The aseismicity of a multi-spans highway bridge designed by Vietnam Specification is evaluated by dynamic response analysis according to Japan Specification. The bridge adopted in this study is located at Hanoi in Vietnam where is classified to a low moderate seismic zone based on the investigation. As to Level 1 earthquake, there is no damage in the bridge, i.e. the seismic performance of the bridge is also secured by Japan Specification. As to Level 2 earthquake, though girder's unseating is not calculated, the bridge pier is predicted to have damage due to the large rotation angle at the plastic hinge and the lack of the shear resistance of the pier.

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Presented in this paper is an analytical study on ultimate limit states of a long-span suspension bridge during large-scale earthquakes. Dynamic analyses incorporating collapses of structural members, as well as both geometric and material nonlinearities, were performed in order to simulate seismic behaviors until the ultimate limit states of the Akashi-kaikyo Bridge, the world-longest suspension bridge. For the analyses, increased site-specific large-scale earthquakes were applied in order to investigate the ultimate limit states. As a result, the seismic performance against greater than site-specific large-scale earthquakes and possible collapse processes reaching the ultimate limit state of the model bridge were verified.

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This study is aimed at seismic performance evaluation of steel continuous bridges with rigid superstructure-pier connections. For this purpose, two pushover analyses were carried out. The first analytical model was composed of beam elements. The second model was made up of beam elements and shell elements. Adopting this model, a few segments becoming ultimate state at an early stage consist of shell elements. As a result, the horizontal displacement corresponding to the maximum strength of the structure obtained by using this newer model is larger than conventional method. Therefore the proposed method can evaluate seismic performances of this structure more than previous method. Finally, out-of-plane deflections occuring at the corner are discussed.

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We have been developing a theoretical method of simulating deterministically the spatial variability of near field ground motions for the purpose of aseismic design and analysis of structures. This paper presents the characteristics of the temporal and spatial variability of near field ground motions, and the characteristics of the 3D nonlinear response of a steel truss bridge. The near field ground motions with large permanent movements due to a fault are simulated using the stiffness matrix method. The effects of the sedimentary layer and the depth of the upper edge of the fault upon the ground motions, and upon the nature of inelastic response of the steel truss bridge are examined. It is found that the seismic wave motions near a fault are quite complex and thickness of the sedimentary layer and spatial position strongly affects on the response behaviors of the steel truss bridge near the fault.

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When steel arch bridges are subjected to fault displacement, seismic performance and damaged mechanism of steel arch bridges have not become clear yet. This paper presents the results of pushover analyses and nonlinear dynamic analysis of half through steel arch bridge subjected to fault displacement in transverse and longitudinal directions, and clarifies the effect of fault displacement on the evaluation of seismic performance of half trough steel arch bridges. The analysis of half through steel arch bridge by the fault displacement obtained from the integration of a seismic wave was carried out, then followed the nonlinear dynamic analysis in order to investigate seismic performance of this bridge. The validity and effectively of a dynamic verification method for half through steel arch bridge subjected to the fault displacement was discussed.

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In this study, first, the nonlinear static analysis of a steel cable-stayed bridge subjected to enforced displacements were conducted and it was grasped that the differences of seismic performance by directions of fault displacement. Next, the nonlinear dynamic analysis of this bridge considering fault displacement was conducted and the results were compared with dynamic analysis considering only inertia force and static analysis. It was found that the static analysis and dynamic analysis considering only inertia force underestimate the sectional force and the necessity of the dynamic analysis considering fault displacement was verified.

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The paper presents experimental and analytical results of thick-walled steel columns subjected to cyclic loading and aims at developing a ductile failure evaluation method for the ductile crack initiation in the steel bridge pier. To this end, cyclic tests of nine steel columns were carried out to clarify the influences of material, section shape and loading histories on the ductile crack initiation. Moreover, by performing analysis using the shell element, strain behavior was clarified and damage indexes based on Miner law were established. It is found that compared with the experimental results, the presented method is of good accuracy in the evaluation of the ductile crack initiation.

