DOI： 10.11532/structcivil.69A.953

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DOI： 10.11532/structcivil.69A.116

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DOI： 10.11532/structcivil.69A.500

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejj.22-00143

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Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/tmag.2022.3151656

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DOI： 10.2208/jscejseee.77.2_333

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DOI： 10.2208/jscejam.77.2_I_371

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DOI： 10.2208/jscejseee.77.1_59

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DOI： 10.2208/jscejam.76.2_I_89

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DOI： 10.2208/jscejseee.76.2_239

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DOI： 10.11532/structcivil.66A.868

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejseee.76.5_ii_38

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Language：Japanese   Publishing type：Research paper (scientific journal)  

The authors proposed a technique for improving the fatigue strength of the weld root by filling the resin. In this study, fatigue tests were carried out on sole plate specimens with or without filling the resin between sole and base plates. As the results of the fatigue tests, the fatigue strength of weld root was extremely improved by the complete filling the resin even for partial filling the resin. Furthermore, it was shown that fatigue life could be estimated by the fatigue strength evaluation method using deformation of the weld root.

DOI： 10.1201/9780429279119-234

Scopus

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.11532/structcivil.65A.745

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DOI： 10.11532/structcivil.65A.755

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Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/jscejam.75.2_i_571

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC STEEL CONSTRUCTION-KSSC  

DOI： 10.1007/s13296-018-0106-y

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Publishing type：Research paper (scientific journal)  

Fatigue tests and numerical analyses were carried out in order to investigate the effect of hammer peening on fatigue life of U-rib structure. The fatigue test results showed that the fatigue life of peened specimens are longer than the non-peened ones. In addition, the numerical results showed that compressive residual stresses were induced at weld toe and root by hammer peening, moreover that the accumulated plastic strains during cyclic loading can explain the experimental results in terms of fatigue life extension.

DOI： 10.2207/QJJWS.35.169S

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC STEEL CONSTRUCTION-KSSC  

In steel members strengthened by carbon-fiber reinforced polymer (CFRP) plates, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched As so far, the authors proposed a technique to reduce the thermal stress in steel members strengthened by CFRP plates, which involves bonding aluminum alloy plates with CFRP plates. In the proposed method, the thermal stress in steel member can be reduced so that there are negligible levels of stress in steel member when the cross sectional areas of CFRP and aluminum plates are designed to correspond to the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. In this study, to confirm the maintaining the thermal stress reduction in steel member by proposed method, thermal stress measurement in steel plate strengthened by CFRP and aluminum plates was carried out about 21 months. In this research, the thermal stress introduced in the steel plate strengthened by CFRP plates was also measured. Furthermore, to assume the thermal shear and normal (peel) stresses in adhesive layers, FE analysis with plane stress element was employed. As the result, it was shown the thermal stresses in steel plate with CFRP plate were able to calculate by using composite theory and measured temperature. Furthermore, in steel plate strengthened by CFRP and aluminum plates, the thermal stress introduced in steel plate was negligible-small through the all-season. It was found the thermal stresses in steel plate with CFRP plates as well as CFRP and aluminum plates were also estimated by using composite theory and measured temperature. In the steel plate strengthened by CFRP and aluminum plates, the thermal shear and normal stresses in adhesive layer glued to steel plate become smaller than that in the conventional CFRP bonded specimen. However, the shear stress in adhesive layers between CFRP and aluminum plates in proposed method was higher than the thermal stress in adhesive layers between CFRP plates in conventional method.

DOI： 10.1007/s13296-016-0055-2

Web of Science

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Language：Japanese   Publisher：公益社団法人 土木学会  

Hammer peening is one of techniques for improving fatigue strength by introducing compressive residual stress at weld toe. Hammer peening by using ICR (impact crack closure retrofit) treatment device, where flat area in front of weld toe is intentionally peened, is also able to introduce compressive residual stress at weld toe as well as near the peened area. In this study, distribution of residual stress introduced in steel plate by peening with ICR device was measured and simulated by finite element analysis considering inelastic and large deformation behavior. In the analysis, strain due to thermal expansion was computed to simulate the peening effect. The analytical showed good agreement with the test results.

DOI： 10.11532/structcivil.62A.685

CiNii Books

J-GLOBAL

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：公益社団法人 土木学会  

DOI： 10.2208/jscejam.72.i_633

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Publishing type：Research paper (international conference proceedings)  

In this paper, a new peening method in which peening is applied at back surface of the weld toe is proposed. To clarify the effect of peening from back surface of the weld toes on fatigue strength improvement, plate bending fatigue tests under stress ratios R = 0, -1 and –infinity were carried out with out-of-plane gusset specimens. Specimens were composed of steel plates either 12mm or 16mm in thickness. In this study, peening is conducted within either 30mm×80mm or 80mm×30mm (longitudinal direction × transverse direction) rectangular area at back surface of weld toe. As the results of fatigue tests, the specimens composed of12mm thick steel plates on which peening was conducted within the 80mm×30mm rectangular areas showed significant improvement of fatigue strength at stress ratios R = -1, -infinity compared to as-welded condition. The specimens composed of 12mm thick steel plates on which peening was conducted within the 30mm×80mm rectangular areas showed no significant improvement of fatigue strength. Furthermore, the specimens composed of 16mm thick steel plates with peening within the 80mm×30mm rectangular areas showed no significant improvement of fatigue strength.

