Faculty Profiles - SHIMIZU Masaru

Evaluation of Thickness Effect on Fatigue Life Variation of Longitudinal Welded Gusset Joint

Putri, CA; Tateishi, K; Shimizu, M; Hanji, T

INTERNATIONAL JOURNAL OF STEEL STRUCTURES Vol. 24 ( 2 ) page： 246 - 255 2024.4

Publisher：International Journal of Steel Structures

Numerous studies have been conducted regarding the fatigue strength of longitudinal welded gusset joints. Most studies employed relatively small specimens. Thus, this study aims to evaluate the variation of fatigue life of longitudinal welded gusset joints by using the probabilistic fracture mechanics approach, particularly for larger specimens. Although some studies claimed that lower fatigue strength is found in the thicker main plate specimens, however only a limited number of fatigue test was conducted. A probabilistic approach was employed to conquer the shortfall. In this study, fatigue crack propagation analysis was performed on the main plate thicknesses of 12, 40, and 60 mm to evaluate the effect of main plate thickness on the fatigue life of the joints. Then, a probabilistic approach is given to investigate the variation of fatigue life of the joint. In addition, fatigue tests were carried out to investigate the crack propagation behavior on larger specimens. A significant decrease in fatigue life was observed by the increase of the main plate thickness from 12 to 40 mm, however, no further decrease thereafter. The fatigue strength of longitudinal welded gusset joints with the main plate thickness of 12 mm was appertained to category F in the JSSC design curve. Meanwhile, the fatigue strength of longitudinal welded gusset joints with the main plate thickness of 40 and 60 mm falls into category G in JSSC. This condition was also confirmed by the fatigue test results, where both specimens were classified as category G in JSSC.

DOI： 10.1007/s13296-024-00812-z

Web of Science

Scopus

Numerical simulation of fatigue crack propagation and repair with drilled hole in trough-girder bridges Reviewed

Takeshi Hanji, Kazuo Tateishi, Miki Shibata, Masaru Shimizu, Makoto Yamaguchi, Yuichiro Niwa

The 77th Annual Assembly of International Institute of Welding page： XIII-3083-2024 2024.4

タップボルト継手の疲労強度および材間相対変位の評価 Reviewed Open Access

丹羽雄一郎，舘石和雄，判治剛，清水優

鋼構造論文集 Vol. 31 ( 121 ) page： 115 - 126 2024.3

鋼床版Uリブ・デッキプレート溶接継手におけるルートの局部応力による疲労強度評価 Reviewed Open Access

清水優，判治剛，内田大介，服部雅史，吉田黎

鋼構造論文集 Vol. 31 ( 121 ) page： 72 - 87 2024.3

FATIGUE EVALUATION OF U-RIB TO DECK WELD JOINT IN ORTHOTROPIC STEEL DECK BASED ON LOCAL STRESS AT WELD ROOT Reviewed Open Access

SHIMIZU Masaru, HANJI Takeshi, UCHIDA Daisuke, HATTORI Masafumi, YOSHIDA Rei

Kou kouzou rombunshuu Vol. 31 ( 121 ) page： 72 - 87 2024.3

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Society of Steel Construction

Many fatigue tests have been conducted to reproduce a root crack in deck-to-U rib welded joints and to investigate its fatigue durability. Nevertheless, no unified fatigue strength evaluation method for the root crack has been established. In this study, total of 154 fatigue test results were reproduced in the analysis to obtain artificial notch stress at weld root, and the test results were rearranged by the notch stress. Two million cycles fatigue strength and its standard deviation based on the notch stress are discussed in this paper. Two million cycles fatigue strength tends to be higher when the mean stress in cyclic loading is in compression. By correcting the test results with the stress ratio, all test results located around a unified fatigue strength curve.

DOI： 10.11273/jssc.31.121_72

EVALUATION OF FATIGUE STRENGTH OF TAP BOLT JOINT AND RELATIVE DISPLACEMENT OF PLATES Reviewed Open Access

NIWA Yuichiro, TATEISHI Kazuo, HANJI Takeshi, SHIMIZU Masaru

Kou kouzou rombunshuu Vol. 31 ( 121 ) page： 115 - 126 2024.3

Language：Japanese Publisher：Japanese Society of Steel Construction

In this study, as a preventive maintenance method against root cracks at welded joints of cover plates, the tap bolt joint method with tap holes in both plates was proposed based on the concept of reducing the relative displacement between plates which is the cause of root crack initiation. As a fundamental study on the tap bolt joint, the fatigue strength of the joint and relative displacement of plates were evaluated by fatigue tests and FEA. It was revealed that the fatigue strengths were distributed around JSSC-E to F classes under cyclic tensile axial loads, JSSC-A class under cyclic compressive axial loads and much higher than JSSC-S class under cyclic shear loads.

