lose its elasticity and become sticky. In order to obtain the knowledge of the long-term performance of the ultraviolet exposed rubber products, the effect of ultraviolet irradiation on surface rubber of bridge rubber bearing has been examined through accelerated aging tests. Four kinds of rubber materials normally used were subjected to ultraviolet irradiation for a period up to 2 months. The changes in mechanical properties were investigated with different pre-strains. Besides, the influences of the amount of carbon black on the ultraviolet stability of natural rubber (NR) were evaluated. Finally, the long-term performance of surface rubber was estimated in consideration of the location.

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The pre-stressing method using high tensile strength steel plate can reduce both dead-load and live-load stress, by pre-stressing and by giving additional stiffness. In addition, the anchor detail of reinforcing steel plate to the reinforced beam can be much simpler than that of Outer Cable Method, because the common high-tension bolt joint can be used for the anchor structure. This method had been already confirmed to be so effective as predicted by the theory, through application work in existing bridges. In this study, as an application of this method to new bridges, we try to extend the span of H-beam bridge and reduce either the depth or the number of main girder by applying the Steel Plate Pre-stressing Method.

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There are considerable effects of temperature on strain measurement of civil structures such as highway and railway bridges. This temperature effect poses a great obstacle in damage identification and structural health monitoring (SHM) of these structures. In this paper correlation between temperature distribution and strain at bridge structure has been studied. Temperature effect has been modeled by using Multiple Regression and Neural Networks (NN) analysis based on temperature and strain distribution measured at a bridge model. A new compensation method of temperature effects on strain measurement has been proposed which can reduce the measurement error to about 5% or less.

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A new update of the existing bridge is difficult because of the reduction of the budget of the central government finance by an economic long slump. It is important to be going to attempt making of the existing bridge long-lived with an appropriate of maintenance in the future. Therefore, it is necessary to develop the simple investigation technology to be enforceable of the health evaluation of the deteriorated bridge in year of passing promptly and easily. The purpose of this paper is to propose the technique for simply health evaluation by using the measurement strain and the measurement natural frequency for the existing steel composite girder bridge that movable shoe is restricted and doesn’t move horizontally.

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The weathering steel has a unique property of preventing rust by rust, and using unpainted weathering steel is important to reduce the life cycle cost of infrastructure. The following condition for unpained weathering steel should be satisfied to generate a protective rust on the surface of the steel : maximum amount of marine salts density is less than 0.05mdd (mg/dm²/day). However a state of corrosion is different in the part of the bridge. Accordingly, evaluation for quantity of marine salt is needed at each part of the bridge. This paper discusses a estimation of marine salt around section of the bridge by comparison between numerical result and measurement of marine salt and adhering salt on surface of girder.

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This paper proposed an evaluation model of seismic damage loss (direct loss and indirect loss) of a multi-hinge structure which has a complicated damage process like a railway viaduct. In this model, structural damage event analysis with push-over nonlinear analysis is carried out, and systematical seismic loss evaluation, introducing the damage flag (delta variable), is performed. Using this model, we calculated the seismic damage loss of two different structures designed based on different design-criteria. As a result, quantitive differences in the damage loss between the two structures became clear.

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Recently, several types of fatigue cracks were found in diaphragm details inside steel pier beam just under bridge girder support details. Most of those fatigue cracks initiate from the diaphragm-beam flange weld, especially at the coped slit for the longitudinal ribs passing through the diaphragm and below the ends of welded cover plates (shoe plates). This study investigates the mechanism of the fatigue cracking through the stress evaluation by loading test with a real size specimen and FEM analyses, and examines several retrofit methods.

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Deterioration of existing PC pipeline systems could result in water leakage or dropping of pressure. In most cases, such non-destructive tests as a water leak detection method or a ground probing radar method are applied to identify leakage location in pipeline. Although these methods are effective for evaluation of limited sections, further technical improvement is necessary for wide-range and long-term measurements for maintenance of the existing pipelines. In this study, water-leak evaluation by Acoustic emission (AE) method and the material physical properties evaluation have been conducted at the existing PC pipeline. AE behaviors at leaked section of the pipeline are different from those of sound portion. AE activity in water-leak section is high, and water leak and environmental noise can be distinguished by AE parameter analysis. A relation between AE rate and inner water pressure is analyzed by the rate process theory. It is realized that AE activity is closely associated with to water leakage in water-leakaged pipeline.

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As for the asset management of existing infrastructures, making a decision objectively for repair timings is an important issue, and the statistic deterioration prediction based-upon visual inspection data evaluated by multi-staged ratings will be one of the efficient way. However, most of infrastructure managers do not possess enough inspection data to carry out the statistic deterioration prediction with high accuracy. This study addresses a Bayesian updating methodology which can provides the prior estimates of the deterioration process by the expert’s subjective and empirical judgments at the early stages, and revises them sequentially based on the additional data obtained through inspections. The proposed method is applied to the actual visual inspection data for painting deterioration of steel girders to verify the effects of the prior subjective information to Bayesian updating results of deterioration prediction.