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Ductile crack initiation is the first step of brittle fracture in steel bridge piers subjected to earthquake-induced cyclic loading. Therefore, seismic performance evaluation method considering ductile crack initiation is needed in order to prevent brittle fracture. The present study aims at developing an evaluation method for the prediction of ductile crack initiation due to large amplitude cyclic straining at the base and beam-column connection of steel bridge piers. By performing finite element analysis using shell elements, hysteretic plastic strain behavior is clarified. Moreover, by applying a damage index based on the Miner's law and the Manson-Coffin's law to the plastic strain history obtained from the analysis, ductile crack initiation is predicted and compared with that of the experiment.

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An investigation is made on how the coupling of bi-directional horizontal seismic excitations affects the ultimate behavior of thin-walled circular steel columns used as bridge piers. First, an instability criterion is derived to identify the ultimate limit state of columns under bi-directional horizontal loads. Then, an ultimate interaction curve expressed in terms of two horizontal restoring force components is derived based on the so-called pushover analysis. The accuracy of the proposed ultimate interaction curves is confirmed by carrying out an extensive materially and geometrically nonlinear dynamic analysis under various bi-directional seismic excitations. Finally, in view of the application to practical design, the derivation method of some partial safety factors is also discussed.

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Many over-road steel railway bridges of the metropolitan area have pillar form piers. However, there are few examples of researches on the evaluation of earthquake-resistance of the steel railway bridges having the pillar form piers till now. In this paper, we report the result of the fundamental examination of earthquake-behavior by the dynamic analysis, with parameter of rotary stiffness of pivot bearing, the lower lateral bracing and presence of brace members between the pillar form piers.

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Embedded Plastic Segment (EPS), which has been developped as a seismic retrofitting technique for existing steel bridge piers, can enhance the ductility with less increment in the ultimate strength of the column members. In this paper, the seismic performance of a viaduct of the total length 200m with 5 spans supported by the steel bridge piers with the EPS is analytically investigated. The effectiveness of the steel bridge piers with the EPS is revealed in comparison with a viaduct supported by concrete filled steel bridge piers. It is concluded that the EPS enables the reduction of the construction cost of piles and footing concrete and the enhancement of redundancy of the viaduct.

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Concrete-filled circular spiral steel tubes (CFST) were tested under cyclic lateral force and a constant axial load. The welded part of this steel tube form a spiral and the seam-welded part is thicker than the steel tube wall. The test results showed that filling in steel tube with concrete enhanced the loading capacity and ductility of the CFST, and the spiral-welded part had no influence on the tube's flexural behavior. It was confirmed that the evaluation of the seismic performance of CFSTs does not need to take the existence of a spiral-welded part into consideration, and the relationship between load and horizontal displacement of CFSTs can be evaluated based on current design specifications.

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CFT (Concrete Filled Steel Tubular members) has attracted much attention because of its structural superiority. However, the increase of weight by filling with concrete inside is one of problem associated with CFT. Thus in this study, to reduce the self-weight of CFT, CFDT (Concrete Filled Double-Skin Steel Tubular members) is proposed particularly for higher bridge piers. The purpose of this study is to clarify the influence of the thickness of outer and inner steel tubes on the bending characteristics by the cyclic loading test and the analysis. As a result, it is shown by the cyclic loading test that CFDT has higher bending strength and energy absorption than CFT of the same weight. CFDT without inner tube has sufficient bending strength, but after the crush of the concrete, its ductility declines like only outer tube. By the constraint effect of concrete, buckling of inner tube is prevented, so the thickness of inner tube can be thin. For reasonable structure, it is effective to make the outer tube thicker than inner tube.

