This paper focuses on the slip behavior of the high strength bolted friction type joint with thick filler plate and extreme thick connected plates. The filler plate is used to adjust the different thicknesses of the connected plates. It is known that the slip strength of the joint with thick filler plate is smaller than that of the joint without filler plates. To prevent to decrease of slip strength of the joint, the thickness of the filler plate is limited by Japanese Specification for Highway Bridges. By the way, the recent simplified structure of bridges makes the members large, including the filler plate of the joint, the thicknesses of the plates tend to be large. However, the investigations of the applicable range of the thickness of the filler plate focused on the extreme thick plates are not enough.
 In this paper, FEM analysis has been carried out to evaluate slip behavior of the joint. It is cleared that the smallness of the slip strength is related to the thickness change ratio, which is obtained as the ratio of the thickness of the filler plate to that of the thicker connected plate, rather than the thickness of the filler plate. And, especially in case the thickness of the filler plate is thick, unevenness of the friction stress around the bolt holes on the contact surface is one of the causes which make the slip strength small.

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 This paper provides a new hammer peening technology which makes it possible to increase the fatigue strength of welding joints more certainly than before. This hammer peening procedure of applying plastic deformation only to the base material near weld toe enables compressive residual stress to be introduced into the weld toe. In this study, a method which calculate improvement volume of the fatigue strength from required plastic deformation volume after new hammer peening treatment is proposed, based on defining the interrelationships among the compressive residual stress at weld toe, the plastic deformation after peening treatment and the fatigue strength on the fatigue test results of welding joint specimens, and FE-Analysis results. Furthermore, we have performed the bending fatigue test of steel girder with welding joints to verify the validity of the fatigue test results of welding joint specimens.

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 A versatile interaction equation expressed in terms of tri-axial force and tri-axial moment components acting at the top of thin-walled circular steel columns is derived to specify their ultimate state under the coupling of the three components of seismic excitations. This interaction equation is intended to be applied not only to the columns of normal T-shaped bridge piers but also to those of the inverted L-shaped piers and the piers of curved-girder bridges where the seismic torsional moment cannot be ignored. The interaction equation is empirically derived by the so-called pushover analysis. The validity and accuracy of the derived interaction equation is confirmed by conducting nonlinear dynamic response analysis on a 2-simple span elevated girder bridge model supported by one inverted L-shaped pier.

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 Manuals about the refuge support at the time of the natural disaster outbreak for people vulnerable to disaster such as children and elderly person have been maintained in many local governments. However, an effect of the past reporting type disaster prevention has a limit, and it is necessary to think about the measures as a public infrastructure. In this study, a damage reduction method from the natural disaster around houses, which are a place of the everyday life, is discussed. A masonry wall with the fence is considered to be a disaster prevention structure in order to develop the system which can be used not only at the time of a disaster but also at the time of daily life. The stability of the disaster prevention structure against the debris flow was investigated.
 Experiments on the strength of the disaster prevention structure against debris flow were conducted as simulating the force by debris flow by the actuator. It is examined whether the masonry wall with the fence is applicable as a disaster prevention structure by considering the strength of the wall, and possible cases in which the masonry wall with the fence can be expected as the disaster prevention structure are presented.

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 Design of a high strength bolted friction type joint on which a tensile load applies verifies slip and yield strength of the joint. The yield strength contains yield strength of net cross section of the connected plates and a frictional resistance which transferred through connected surface on the through outside of outermost bolt. The frictional resistance defined in Japanese Specifications for Highway Bridges and Recommendation for Design of Connections in Steel Structures released by Architectural Institute of Japan are different from each other.
 This paper compares the yield strengths and the yield conditions which are specified by the specifications and clarify the difference of them. And in order to clarify the yield behavior of high strength bolted friction type joint, FEM analysis for the joint is carried out focusing on a high strength bolted friction type joint which composes thick plates and many bolts. The analysis provides yield strengths based on some definitions of yielding and indicate frictional resistance transferred on the connected surface. Also, this paper discusses the yield progress of connected plates.

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 The elastic natural period and the equivalent natural period of railway structures are important indicators in the maintenance and the seismic diagnosis respectively. This paper aims to propose a method for evaluating the equivalent natural period of railway viaducts on the basis of the elastic natural period identified by microtremor measurement. The method for identifying the natural vibration modes with limited measurement points is proposed, in which the characteristics of the vibration mode shapes of viaduct groups are effectively utilized. The method enables to identify the elastic natural period of rigid frame viaducts within a error of 5% approximately. In addition, the ratio of the elastic natural period to the equivalent natural period of rigid frame viaducts is shown to be more or less constant depending on structural type of viaducts. A conversion method based on the ratio can estimate the equivalent natural period within a error of 10% approximately, applied for rigid frame viaducts. However, when the method is applied to piers, errors increase due to the effect of the coupling with the adjacent structures and the ground condition variation.