Scopus

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The one-sided plate bonding method, which can be done in a short time and does not affect traffic flow, has been proposed for repairing the corrosion on the orthotropic steel deck plate. Its effectiveness and the design method of required thickness of patch plates have been studied with the loading tests and FE-analysis. It's known that the fatigue debonding phenomenon might occurs under the repetitive loading, and it is necessary to study about that phenomenon in order to develop the patch plate repair method. In this paper, the debonding of the patcth plate on the orthotropic steel deck plate has been evaluated by the fatigue wheel loading tests and FE-analysis with the real sized specimen and by the fatigue bending tests. As the results, the appropriate edge position of the patch plate on the orthotropic steel deck was proposed.

DOI： 10.11532/structcivil.62A.514

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Recently, bonding patch plate repair is focused on as an effective and rapid repair methods applied to the corrosion damaged steel structured. However, the brittle debonding of patch plate is one of the issues of this method. In this study, patch plate repair combined adhesion and stud bolt is proposed to prevent the brittle debonding of patch plate. In order to investigate the effect of proposed method, the tensile tests of steel plate repaired by steel plate with adhesion and stud bolts were carried out. As the result of the tensile tests, specimen with the proposed method prevented the brittle debonding of patch plate, and the debonding strength became higher than that in specimens with conventional bonding method.

DOI： 10.11532/structcivil.62A.639

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

On the orthotropic steel deck, thickness reduction of the deck plate sometimes occur due to rainwater from pavement crack and salt supplied by deicing agent. The one-sided plate bonding method, that can be done in a short time and do not affect traffic flow, for repairing the thickness reduction has been studied by bending tests and FE-analysis. In this paper, the effect of the one side patch plate technique is confirmed by the static and fatigue wheel loading tests and FE-analysis, using the real-sized specimen with an introduced thickness reduction which simulates corroded damage. The stress distribution due to the different size or position of the thickness reduction area were also examined. In addition, it is confirmed that the required thickness of patch plates resulting from real-sized tests and analysis have conformed with the thickness design method for the corroded plate proposed in the previous study.

DOI： 10.2208/jscejseee.72.263

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Many fatigue cracks are observed at welded toe between steel deck plate and vertical stiffener. In this study, to compare the effects of fatigue life extension of three repair methods for crack initiated at the welded toe, bending fatigue tests were carried out. The repair methods are crack removal method by disk grinder, ICR treatment and stop hole. As the results of fatigue tests, it was clear that crack removal method by disk grinder and ICR treatment could prevent crack re-initiation. On the other hand, in case of stop hole, fatigue crack was re-initiated at stop-hole edge under low stress range, if stop-hole edge was not treated by disk grinder. Furthermore, the effect of fatigue life extension by the repair methods cold be evaluated qualitatively by FE analysis.

DOI： 10.2208/jscejseee.72.192

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study investigated a crack opening-closing behavior by ICR treatment under tensile load and compressive stresses. Out-of-plane gusset specimen in which crack was propagated to boxing weld (<i>N</i>_b crack) or base plate 10mm away from the weld toe (<i>N</i>₁₀ crack) was employed. As the test results, <i>N</i>_b crack completely opened under tensile nominal stress over 40N/mm². In case of <i>N</i>₁₀ crack, a part of crack along the boxing weld opened under tensile nominal stress over 60N/mm². On the other hand, <i>N</i>_b crack completely closed under compressive nominal stress less than 120N/mm². In case of <i>N</i>₁₀ crack, crack along the boxing weld opened partially under compressive nominal stress over 60N/mm<sub>2</sup>.

DOI： 10.11532/structcivil.62A.675

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：社団法人 日本鋼構造協会  

DOI： 10.11273/jssc.22.85_39

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The impact crack closure retrofit treatment (called ICR treatment) is a technique to delay or arrest fatigue crack growth and enhance residual fatigue life of weld joints including a crack. The treatment is carried out with an air tool to peen plate near the crack and to produce plastic deformation of the steel surface in order to close crack opening. In this study, several fatigue tests on weld joints were conducted under tensile or bending loads in order to verify the life extension effect by ICR treatment. Besides, the effect of the loading types to the life extension was analytically investigated.

DOI： 10.11532/structcivil.61A.627

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

In steel members bonded with carbon-fiber reinforced polymer (CFRP) plate, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. In the previous paper, the authors proposed a technique to reduce thermal stress in steel members strengthened by CFRP plate, which involves bonding aluminum alloy plates with CFRP plates. In this research, the thermal stress introduced in the steel plate with CFRP and aluminum plates was measured over one year. As the result, it was shown the thermal stress in steel plate was neglectable small through the all-season. Additionally, a steel plate bonded carbon fiber strand sheets and aluminium plates side by side was tested. In this method, the thermal stress induced in steel plate was also reduced.