DOI： 10.11273/jssc.31.121_115

疲労耐久性に優れた鋼床版垂直補剛材上端部の切欠き形状の検討 Reviewed Open Access

清水優，舘石和雄，判治剛，金子大介，末次宏基

構造工学論文集A Vol. 70A page： 458 - 469 2024.3

疲労き裂が発生した鉄塔部材の鋼管割込み継手に対する疲労損傷比の評価 Reviewed Open Access

早田直広，舘石和雄，判治剛，清水優

構造工学論文集A Vol. 70A page： 521 - 534 2024.3

鋼製橋脚角溶接部の面外曲げ作用による破壊過程と照査法の検討 Reviewed Open Access

真木有岳，川東龍則，舘石和雄，清水優，萩原直樹，稲熊唯史

構造工学論文集A Vol. 70A page： 577 - 588 2024.3

Failure processes and study on verification methods for corner weld joint of steel pier due to out-of-plane bending Reviewed Open Access

Maki Aritake, Kawahigashi Tatsunori, Tateishi Kazuo, Shimizu Masaru, Hagiwara Naoki, Inaguma Tadashi

Journal of Structural Engineering, A Vol. 70A ( 0 ) page： 577 - 588 2024.3

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

Several corner weld failures of steel piers during large earthquakes have been attributed to the rupture of corner welds with unwelded section. First, both of tensile tests and finite element analysis of the corner weld model were conducted parametrically in order to clarify the fracture mechanism of corner welds. As a result of the study, a fracture process was observed in which the cracks firstly occurred in the inner corner welds and then in the outer welds. Next the simplified verification method for the corner weld was also investigated. As a result of the investigation, it was found that the approximate bending strength can be calculated without considering the effects of stress concentration. In the future, we plan to investigate structural models through experiments and finite element analysis.

DOI： 10.11532/structcivil.70A.577

Evaluation of fatigue damage ratio for slotted tubular joints of steel tower members with fatigue cracks Reviewed Open Access

Soda Naohiro, Tateishi Kazuo, Hanji Takeshi, Shimizu Masaru

Journal of Structural Engineering, A Vol. 70A ( 0 ) page： 521 - 534 2024.3

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

Fatigue cracks were initiated at slotted tubular joints in a testing overhead transmission tower. It was estimated that the cracks were caused by vortex induced vibration (VIV). In this study, the fatigue evaluation for steel tub ular memb ers in the tower was conducted with observed wind data and a response estimation method for VIV. The fatigue damage ratios of horizontal members and web members on the north side of the tower were good agreement with the actual failure state. However, those of members in the cross arm section were low accuracy because stress ranges were similar to the cut-off limit and wind was disturbed by upwind members Moreover, it was clarified that slenderness ratio of a member with a high fatigue damage ratio was limited to a certain range.

DOI： 10.11532/structcivil.70A.521

Examination of the notch geometry effective in fatigue durability constructed to the top of vertical stiffeners in orthotropic steel deck Reviewed Open Access

Shimizu Masaru, Tateishi Kazuo, Hanji Takeshi, Kaneko Daisuke, Suetsugu Hiroki

Journal of Structural Engineering, A Vol. 70A ( 0 ) page： 458 - 469 2024.3

Authorship：Lead author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Society of Civil Engineers

In orthotropic steel deck, many fatigue crack has been found at the weld joint between deck plate and vertical stiffeners. As a counter measure for the fatigue, semi-circular notch has been adopted to reduce the stress concentration around boxing weld. However, more effective notch geometry should be considered from viewpoint of ease of construction and fatigue improvement. In this study, reduction of stress and stress intensity factor were investigated for newly developed slit-like notch and sigma-shaped notch. In addition, fatigue tests were performed for the weld joints between deck plate and vertical stiffener with sigma-shaped notch. The crack initiation life and crack propagation can be extended by constructing sigmashaped notch at the top of vertical stiffener.

DOI： 10.11532/structcivil.70A.458

PREVENTIVE MAINTENANCE MEASURES AGAINST FATIGUE CRACKS AT WELDED JOINTS OF SOLE PLATES OF STEEL BRIDGES Open Access

NIWA Yuichiro, TATEISHI Kazuo, HANJI Takeshi, SHIMIZU Masaru

Japanese Journal of JSCE Vol. 80 ( 5 ) page： n/a 2024

Language：Japanese Publisher：Japan Society of Civil Engineers

Many cases of fatigue cracks at welded joints of sole plates in steel bridges have been reported. And the causes of the cracks generation and countermeasures have been studied. However, the study has so far mainly focused on corrective maintenance, and practical preventive maintenance measures have not been established. In this study, focusing on the toe crack and root crack that generates at welded joint of sole plate, preventive maintenance measures by peening treatment and tap bolts were studied by FEA and fatigue tests. As a result, it was clarified that the peening treatment could improve the fatigue strength of the weld toe of sole plate under the conditions of compressive stress acting on the weld, and the method using tap bolts could extended the fatigue life of the weld root of sole plate.

DOI： 10.2208/jscejj.23-00234