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 At present, the train operation control during earthquakes is implemented based on the earthquake motions observed on the ground surface along the railway line. To operate the trains during earthquakes adequately, the consideration of the structural seismic responses as well as earthquake ground motions is necessary. In this study, we estimated S-wave velocity structures and structural vibration characteristics using microtremore data along the model railway. And we evaluated earthquake motions not only on the ground surface but also on the structures along the railway line, using the seismic data observed at a reference site. As a result, the earthquake motions estimated are good correlations with those observed. Furthermore, we evaluated the amplification factors of the subsurface structures and the railway structures, using the earthquake motions estimated on the ground surface and the structures. These information can be applied to the judgment of train operation control. And also, it shows the week points of railway structures in which the seismic retrofit are needed before earthquakes and safety inspections are required right after earthquakes.

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 A perfobond strip is widely used as the validated shear connector in the various steel-concrete hybrid structures and in general the penetrating rebar is arranged in the perforation to suppress the brittle fracture of the perfobond strip due to the shear failure of the concrete at the perforation. However, the effect of the penetrating rebar on the shear resistance, and the effect of the perforation diameter, the penetrating rebar diameter and the thickness of the steel plate on the behavior of the penetrating rebar are not always clarified until now. In this research, in order to investigate the effect of the penetrating rebar on the shear resistance of the perfobond strip, simple push-out tests are conducted paying attention to the relation between the perforation diameter and the penetrating rebar diameter, and the variation of the steel plate thickness. Furthermore, to obtain the shear contribution of the penetrating rebar to the shear resistance of the perfobond strip, the nonlinear numerical analysis is conducted. As a result, the design formula is constructed for evaluating the shear resistance of the perfobond strip with the penetrating rebar.

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 The propagation of a compression wave generated by a high-speed train entering into a tunnel and the reduction effect of a micro-pressure wave by a portal hood at a tunnel exit have been studied with field measurements, model experiments, and numerical simulations. First, we conduct field measurement the propagation of a compression wave in a tunnel. Also we numerically simulate the propagation by solving the 1D compressible Navier-Stokes equations with an unsteady turbulence effect. The result shows that the pressure gradient of the compression wave increases as it propagates in a long tunnel for the train speed exceeding 500km/h, and thus the micro-pressure wave, whose strength is proportional to the pressure gradient of the compression wave, should be reduced. In this study, we focus on a portal hood with a porous wall as a countermeasure against the micro-pressure wave and study its effect with an experiment using a 1/34-scale model. The experimental result shows that the micro-pressure wave can be reduced by the porous hood placed at the tunnel exit, and that its reduction effect increases for a longer porous hood. Both the numerical and the experimental results agree well with the field measurement data.

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 The improvement effect on fatigue strength by introducing compressive residual stress under the variable amplitude loading has been investigated. Peening treatment and an additional welding with low temperature transformation welding material were used as the improvement methods. In addition, the change in residual stress distribution near the surface during fatigue life under variable amplitude loading was measured by the incremental hole drilling method. The results showed that a part of compressive residual stress introduced by peening treatment was released by the maximum load in the variable amplitude loading. Since the improvement effect under variable amplitude loading reduced compared with that under constant amplitude loading due to the relaxation of compressive residual stress, the damage accumulation based on the modified Miner's rule was about 0.2. The fatigue life of welded joints improved by introducing compressive residual stress can be estimated conservatively based on the results of fatigue test with constant maximum stress, which is same as the maximum stress in the variable amplitude stress.

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 It is well known that seismic response of a viaduct with batter piles tends to show the out-of-phase rocking motion unlike the case of that with normal piles. In this research, we studied out-of-phase rocking motion in consideration of dynamic soil-pile interaction and effect of reduction of inertia force triggered by out-of-phase rocking motion. We analyzed the kinematic interaction of a viaduct with batter piles with a numerical method. Next, we focused on the effective motion of batter piles and considered the effect of reduction of inertia force. The analytical results showed that the appropriate simple model which considered rotation component of effective motion could express the seismic response of the viaduct with batter piles. Finally, we proposed the static method for a seismic response analysis of the viaduct with batter piles, and confirmed the applicability of the proposed method.

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 In this paper, newly developed hybrid structural footing, in which steel grid girders are embedded, is explained in order to replace existing piers for widening double-deck superstructures. The behavior and mechanism of the hybrid structural footing under the static longitudinal and transverse loading tests are described in details. It is confirmed in the static loading tests that the longitudinal load bearing capacity of the hybrid structural footing is around three and a half times and the transverse load bearing capacity is twice of the level II earthquake load. Authors also carried out three dimensional nonlinear FEM analyses and obtained the relationship between loads and displacements, distribution of concrete cracking and stress on the steel grid girders. It is found that the analyses could simulate results of the experiments qualitatively.

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 A test specimen in the push-out test of the headed stud is generally supported by a floor and that support condition causes a lateral force acting the test specimen. This lateral force effects on the behavior of headed stud shear connectors during the test. A value of this force is not derived because the position of vertical reacting force under the floor support condition is uncertain. To solve this problem, a new push-out test of headed stud shear connectors with a simple support and a lateral restraint is proposed. This new push-out test is conducted under several conditions of support and lateral restraint, such as the location of simple support, with or without lateral restraint, and the bearing behavior of the test specimen in this push-out test is clarified. The test results show that the condition of support and lateral restraint change the boundary condition and the failure mode of test specimen.

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