DOI： 10.11532/structcivil.61A.808

CiNii Books

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study investigated a steel patch plate bonding technique on one side for the temporary repair of through-thickness crack in orthotropic steel deck, OSD, at vertical stiffener end. Out-of-plane gusset specimen was used in this study. Fatigue tests were carried out using bending type of fatigue test machine under the stress ratio R=-infinity. Steel plate or Cabon Strand Sheets were adhered on the back surface of specimen after through-thickness crack was found. Then bending fatigue test was continued until crack propagated 50mm away from the weld toe on gusset attached surface. By bonding patch plate on the back surface of the specimen, the remaining fatigue life was extremely extended if the patch plate working. Furthermore, when the impact crack closure retrofit, ICR, treatment was applied at the crack on gusset surface with pach plate bonding on the back surface, the remaining fatigue life was also extended.

DOI： 10.11532/structcivil.61A.408

CiNii Books

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Language：Japanese   Publisher：Japanese Society of Steel Construction  

Recently, bonding patch plate is used for rehabilitation of steel structures deteriorated with corrosion or fatigue cracks. The patch plate tends to decreases the stress intensity factor at crack tip and delay the crack propagation. However, debonding of patch plates could occur around the end of patch plates and at fatigue crack edges. To evaluate debonding of patch plates bonded to the cracked steel plate, axial loading tests for butted steel joint with bonded patch plates were conducted. Furthermore, the shear and normal stresses in adhesive layer were analyzed. The debonding strength of the joint was evaluated from a view of principal stress in adhesive layer.

DOI： 10.11273/jssc.22.86_1

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Carbon fiber reinforced polymer, CFRP, plate bonding method is one of the new crack repair methods. The effect of fatigue life extension by bonding CFRP plate can be estimated by using stress intensity factor, SIF. In this study, to clarify the effect fatigue life extension of edge crack by bonding CFRP plate under axial load, tensile fatigue tests were carried out. Furthermore, to evaluate the effect of fatigue life extension by bonding CFRP plate, stress intensity factor, SIF, of a cracked steel plate with CFRP plates was calculated by finite element analysis and simple calculation procedure based on linear fracture mechanics. Finally, crack propagation analysis were carried out and analysis results compared with test results.

DOI： 10.2208/jscejam.71.I_795

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

For strengthening of steel members suffering deterioration and/or insufficiency of load carrying capacity, externally bonding patch plate have been used. Furthermore, pretensioned patch plate have also been used in several strengthening cases. Although the pretensioned patch plate can improve stress in steel member not only by live load but also dead load, the shear and normal stress tend to be introduced in adhesive layer. The stresses may cause the reduction of debonding load of patch plate. To improve the debonding load of pretensioned patch plate, applying non-pretensioned region at the end of patch plate was proposed. In this study, prestress introduced into steel plate by partially pre-tensioned patch plate was observed. In addition, the improvement of debonding load due to the non-pretentioned region is confirmed from debonding tests. The improvement effect in the debonding load is evaluated from the view of principal stress in adhesive.

DOI： 10.2208/jscejam.71.I_849

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

It is well known that the fatigue strength of weld toe can be improved by peening which introduces the compressive stress. However, when the compressive over load (OL) is subjected after peening, the compressive stress of welded toe is released and effect of improvement of fatigue strength becomes small. In the previous research, the authors carried out fatigue tests of out-of-plane gusset joint and clarified that the improved fatigue strength is reduced by subjected the compressive OL. In this paper, to evaluate the reduction of improved fatigue strength by the compressive OL, fatigue tests of T-joint were carried out. Furthermore, fatigue strengths of out-of-plane gusset joint and T-joint subjected compression OL after peening were estimated by using the elasto-plastic large deformation analysis and the modified Goodman Diagrams.

DOI： 10.11532/structcivil.61A.638

CiNii Books

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MULTI-SCIENCE PUBL CO LTD  

In steel members strengthened with carbon-fiber reinforced polymer (CFRP) plate, thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. Therefore, the thermal stress caused by temperature change has to be considered when designing the repair or strengthening of a steel member with CFRP plates. With this in mind, the authors proposed a technique to reduce thermal stress in steel members strengthened by CFRP plate on both side, which involves bonding aluminum alloy plates with CFRP plates. In this proposed method, the thermal stresses in steel member can be reduced so that there are negligible levels of stress when the cross sectional areas of CFRP and aluminum plates are designed to correspond the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. So far, a thermal bending moment was not considered in the proposed method, because the steel members strengthened by CFRP-aluminum laminated plate on top and bottom sides were assumed. However, if the proposed method is applied on one side of steel member, the thermal stress in the steel member might not be reduced completely by generated thermal bending moment. Therefore, to confirm the effectiveness of the proposed method for one-sided bonding, heat tests were conducted on a steel plate with a laminated plate bonded on one side. Additionally, to verify test results and calculate the shear and peel stresses in the adhesive layers, a numerical model that used Eigenvalue analysis was proposed and applied. The tests revealed that using the proposed method to create a two-layered laminated plate consisting of CFRP and aluminum plates could not reduce the thermal stress completely in a thin steel plate. However, it was found that the thermal stress in steel plate can be completely reduced, even in thin steel plate, when the proposed method is used to create a three-layered laminated plate consisting of one CFRP plate between two aluminum plates, which when composited has a thermal bending moment equal to zero.