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When dynamic analysis is conducted, reduction of torsianl rigidity is typically configured from tenth to twentyth part of initial rigidity. So influence of torsion is treated as unimportant on concrete structures. However, we think that influence of torsion should be appropriately considered in seismic design. Therefore, we conducted cyclic loading test for RC columns loaded by axial force, bending and torsion at the same time, and formulated the reduction of torsianl rigidity. Furthermore, nonlinear dynamic analysis using the proposed fomula of the reduction of torsional rigidity of RC columns was demonstrated for a RC framed structure.

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The bi-axial behavior due to three-dimensional motions of earthquake and the eccentricity of the structure is shown in structures at the earthquake. At first, we investigate the intensity of the sub-directional motion crossed to the strongest directional motions from some strong earthquake records. Then, we calculate the maximum inelastic response of eccentric reinforced concrete piers for bridges subjected to bi-directional motions expressed. As a result of this study, the intensity of the sub-directional motion is important in order to estmate the inelastic response and the damage of concrete piers.

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This paper investigates the effectiveness of the use of seismic isolation devices on the overall 3D seismic response of curved highway viaducts with an emphasis on expansion joints. Furthermore, an evaluation of the effectiveness of the use of cable restrainers is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using LRB supports combined with cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

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The spatial variability of the input ground motion at the supporting foundations plays a key role in the structural response of flexible long span bridges such as cable-stayed and suspension bridges, therefore the spatial variation effects should be included in the analysis and design of effective vibration control systems for such horizontally extended structures. The control of long-span bridges represents a challenging and unique problem, with many complexities in modelling, control design and implementation, since the control system should be designed not only to mitigate the dynamic component of the structural response but also to counteract the effects of the pseudo-static component of the response. The feasibility and efficiency of seismic control systems for the vibration control of cable-stayed bridges are investigated. The spatial variability effects of the ground motion in the analysis of seismically controlled long span bridges is considered based on the decomposition of the total structural response into a dynamic component and a pseudo-static component. The assumption of uniform earthquake motion along the entire bridge could be unrealistic for long span bridges since the differences in ground motion among different supports due to travelling seismic waves may result in quantitative and qualitative differences in seismic response as compared with those produced by uniform motion at all supports. Comparison of the seismic response of the controlled cable-stayed bridge due to non-uniform input of different wave propagation velocities with that due to uniform input demonstrates the importance of accounting for spatial variability of excitations.

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This paper presents a result of a series of general investigations into the damage control seismic design of steel bridges in which the objective of the performance is to preserve the function even after severe (level 2) earthquakes. To this end, it has been shown that one of the most efficient ways is to install energy dissipation devices in bridges, such as buckling-restrained braces (BRBs) or shear panel dampers (SPDs). In this paper, BRBs are selected. An idea of high-performance BRBs that is expected to withstand major earthquakes three times without being replaced is proposed, and their required demands are clarified. Furthermore a series of performance tests and analyses are carried out to verify the proposals.

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Since Hyougoken-nanbu Earthquake in 1995, improvement of seismic performance of structures comes to significant issues. Installing dampers to structures is recognized as one of effective measures decreasing seismic damage from primary structures. Recently a bingham type damper has been noticed because of its predominant characteristics such as no dependence on both velocity and temperature. In this paper, the bingham dampers with newly composed materials are examined experimentally. Preferable combination between silicon oil and some fillers are found after the dynamic test changing the frequency from one to five Herz.

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In a deck type arch bridge,very big up-lift forces for bearing supports and section forces beyond yield stresses occur in many members during a large earthquake. Therefore, an effective seismic retrofit design using damper is proposed to reduce dynamic response. For a target spandrel braced arch bridge with 214m span length, we improved an analysis model to a model with the meaning of damage process of bearing. Furthermore, three effective plans are put together to make one superior plan. In evaluation of seismic safety of each member, importance of the member and mechanism of the damage are considered.