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In order to investigate the strength deterioration of thin cylindrical shell structures caused by corrosion, bending buckling tests were conducted on electric power poles. Before the loading tests, surface irregularities were measured using a 3-dimensional portable measurement system. The following findings were obtained from the test results: (1) The remaining strength of corroded thin cylindrical shells depends on the corroded area, and the remaining strength decreases remarkably when the corroded area is larger than buckling region. (2) It is appropriate to evaluate the remaining bending buckling strength of corroded thin cylindrical shells by examining the remaining thickness in the region of buckling.

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This paper presents an implementation of localization(i.e., determination of positions) and time synchronization methods for sensor network. Relative positions between sensor nodes are estimated based on acoustic ranging through Inverse Delaunay Algorithm. Noise tolerant acoustic ranging algorithm that employs digital signal processing techniques is implemented in an off-the-shelf sensor platform (Mica2). Field experiment was conducted with 21 sensor nodes to evaluate the accuracy of the localization. Besides a time synchronization method between sensor nodes based on time stamp is developed. Experiments show that the shift of synchronization is under 2ms for 500Hz sampling.

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In recent years, the structure made of weathering steel has been paid attention concerning the life cycle cost. The Japan guideline describes the rules of the construction for the weathering steel bridge that the weathering steel is applicable in the region which is more than 5km from the coast of the Japan Sea. Many weathering steel bridges have been constructed in Shimane. However, the performance of the weathering steel in those bridges is not well traced.
The authors conducted the field study of performance on the weathering steels in Shimane. This paper is reported the results of our investigation into the corrosion condition from the point of view rust development.

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3D lazer scanners with motor-driven X-Y stage are often used to measure the surface roughness of corroded specimens. However, due to the limitations of these apparatuses, the specimen surfaces, such as upper surface, lower surface and side surfaces, must be measured indivisually by changing the locations of the specimen or the lazer scanner. Therefore, in order to generate the 3D numerical models of corroded specimens, it is necessary to unify these indivisual surface data sets. Herein, an accurate method is proposed to unify adjacent two indivisual surface data sets by utilizing the centers of three globes as benchmarks common to the two surfaces. The surface data of the globes measured by the lazer scanner can be used to identify their center locations accurately. The repetition of this procedure leads to the generation of a fully 3D-numerical model.

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In steel bridges, the corrosion damage occurs easily at sharp free edges of bottom flange, bolts, nuts and so on, because securing desired thickness of coating films is difficult at such locations. This study examined an accelerated exposure test and measured the thickness of the coating films to investigate corrosion resistant at different types of edge shapes. Test specimens were exposed to the accelerated corrosion environment conforming to Japanese Industrial Standards K5621 for 200 days for metallic coating and 400 days for paint coating. From the corrosion occurred at edges and the thicknesses of coating, anticorrosive performance of various coating systems was discussed. The paint coating system at the round edge had good performance compared with other shapes of edge. The metallic coating system also had good performance for all types of edge shapes.

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It is important to estimate corrosion environment of steel bridges for an appropriate corrosion prevention and maintenance program. Estimation of environment has heavily depended on insitu observation and many data have been collected. However, versatile numerical approaches to this problem have not fully been pursued yet. The objective of this work is to apply the method of computational fluid dynamics(CFD) to estimate the corrosion environment in a box-girder, where the boundary conditions are relatively well-defined and therefore numerical simulation is easily applicable. In the present analysis, water condensation on a girder-surface is considered by a simple but reasonable droplet modeling. The present CFD analyses rationally explain the relation between the inside and outside temperature and humidity, the location of condensation.

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Automated remote monitoring system would be effective for the management of infrastructures and high accurate structural identification is indispensable to recognize the level of structural deterioration by change of natural frequency. In this study, we developed the remote monitoring system by mobile communication system and AR model-based structural vibration-estimation method. The system was installed to the Kabashima Bridge, an existing steel langer truss bridge in service in Nagasaki. This paper shows the abstract of the system and long term bridge monitoring results.

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Moment resistance of timber joint is semi-empirically analyzed by considering the experimental results of single-bolt connection and the energy conservation principle. In the analysis, experimental load-slip response of single-bolt connection is approximated by exponential and bi-linear models. Verification of the proposed models is carried out through full scale test of semi-rigid joints that monotonically loaded by a pure moment. Wood specimens of Shorea obtusa and three different bolt arrangements are implemented in both steel-to-wood and wood-to-wood connections. Experimental results show bolt arrangement that has long distance along the grain between bolts gives high moment capacity, high ductility, and high rotational stiffness. Wood-to-wood connections have higher moment resistance and higher ultimate joint rotation than steel-to-wood connections, since wooden plates as side members in wood-to-wood connection are less stiff than steel plates and they allow more load redistribution among bolts during inelastic stage.