Web of Science

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Language：Japanese   Publisher：Japanese Society of Steel Construction  

The authors proposed one technique for reduction of stress concentration at stop hole edges which is closing the crack surface between stop holes by using ICR treatment. To evaluate the effectiveness of proposed method, bending fatigue tests of stop hole with ICR treatment were carried out. As the results of bending fatigue tests, fatigue strength of stop hole with ICR treatment was 3 times higher than that without ICR treatment. Additionally, to estimate fatigue strength of stop hole with ICR treatment, estimated equation of stress range of stop hole with ICR treatment was proposed. Fatigue life can be accurately estimated by using the proposed equation.

DOI： 10.11273/jssc.21.53

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Language：Japanese   Publisher：Japan Concrete Institute  

For weight reduction of CFT members, concrete-filled double skin steel tubular members, CFDT, have been developed. To ensure the composite action of CFDT members, shear connectors should be installed at the interface between steel tubes and concrete. In this study, to investigate the effect of shear connector on the bending behavior of CFDT members, four-point bending tests were carried out on CFDT and CFT members with shear connectors. The locations of the shear connectors were different for each specimen. The shear connectors were found to prevent slip between steel tubes and concrete. The maximum load of CFDT members was improved by shear connectors, particularly when placed on the inner surface of the outer steel tube.

DOI： 10.3151/crt.25.45

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

As a simple repair technique for steel members suffering from corrosion attacks and fatigue damages, bonding patch plate have been used. In the patch plate bonding repair, the prevention of delamination of patch plate is one of the main concerns. Therefore, some verification is strongly required to prevent the delamination of patch plate. For the evaluation of brittle failure like debonding, the energy release rate is often used. However, the energy release rate previously proposed does not take into account the delamination mode I and II. In this study, mode I/II energy release rates by using normal and shear stresses in adhesive layer are derived for cracked steel plate repaired with patch plates on both side. By using high accuracy solution of normal and shear stresses in adhesive layer, both energy release rates almost agree with the results of FEM analysis.

DOI： 10.2208/jscejam.70.I_899

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Language：Japanese  

DOI： 10.2208/jscejam.69.I_595

J-GLOBAL

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to propose the simple calculation procedure of stress intensity factor of a cracked steel plate repaired with patch plates. In this paper, firstly, stress intensity factor, SIF, of a cracked steel plate with patch plates was calculated by finite element analysis. The effects of SIF reduction of crack repaired with patch plates were assumed as the reduction of nominal stress and the control of crack opening displacement by patch plate. Then, by applying these effects, the SIF of cracked steel plate with patch plates was estimated by a simple calculation procedure. Finally, it was confirmed that the estimated SIF agrees with that given by FE analysis.

DOI： 10.11532/structcivil.59A.798

J-GLOBAL

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Recently, corrosion damages on upper surface of orthotropic steel deck have been found during the pavement repair work in urban expressway. Thus, a simple repair method for corrosion damages is strongly required to be done during the pavement repair works. Therefore, the authors focused on the bond repair method using patch plates of steel or CFRP. However, in pavement repair, asphalt with temperature of 200&deg;C or more is paved on the upper surface of orthotopic steel deck. Accordingly, adhesive used for bond repair is also exposed to high temperature by asphalt paving. In this study, to clarify the effect of high temperature to the debonding strength of patch plate, steel plates adhesively-repaired with patch plate exposed to high temperature during curing were bending tested. As a result, debonding strength did not decreased by exposing the high temperature during curing of adhesive.

DOI： 10.11532/structcivil.59A.657

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC STEEL CONSTRUCTION-KSSC  

Concrete Filled Tubular steel (CFT) member, which represents a superb deformability due to well-known confined effect between steel tube and concrete, has been used mainly as bridge pier. As a progressive composite member, Concrete Filled Double tubular steel (CFDT), which is consist of double skin steel tubes and filled concrete between them, has been proposed. Although a lot of reports on mechanical characteristics of the CFDT member are presently published, the necessity of shear connector for the CFDT member has not been addressed. In this research, the shear connector was installed at the interface between tubes and concrete in the CFDT member. To investigate the effect of the shear connector on the bending characteristics, the four points bending test were carried out. The results show that integrating the steel tubes and concrete enhances its bearing capacity. Furthermore, the strains of outer and inner tubes were also discussed in this paper.