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This paper deals with the effects of equipment for preventing bridge from falling down during ultimate ground motions. Generally, usual equipments with energy absorbing system using PC connection cables are installed at bridge with short and middle spans. In TE-type equipment focused in this paper, control steel pile is added to PC connecting cables and a wedge-plate is penetrated into the pile with energy generated by deforming it during some ultimate ground motions. In this analysis, the effects of equipment characteristics on bridge response subjected to severe earthquake are investigated.

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Unseating prevention cables have been widely used to avoid bridges from unseating. However, it has not been thoroughly investigated that whether brackets and web plates where unseating prevention cables are connected are adequately designed against the loading during earthquakes. In this study, a steel girder with unseating prevention cables were loaded in tension by the falling weight simulating the case that a girder is unseated, then unseating prevention cables become active as the girder is falling down. Test results indicated that the elongation of the unseating prevention cables and the displacement of the falling weight were related by simple equations. It was also found that the brackets and the web panels have adequate strength against the loading by falling weight.

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Functional characteristics of shock absorbing rubber is investigated by dynamic loading test and load- displacement relationship and its energy absorption characteristics are obtained in this study. By modeling its energy absorption characteristics, application to real bridge structures is analyzed by numerical calculations. And proposed shock absorbing rubber functioned well for strong earthquake impact and effectiveness to real bridges was shown in numerical results.

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Dynamic analysis was performed to evaluate the effect of expansion gap and surpporting ground conditions under the abutments on the collision force and movement between the girder and abutment. The results showed, as the expansion gap became small, the collision frequency increased, however the collision force reduced.

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This study investigated the flow and the hydrodynamic force characteristics acting on a bridge during a tsunami event using hydraulic experiments and numerical analysis. Characteristics such as wave height, flow regime, and the hydrodynamic force for rectangular and channel section bridge models were measured, and numerical analysis using the particle method was conducted. The experimental results showed that the impulsive hydrodynamic force acting on a rectangular section model during a tsunami event was larger than that observed using a channel section model. Thus the shape of bridge girder needs to be taken into account in the design load for a tsunami event.

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The wake excitation of tandem circular cylinders is very complex phenomenon, because that is affected by the interaction between the motion of circular cylinders and the flow around those, and Reynolds number effect. To clarify the mechanism of this phenomenon, the wake excitation of a circular cylinder in the wake of a prism, which was replaced instead of a windward circular cylinder to reduce the effects of Reynolds number, was investigated by free vibration tests, unsteady pressure measurements and flow visualization tests. The ensemble rms pressure, which was defined as an fluctuating pressure asynchronizing with the motion of the circular cylinder, reflects the condition of the separation flow near the circular cylinder clearly. As the results of the unsteady pressure measurements and the flow visualization tests, it was clarified that the motion of the separation flows from the windward prism plays an important role on the wake excitation of the leeward circular cylinder.

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This paper proposes a practical method for input-output vibration-based health monitoring. The method using degree of nonlinearity (DON), which overcomes the limitation of linear models, is proposed. Derived from the Hilbert transform of the frequency response function, the DON can measure how much the nonlinearity is present in the vibration response. The results in this paper show that the DON of a structure has a specific relationship with the magnitude of the excitation. When computed from the structure that is still healthy, this relationship can be used as a baseline for the health monitoring. If the structure is not healthy, the new computed DON will deviate from this baseline.

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This paper proposes experimental approaches on the repair effect of an acryl resin to damaged concrete. Mechanically different three types of the repair specimens are used. First one is the cohesion performance test specimen which has a horizontal split plane repaired by acryl resin. Its bond performance is evaluated by direct tensile test. Second one is the shear stress performance test specimens which have a diagonal split plane repaired by acryl resin. Its shear resistance is evaluated by ordinal compression test. Third one is a micro-crack damaged specimen of which cracks are repaired by infiltrated acryl resin. Its repaired effect is evaluated by using ordinal compression test.