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Timber joints are one of the most important considerations in timber bridge design because they provide continuity to the members as well as strength and stability to the system. The connections may consist entirely of wood members but frequently involve the connection of wood to steel or other materials. This paper presents an experimental and analytical studies on bending behavior of prestressed laminated timber beam made of Japanese Cedar. The concept of prestressed laminated timber for bridge applications was developed in Canada. This bridge deck consist of lumber or glued laminated timber transversely posttensiond by high-strength steel bars anchored against steel bearing plates. In this paper, glued laminated timber longitudinally posttensioned by high-strength steel bars are proposed. The simplified bi-linear stress-strain relationships are assumed for japanese ceder, and the effect of joints on elasto-plastic deformation of prestressed laminated timber beam are investigated.

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The bending capacity and failure mode of glued-laminated timber beams with plural rib plates on tension sides are investigated. The three types of beams are manufactured and tested. All the beams have same width, depth and span length and also have one rib plate with same dimension on compression side of beam. They have one rib, two ribs and three ribs on tension side, respectively and the sum of thickness of ribs is the same as one rib type. The type of three ribs shows the most highly bending capacity and most moderate failure mode.

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In recent years various types of hybrid structures of steels and glulams such as steel-plate-inserted glulam-beams are adopted for timber road bridges. While experimental studies are typical methods to evaluate the load-carrying capacity of the hybrid structures, experiments have limitations of scale, time, money and so on. This is the reason why we hope development of numerical studies. In this study we show one of the elasto-plastic FEM analysis of steel-plate-inserted glulam-beams using free GPL-license FEM program CalculiX. We model the glulam and steel parts by isoparametric 8 node brick elements as orthotropic materials. We can show to a certain extent that the FEM modeling well evaluate the behavior of the hybrid beams within the range before the tension side glulam breaks.

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Many huge timber structures were constructed recently, because of protecting global environment and forests. Forest resources are ecological materials, and they should be used especially on public construction. A short road bridge utilized for regional forest resources is proposed in this paper. It is composed of coupled sawing lumber with large cross section and glued with each other. The model bridge based on this idea is introduced. Ultimate loading tests of coupled sawing lumber beams used on this bridge are carried out in order to confirm its ultimate performance. Loading test for real bridge was also carried out and reported.

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Recently, a large number of the timber bridges are constructed. The most of timber bridges are pedestrian bridges with short spanned length and mainly used a simple girder type. In these bridges, it is necessary to know its behavior for load distribution to increase the durability. However, the behavior of these bridges is not clearly clarified yet. The loading tests were performed to investigate the behavior of short spanned timber bridges. And the numerical analyses were carried out by changing material properties and boundary conditions of connection parts. The details of behavior were investigated, compared with results of lading test and numerical analysis. As a result, the tendency to the behavior of the timber bridge was able to be confirmed by combining some analysis conditions.

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Making the construction procedures of short span bridges more rational and economical, a new slab bridge system composed of steel square tubes was proposed. In the actual bridges, there are so many skewed bridges because of the site condition. So, applying the proposed bridge more widely, tests on skewed bridge were required. To clarify load transfer performance and ultimate strength of the skewed slab bridge composed of steel square tubes, loading test on the bridge structure with skew angles of 60° was conducted. Moreover, to make clear the difference between the skewed bridge and the straight bridge, FEM Analysis was also conducted. As the results of these investigations, it is confirmed that the skewed slab bridge composed of steel square tubes has sufficient strength and load transfer performance.

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On the next revision of design code for highway bridges, introduction of the partial factor design format as the international reliability-based design is being investigated. This paper aims to clarify reliability level of steel I-girder highway bridges designed by the current Japanese design code, and to calculate resistance factors. This paper involves selection of statistical parameters of live/dead load and resistance model, reliability analysis method, and calculation of the reliability indices. Focusing on flexural/shear capacity of steel I-girders, the reliability analysis is conducted for selected typical I-girders using statistical parameters based on the available literature.

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When hot dip galvanizing treated steel structures, a sudden temperature change is given, and unsteady thermal stress occurs in a member between a part doing a dip earlier and parts doing a dip later, and there is the case that thermal strains and crack accidents. In this paper, steel plates were soaked in melted zinc to reproduce the state of the temperature distribution in the material that had a big influence on thermal strains etc., and the temperature distribution is measured. Moreover, the temperature distribution is estimated by using the optimization technique analyzing it for the relation between the heat diffusivity and the heat transfer coefficient and steels thickness.

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