DOI： 10.1007/s13296-013-1005-x

Web of Science

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC STEEL CONSTRUCTION-KSSC  

ICR (Impact Crack-closure Retrofit) treatment was developed for extending fatigue life of cracked steel structures by closing the fatigue crack opening. By applying the ICR treatment to as-welded condition, compressive stress remains at weld toe. Therefore, ICR treatment can be used for the improvement of fatigue strength of welded joint at the same level of the other fatigue strength improved techniques. If a compression overload is subjected after ICR treatment, however, the residual compressive stress at weld toe will shift the tensile stress region. Accordingly, improved fatigue strength of welded joints by ICR treatment will be reduced after the compression overloaded. In order to investigate the effect of the compression overload on fatigue strength improved by ICR treatment, fatigue tests of out-of-plane gusset specimens were carried out. As the results, fatigue strength improved by ICR treatment was hardly reduced under the compression overload condition of nominal stress of -190 MPa.

DOI： 10.1007/s13296-013-1016-7

Web of Science

J-GLOBAL

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Language：Japanese   Publishing type：Research paper (scientific journal)  

In this paper, one technique for reduction of stress concentration at stop hole edges by closing the crack surface between stop holes using ICR treatment was proposed. Tensile and bending test results showed the effectiveness of reduction of stress concentration until opening the closed crack. In tensile test, closed crack opened after nominal stress of 100MPa, while closed crack did not open under nominal stress of 200MPa in bending test. Finite element analysis results also showed that the stress at crack closed by ICR treatment under tensile load was higher than that under bending moment. By closing the crack surface in both sides, the second moment of inertia is recovered about 70% of that without crack. On the other hand, the cross-section area closed by ICR treatment becomes one third of that without crack. Therefore, the nominal stress when the closed crack open under bending moment was higher than that under tensile load. Additionally, it was found that the stresses at closed crack under tensile load and bending moment were higher than that estimated stress by structural mechanics. The reason of this is that the stresses in closed crack area and in ligament areas are not sufficiently distributed. In this research, to estimate the stresses introduced at closed crack under tensile load and bending moment, simple equations considering the bias of stress distribution were also proposed. © 2013 The Society of Materials Science, Japan.

DOI： 10.2472/jsms.62.33

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

In the application of multiple Carbon Fiber-Reinforced Plastic (CFRP) plates onto a structural steel member, stepping of the CFRP plate ends is often adopted to prevent debonding. This approach requires the nonuniform extension of CFRP plate lengths. In this study, to shorten the length of CFRP plates, a nonuniform overlapping arrangement of several CFRP plate ends was proposed and the theoretical conditions of arrangement were proposed. Additionally, the design for the stepped-end arrangement of CFRP plates under a uni-axial load was shown. It was confirmed with stress analysis that the stress in the steel plate was reduced to the design value by bonding the CFRP plate with the proposed stepped ends.

DOI： 10.2208/journalofjsce.1.1_22

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Language：Japanese   Publishing type：Research paper (scientific journal)  

In this paper, one technique for reduction of stress concentration at stop hole edges by closing the crack surface between stop holes using ICR treatment was proposed. Tensile and bending test results showed the effectiveness of reduction of stress concentration until opening the closed crack. In tensile test, closed crack opened after nominal stress of 100MPa, while closed crack did not open under nominal stress of 200MPa in bending test. Finite element analysis results also showed that the stress at crack closed by ICR treatment under tensile load was higher than that under bending moment. By closing the crack surface in both sides, the second moment of inertia is recovered about 70% of that without crack. On the other hand, the cross-section area closed by ICR treatment becomes one third of that without crack. Therefore, the nominal stress when the closed crack open under bending moment was higher than that under tensile load. Additionally, it was found that the stresses at closed crack under tensile load and bending moment were higher than that estimated stress by structural mechanics. The reason of this is that the stresses in closed crack area and in ligament areas are not sufficiently distributed. In this research, to estimate the stresses introduced at closed crack under tensile load and bending moment, simple equations considering the bias of stress distribution were also proposed. © 2013 The Society of Materials Science, Japan.

DOI： 10.2472/jsms.62.33

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Institute for FRP in Construction (IIFC)  

Recently, repair or strengthening of steel members by externally bonding Carbon Fiber Reinforced Polymer, CFRP, plate have been reported. While bonding CFRP plate can easily achieves increase in stiffness and strength, the debonding of CFRP plate from its ends is concerned. In Japan, the CFRP plates are also employed for enhancement of steel members with deterioration, fatigue cracks or low load-carrying capacity. Nevertheless, the verification method for debonding of CFRP plate has not been established. In this research, to encourage the development of verification method for debonding of CFRP plate, the differential equations of steel member with CFRP plate under typical load conditions, which are concentrated load and uniformly-distributed load, were derived and solved. As a result, the estimation equations of shear and normal stresses in adhesive at CFRP plate ends under typical load conditions were given. The shear and normal stresses at CFRP plate ends were provided as the functions of cross-sectional forces acting in the CFRP plate ends, regardless their distributions. Furthermore, the loading test on the cantilevered steel plate with bonded CFRP plate was conducted. Debonding strength from the test results was approximately evaluated with principal stress in the adhesive, which is calculated from the estimated shear and normal stresses proposed in this paper.