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Adhering carbon fiber sheets onto RC piers is one of the seismic strengthening methods. When the pier has an irregular shape, however, carbon fiber sheets cannot be adhered continuously around the pier and the edge of the carbon fiber sheets have to be fixed with steel plates and anchor bolts. This fixing method has shortcomings. For example: (1) The steel plate is heavy, (2) The execution of work is dangerous because a crane must be used to lift the steel plates. Then, an alternative fixing method using CF-anchors, which consists of bundles of carbon fiber strands, was developed, and the equation of pll-out strength between the CF-anchor and the concrete was proposed.

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This paper deals with application of a Non-Destructive actually measured Inspections on the calculation of residual flexural capacity of RC-beams with corroded re-bar. Reliability of the Non-Destructive Inspections is verified by comparison with actual measured dimensional values of corroded re-bar. And, the calculated residual flexural capacity is evaluated with loading test of RC-beams. In addition, effects of the diameters and covers of re-bar on the Non-Destructive Inspections are discussed.

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Recently, it becomes very important to evaluate remaining load bearing capacity of existing deteriorated structure. However, there is a rare opportunity to assess remaining capacity of deteriorated structures. In this study, we investigated load bearing capacity of an existing RC structure that has severe delamination of cover concrete. In order to evaluate exact capacity of them, dynamic strain responses of main reinforcing bars were measured with video image of passing cars. Next, to confirm the validness of the investigation, their strain responses are simulated by three-dimensional finite element analysis. In the analyses, delamination of cover concrete and corrosion of reinforcing bar are modeled as degradation effects and stiffening effect of asphalt paving is also considered. As a result of these analyses, it is confirmed that object structure has enough remaining load bearing capacity although they have severe delamination condition of cover concrete.

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Maintenance standards with quantity of a corroded steel structure are requested strongly for practitioner to maintain the deteriorated structures rationally. Because stresses in aged structures have been increasing gradually due to corrosion, it is necessary to judge the following problems: a) Is it rational to use the same evaluation procedure as design standard in maintenance? b) If not, what is a preferable maintenance management procedure? In this paper, we investigated the current maintenance standards in various technological fields, and through the comparative study of stress estimation methods of radial gates, we propose a way of thinking for maintenance of radial gates based on reliability theory.

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In this paper, a simple and handy test method for determination of the tensile crack bridging law of PCM-concrete interface is proposed. Based on the fatigue failure mechanism of PCM-concrete interface that is governed by crack propagation as the result of interface bridging degradation, the J-integral method proposed for determining the tension softening relation of concrete under static loading is modified to determine the PCM-concrete interface tensile stress degradation relation. The derived degradation relation is compared to that of normal concrete under cyclic uniaxial tensile tests, and it can be found that the PCM-concrete interface has higher degradation rate so that more attention should be paid to the PCM-concrete interface during the design of PCM-retrofitted structures under fatigue loading.

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Fatigue tests have been carried out on three types of non load-carrying fillet welded joint subjected plate bending, such as single-side fillet welded joint, T-shaped fillet welded joint and cruciform fillet welded joint. Fatigue failure mode of each type of welded joint has been demonstrated. The test results show that fatigue crack forms flat semi-ellipse during crack propagation and propagates to about 80% of plate thickness before failure. The fatigue strength and life recorded under bending test have been assessed and compared with the previous test results. Moreover, the fatigue strength for bending is evaluated by using one-millimeter stress method.

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In Japan, most of the riveted girders in railway bridges are ageing more than 70 years. Therefore those riveted girders are suffering from much functional loss by severe deterioration due to long term environmental attacks and effective repair/strengthening methods are required.
However, it is very difficult to assess quantitatively the strength loss of a rivet joint caused by corrosion of steel plates and rivets. In this study, static loading tests on the strength of rivets were conducted on corroded rivets parts and replaced parts with high-strength bolt, which were obtained from a steel railway bridge that was removed from service and highway bridges.

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This paper summarizes an experimental study of steel pipes repaired with patch plates using underwater wet welding to evaluate strength and ductility. In this study, the thickness of a portion of steel pipes was reduced by half to simulate corrosion damage, and steel patch plates were fillet-welded to cover the reduced thickness area. For one set of specimens patch plates were welded in the open air, and for the other they were welded in the underwater wet environment to understand effects of welding environments on strength and ductility of repaired steel pipes. The specimens were tested in flexure or compression until failure. Based on the experimental results, recoveries of stiffness, strength, and ductility were evaluated, and the effectiveness of patch plates was also examined.

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It is known that underwater wet welding shows inferior properties of joints to the open air welding due to hardening by rapid cooling and weld defects from difficult welding conditions. This study was performed to understand mechanical behavior of welded connections in steel pipe repaired with cover plate by underwater wet weld. The weld shape and hardness distribution in the weld were measured, and strength tests of front fillet and side fillet welded connections were performed. Experimental results show that weld shape and hardness affect the mechanical behavior of fillet welds. Finite element analysis shows a different concentration of strain in the yield zone affects the ductility of the connection.

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The purpose of this study is to inspect the structure performance of half through arch timber highway bridge. The subjected bridge is Yusuhara Bridge constructed in Kochi prefecture on 2007. To investigate design factors, static and dynamic performance, vibration serviceability, rigidity of arch bridge and store of initial data for maintenance, the static and dynamic field tests of the subjected bridge were done with one dump truck in August 2007. The structural performance on static and dynamic behaviors were investigated in the terms such as deflection, response vibration, dynamic characteristics, dynamic increment factor and vibration serviceability. Furthermore, from the comparison of dynamic characteristics between the subjected bridge and 22 modern timber bridges measured by authors in the past in Japan, this study gives a valuable data to evaluate dynamic performance, dynamic characteristics and impact factor for modern timber highway bridges.

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Shear stiffness of glulam beams is very small compared with it's bending stiffness. While hybridization of glulam beams with inserted steel plates improves the bending stiffness, it does not so improve the shear stiffness. As a result, ratio of shear deformation to bending deformation is greater in the steel-plate-inserted glulam beams than even in glulam-only beams. Since wood members, whose toughness is very small compared with those of steel members, have tendency to drastically lose strength after fracture, it is important to investigate fracture modes and toughness of wood-steel hybrid beams like steel-plate-inserted glulam beams. The fracture modes and toughness depend on ratio of Young's modulus of wood parts to steel parts and on ratio of shear strength to bending strength. In this study we perform three-point bending tests to experimentally estimate the shear elasticity and perform asymmetric four-point-bending tests to consider shear performance and toughness of the steel-plate-inserted glulam beams for both cedar and larch.

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In the beam theory the shear stress becomes maximum value on the neutral axis, which is also adopted for hybrid structures as to steel-plate-inserted glulam beams. However, in previous its shear failure test, every specimen did not break on the neutral axis but on stress concentration zone which was observed in FEM analysis. In this study we try to experimentally and numerically investigate three types of steel-glulam hybrid beams and evaluate stress transfer mechanism between steel and glulam. In FEM analysis we search the shear stress distribution on xy cross section and compare to experiment, discuss the influence of stress transfer between different materials on failure condition.

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In applying the glulam timber to the large-sized structures, the new types of connections have been developed. In presence, there are a few joint systems using steel plates and bolts. However, those systems are not always adequately satisfied with durability. Therefore, the new joint system by prestressing was developed. In Nagano prefecture, the timber-concrete composite bridge was provided as the standard design of timber bridges, and the joint system is by prestressing. In case of concrete girder, work of prestress decrease by elastic strain, creep, and etc. However, timber-concrete composite girder is not cleared numerically. In this study, we discussed the effective prestress on timber-concrete composite girder based on time-dependent of prestress checked in existing bridge.

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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, with introduction of three sample cases of galvanizing cracks and thermal deformation, we are illustrating our analytical studies in order to figure out thermal distribution and its incidentally arising thermal stresses near galvanizing cracks. And we add examination about mechanism and the preventive measures against hot dip galvanizing cracks and thermal deformation from a provided analysis result.