Scopus

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Recently, corrosion on top surface of orthotropic steel deck plate has been often found during the bridge pavement repair work in urban expressway. Repair methods for these damages are required to be finished quickly, for example within one or two hours, during the pavement repair work. The authors focused on the steel patch plates bonding repair method with adhesive from the top surface on one side. In this study, cantilever bending tests and FE analysis were carried out and stress behavior of repaired part was discussed. Besides, simple equations for designing of thickness and length of patch plate were proposed.

DOI： 10.11532/structcivil.59A.647

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Language：Japanese  

DOI： 10.2208/jscejam.69.I_701

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Language：Japanese   Publisher：Japan Concrete Institute  

Recently, to minimize thermal cracks that occur due to excessive temperature differences, several slits have been provided as a crack-prevention measure in the concrete guard walls of bridges. However, this practice may affect the amount of stress in steel girders due to insufficient stiffness of these bridges. This paper presents an investigation of the effect of crack-prevention slits on steel girders through the use of FEM analysis. A RC deck bridge with 4 steel plate girders was used as the model bridge. Our analysis revealed that the stress in the lower flange of exterior girders exceeds that of bridges that have no concrete guard wall when the slits are provided at a long distance from each other.

DOI： 10.3151/crt.24.113

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DOI： 10.2208/jscejseee.69.89

J-GLOBAL

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DOI： 10.2208/jscejseee.69.26

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Committee of the SCMT conferences  

Some cases of rupture of reinforcing bars in concrete structures have been reported because of deterioration of concrete due to ASR (alkali silica reaction). In previous studies, the rupture can be detected with one of non-destructive testing methods called magnetic flux density method (hereinafter, magnetic method). The process of the method is, firstly, to magnetize steel bars to test with a permanent magnet, and secondly, to measure magnetic flux density over the cover concrete. However, to detect the corner rupture of a steel bar, this method needs a premise: two surfaces should be accessible. Concrete structures often include superstructures near the corner in which reinforcing bars are arranged. In such cases, it is necessary to conduct the test from one surface. In this study, the magnetic method to single surface was examined with a view point of suitable indices to judge the corner rupture of multiple and continuously arranged steel bars by experiments and FE analyses. It was also focused to simplify the magnetization process in the magnetic method applied to single surface. As a result, a proper and simple method for detecting the corner rupture of multiple steel bars was proposed.

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DOI： 10.11273/jssc.19.76_97

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DOI： 10.2208/jscejam.68.I_715

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DOI： 10.2208/jscejam.68.I_703

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASCE-AMER SOC CIVIL ENGINEERS  

This study reported fatigue test results of 300-mm-wide specimens with three details: 80% partial joint penetration (80%PJP), weld melt-through (WMT), and both. The specimens were cut out from full-scale orthotropic deck specimens of 16-mm-thick deck plate. In the fatigue test, the deck plate was subjected to cyclic bending loading and the rib was free from loading. The fatigue fracture surfaces showed that the presence of WMT may affect the initiation of fatigue cracks. A propensity to root cracking rather than toe cracking was observed. Plotting fatigue test results in an S-N diagram showed that the specimens with WMT seemed to have slightly lower fatigue strengths than the 80%PJP specimens, but the difference is more likely to be within a usual scatter of test data, which means that both details have comparable fatigue strength. The present test results satisfied the S-N curves of JSSC-E (80 MPa at 2x10(6) cycles) or AASHTO-C (89 MPa at 2x10(6) cycles). DOI: 10.1061/(ASCE)BE.1943-5592.0000181. (C) 2011 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)BE.1943-5592.0000181

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

In this paper, fatigue tests have been conducted on specimens, which are flat plate with a notch, studwelded plate, T-shaped fillet welded joint and cruciform fillet welded joint, in such a way that fatigue cracks could be initiated and propagated in bending load. Under bending load, surface crack has formed flat semi-ellipse and propagated to about 80% of plate thickness before failure. Besides, the fatigue crack propagation life of cracked welded joint specimen has been predicted using fracture mechanics method. In particular, a correction factor equation has been developed for covering linearly varying stress distribution along crack propagation path under bending load. This equation has been applied to calculating stress intensity factor (SIF) in relation to fatigue life prediction. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.ijfatigue.2010.12.002

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DOI： 10.2208/jscejam.67.I_767

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DOI： 10.11532/structcivil.57A.852

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DOI： 10.2208/jscejseee.67.351

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DOI： 10.2208/jscejseee.67.336

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DOI： 10.2208/jscejam.67.I_777

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Language：English   Publishing type：Research paper (scientific journal)  

Various types of fatigue cracks have been found in steel bridges. To maintain steel bridges, repair and retrofit methods of such fatigue cracks have been developed. The authors developed a technique which generates plastic deformation of steel surface near the crack in order to close crack opening by an impact air tool. This method is called Impact Crack Closure Retrofit treatment (ICR treatment). Plate bending fatigue tests of out-of-plane gusset specimens were carried out. Fatigue cracks at turn-around welds and those which have propagated 10 and 20 mm were ICR-treated. Fatigue test results showed significant improvement in the fatigue life of specimens due to ICR treatment.