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A new type of arch girder bridge, steel box girders stiffened with arch ribs, is proposed and its structural characteristics are studied. Arch ribs are concrete filled steel tubes (CFT) which have high resistance against compression and bending strength. Therefore, this bridge is expected to be rational and economical. A parametric study is carried out for different ratios of arch span length and arch rise using the performance based design method. It is found that the proposed structures have sufficient resistance against bending, compression and global buckling. This study shows the new bridge is feasible.

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Recently, various kinds of high-performance steel have been developed in order to reduce construction costs and improve structural performances. LP steel plate is applied to flange plates of steel girders with a view to reduction of process for fabrication and simplifying structures. On the other hands, it is generally known that initial imperfections of steel plates affect on the characteristics of strength and deformation of steel girders. Therefore, in this study, the fabrication error of plate thickness and the residual stress distribution subjected to metal rolling and welding are measured for the actual LP plate and box cross section in order to correct the basic imformation of initial imperfections of LP steel plates.

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In the construction of a bridge girder, a temporary structure called a saddle is often used. The saddle is composed of multiple stacked steel H-beams, each having a width and height of 150mm. The vertical load was acted the saddle due to the weight of the bride girders. The saddle member might become deformed by this load. After removing the load, the deformation might remain. This deformation is known as residual deformation. The slightly deformed saddle members are used repeatedly as well. However, there is no management standard for the saddle. In this study, the influence of residual deformation on the stability of the saddle was examined and a management standard for the saddle was proposed.

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Advantages of laser cutting over drill are the lack of physical contact and the reduction of operations in manufacture. However, loss of material at end-point of cutting line and heat-afiected zone are happened. In order to evaluation the slip resistance and fatigue strength of friction type of high strength bolted connections with laser cutting holes, slip and fatigue tests are performed. The test results indicate that the slip resistance and fatigue strength of friction type high strength bolted connection with laser cutting holes are the same as that with drilling holes.

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Recent years, rationalization of the joint structures is required from the viewpoint of reduction of the total cost of steel structures. As one of such effective solutions, adoption of super high strength bolts for friction type joints, which strength is more than 1,600MPa is considered in order to be a compact joint section with a few bolts and lines. However, the mechanical behavior of such joints, especially the behavior under compressive load, is not clear. Therefore, in this study, the mechanical behavior of the friction type joints with super/normal high strength bolts subjected to compressive load is discussed based on the FE analytical results paying attention to the maximum spacing of the bolts and contacting between joint surfaces.

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In the split tee joints, the prying force occurs due to the deformation of the tee flange plates, and the prying force reduces the strength of the joint. Therefore, it is very important for this type of joints to suppress the prying force. In order to make it possible to reduce the prying force of split tee joints easily, we propose to apply the sealant named as deformable filler plate for the split tee joints consists of soft rubber and steel rings. In this study, the mechanical behavior of split tee joints with the deformable filler plate is investigated experimentally. Particularly the influence of the sealant and shapes of the tee flange plates on strength and deformation of these joints are mainly discussed.

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It has been known that the ductility of bridge piers can be improved if they are constructed of high ductility cement, but the use of this cement is not so widespread because of cost problems. To find the most efficient use of this material for seismic strengthening of bridge piers, the authors performed a loading test using specimens with varying cover concrete thicknesses. From the experiment, it was found that the high ductility cement has the 80mm thickness, includes main reinforcement, can provide a horizontal confinement effect as much as the pier whose entire cross section is constructed of this material.

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Even if the structure is deteriorated severely due to ASR, most of the compressive cylinder specimens which drilled from the real structure, generally keeps 70% strength of the design value. Compressive cylinder tests using accelerated ASR specimens showed that even if expansive strain reached 5000μ, the reduction of strength is at most 30%, because the effect of frictional shear strength between aggregates and cement.

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