DOI： 10.2208/jsceseee.28.21s

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DOI： 10.11532/structcivil.57A.1034

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DOI： 10.11273/jssc.18.70_39

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Language：Japanese   Publisher：JAPAN WELDING SOCIETY  

DOI： 10.2207/jjws.79.328

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Other Link： https://jlc.jst.go.jp/DN/JALC/00353063790?from=CiNii

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

&nbsp;&nbsp;For the CFRP bonded to butted steel plates, higher stiffness of CFRP plates is required to reduce the shear stress in adhesive at butt end. However, as the stiffness of CFRP plates becomes high, shear stress in adhesive at the ends of CFRP plates becomes also high. Therefore, it can be presumed that the shear stresses in adhesive at butt end as well as at CFRP plate ends become small by bonding CFRP plates with stepped ends. In this study, CFRP step-bonded to butted steel plates is theoretically analysed. Then, the conditions to minimize the shear stress in adhesive for CFRP step-bonded to butted steel plates are given.

DOI： 10.2208/jsceja.66.717

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DOI： 10.11532/structcivil.56A.77

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DOI： 10.11273/jssc.17.65_43

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DOI： 10.2208/jsceja.66.368

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DOI： 10.2208/jsceja.66.368

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DOI： 10.2208/jsceja.66.264

J-GLOBAL

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DOI： 10.2208/jsceja.66.264

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Steel and concrete composite deck, which is arranged channel shape steel members in the transverse direction on the top surface of the bottom steel plate, has been investigated by the authors. By the arrangement of channel shape steel members welded to the bottom steel plate, the steel and concrete composite deck with cellars in the concrete becomes to be more lightweight than typical types of steel and concrete composite decks. For highway bridge decks, it is very important to verify the fatigue strength of the welded joint In this paper, fatigue tests of the welded joint between the channel shape steel and the bottom steel plate were carried out under the tensile fatigue stress. ©2009 The Society of Materials Sdence,.

DOI： 10.2472/jsms.58.937

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Language：Japanese   Publishing type：Research paper (scientific journal)  

Steel and concrete composite deck, which is arranged channel shape steel members in the transverse direction on the top surface of the bottom steel plate, has been investigated by the authors. By the arrangement of channel shape steel members welded to the bottom steel plate, the steel and concrete composite deck with cellars in the concrete becomes to be more lightweight than typical types of steel and concrete composite decks. For highway bridge decks, it is very important to verify the fatigue strength of the welded joint In this paper, fatigue tests of the welded joint between the channel shape steel and the bottom steel plate were carried out under the tensile fatigue stress. ©2009 The Society of Materials Sdence,.

DOI： 10.2472/jsms.58.937

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Language：Japanese   Publisher：The Adhesion Society of Japan  

DOI： 10.11618/adhesion.45.139

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Other Link： https://jlc.jst.go.jp/DN/JALC/00329520838?from=CiNii

Language：Japanese   Publisher：Japanese Society of Steel Construction  

Fatigue evaluation of trough rib to deck weld joint failed in weld throat is presented. S-N curve of the joint is determined in term of stress range in weld throat by carrying out plate bending fatigue tests and collecting previous test data. Two approaches are proposed for calculating stress range in weld throat in actual bridge with orthotropic steel deck based on one or two points of measured stress. Both methods give approximate fatigue lives, suggesting one point of stress measurement is also possible in practice. By stress measurement at an actual bridge with orthotropic steel deck, stress range in summer tends to be higher and thus more damaging than in winter.

DOI： 10.11273/jssc.16.64_11

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DOI： 10.2208/jsceja.65.961

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Since stud shear connectors are used for the connection of an aluminum deck to a steel girder, composite effects are produced between both. In this study, statically loading tests of composite girders consisting of an aluminum deck and a steel girder clarifies their yield and maximum loads as well as their behavior of collapse. Applicability of the incomplete composite theory to the composite effects of an aluminum deck with a steel girder is verified by the elastic behavior of the test girders.

DOI： 10.11532/structcivil.55A.1172

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Language：English   Publisher：Japan Society of Civil Engineers  

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.

DOI： 10.11532/structcivil.55A.871

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Language：English   Publisher：Japan Society of Civil Engineers  

The load when CFRP strips peel off from steel plates, namely debonding load is known to become higher by stepping the ends of the CFRP strips. However, the conditions to make the debonding load highest has not been clarified yet. In this paper, in the case two CFRP strips are bonded, that is, one step provided at their ends, the stiffness ratio of the CFRP strips and the length of the step to maximize the debonding load are given by theoretical analysis.

DOI： 10.2208/jsceja.65.362

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

The load when CFRP strips peel off from steel plates, namely debonding load is known to become higher by stepping the ends of the CFRP strips. However, the conditions to make the debonding load highest has not been clarified yet. In this paper, in the case two CFRP strips are bonded, that is, one step provided at their ends, the stiffness ratio of the CFRP strips and the length of the step to maximize the debonding load are given by theoretical analysis.

DOI： 10.2208/jsceja.65.362

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC STEEL CONSTRUCTION-KSSC  

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 of each 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 examined and compared with the previous results obtained by tension test. The fatigue strength of the fillet welded joint under bending is higher than that of the welded joint under tension.

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DOI： 10.2208/journalam.11.903

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DOI： 10.11532/structcivil.54A.842

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DOI： 10.2208/jsceja.64.789

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DOI： 10.2208/jsceja.64.789

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DOI： 10.2208/jsceja.63.655

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10641073

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DOI： 10.2208/journalam.10.963

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Other Link： http://dl.ndl.go.jp/info:ndljp/pid/10641072

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DOI： 10.11532/structcivil.53A.1313

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DOI： 10.2208/jsceja.63.655

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNO-PRESS  

In steel bridges fatigue cracks are sometimes repaired by placing drilled holes at the crack tips. From the meaning that the drilled holes stop the propagation of cracks, they are called stop-holes. Since stop-holes are regarded as an emergency measure to delay crack propagation, usually some substantial repair follows. However, if the stress at the stop-holes is below their fatigue limit, fatigue cracks would not be expected to occur. The purpose of this study is to present the conditions under which stop-holes prevent the re-initiation of fatigue cracks. The fatigue limit of stop-holes and the equations necessary to estimate the maximum stress on the circumference of the stop-holes are provided.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Soc Mater Sci, Japan  

Recently there have been many reports on the stress measurement of highway bridges. However, a generalized method is not still provided on how to introduce the results of stress measurement into the fatigue reliability assessment. In this paper, two new parameters, called 'fatigue resistance c' and 'fatigue-damage-accumulation q', are proposed to make it easy to introduce the results of stress measurement of a monitored bridge into the fatigue reliability assessment of highway bridges. Using a fatigue test database, the probability distribution of c is determined for various structural details. It is shown that for fatigue failure, the assumption of q = c is equivalent to the Miner's linear damage rule. The characteristics of the fatigue-damage-accumulation q of highway bridges are discussed. The application of the advanced first-order second-moment method to the state function of g = c - q gives the fatigue reliability assessment of highway bridges. It is expressed in terms of the design equivalent stress range and the allowable fatigue stress range with partial safety factors. The relation between the safety index and the lapse of time from opening to traffic is formulated. The safety index is shown to decrease with the time in logarithm scale.

DOI： 10.2472/jsms.47.1233

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Language：English   Publisher：CRC PRESS-TAYLOR & FRANCIS GROUP  

© 2016 Taylor &amp; Francis Group, London. In Japan, many fatigue cracks from weld root between orthotropic steel deck and trough rib have been found. So far, there is no effective method to improve fatigue strength preventing weld root crack between orthotropic steel deck and trough rib as an after-construction procedure. One reason for this is because the location of fatigue crack initiation tends to be inside the closed trough rib. In this study, the authors propose one technic to improve the fatigue strength of the weld root between orthotropic steel decks and trough ribs from outside the closed rib. The technique is conducted with peening in front of the weld toe outside the trough rib. The residual compressive stress will be introduced at the weld root at inside the trough rib by the peening from outside the closed rib. The fatigue strength improvement of weld root between orthotropic steel decks and trough ribs by the peening from outside the closed rib was revealed by the bending fatigue tests.

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Language：Japanese   Publisher：JAPAN WELDING SOCIETY  

本研究では、材料の繰返し弾塑性挙動を反映した疲労寿命の予測技術を採用することにより、Uリブへのピーニング処理技術および疲労き裂発生寿命にに関する数値解析を実施するとともに、供試体を対象とした実験結果との比較を通じてその精度を検証した。

DOI： 10.14920/jwstaikai.2016f.0_358

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Language：Japanese   Publisher：一般社団法人 溶接学会  

本研究では，ピーニング処理技術に関連するメカニズムの明確化とそれを基にした最適化手法の確立を目的として，メカニカルな打撃を採用するピーニング処理に関する基礎的な実験を行うとともに，同条件を模擬した弾塑性FEシミュレーションを実施し計測結果と比較することにより，繰返し圧縮に伴う形状変化や実測が困難な局所的な残留応力分布，さらに材料特性の変化などに関して考察を行う．

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Language：Japanese   Publisher：Japan Society of Civil Engineers  

Shear deformation of CFRP affects how the force transfers from a steel plate to a CFRP plate in a CFRP bonded steel plate under an axial force. A widely accepted shear lag theory to model a CFRP bonded steel plate does not usually consider the effect of shear deformation in the CFRP plate. This study proposes a way to account for the effect of shear deformation in the CFRP plate on the force transfer between steel and CFRP by increasing the thickness of adhesive layer in the conventional shear lag theory.

DOI： 10.11532/structcivil.61A.798

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Other Link： http://hdl.handle.net/10112/9481

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Patent/Registration no：4780594 

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Announcement no：2009-119607 

Patent/Registration no：5041976 

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Application no：2003-28103 

Announcement no：2004-003290 

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Application no：2004-20534 

Announcement no：2005-213825 

Patent/Registration no：4418247 

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