Hiroshi Tamura

• Yokohama National University

On the surface of the steel material (base material) undergoing repeated plastic deformation, a group of surface cracks in which multiple cracks are lined up in stripe patterns is often seen. This group of surface cracks is considered to be the source of ultra-low cycle fatigue cracks starting from the surface of steel material and has a great infl...

Bridge maintenance and repair have gained significant attention as their service life continues to extend. Numerous retrofit projects have been implemented to address the corrosion issues at steel plate girders’ ends. This study focuses on evaluating the durability of the retrofitted part of the steel girder end by assessing its ability to sustain...

Abrasive blast cleaning is often done for steel structures before applying various protective coatings, which produces rough surfaces with changes in fatigue properties. This problem has been addressed in the low- and high-cycle fatigue regimes; however, the effect of surface roughness in combination with different loading parameters on the ultra-l...

This paper investigates the effects of a wide range of loading frequencies ranging from 0.005 to 5 Hz and blasting induced surface roughness ranging from 20 to 100 μm on the ultra‐low cycle fatigue (ULCF) life of structural steel. The combined effect of these parameters on ULCF life has not been investigated so far. To this aim, comprehensive ULCF...

Bridges are valuable assets to a society to overcome barriers of connection. The dependence on the bridge increases the demand for safety and reliability of the structure. However, the operational lifetime of bridges will be affected by the integration of bridge elements and their resistance to deterioration and damage. In this paper, the identific...

This paper concerns the change in surface topography of structural steel subjected to cyclic plastic deformation considering variable surface conditions and steel types. Notched steel specimens are configured for conducting the experiment under large amplitude cyclic strain. Furthermore, a surface curvature method is proposed for the evaluation of...

This paper analyses the change in geometry of steel surface subjected to cyclic loading under the influence of various surface treatments and steel grades by focusing on spatial periodicity appearance. The process of wrinkle formation is emphasized in this research to show its relevance with crack occurrence. Mountains-Map software is used to quali...

Conducting a buckling experiment with the use of steel may provide high educational benefits in the experimental class of civil engineering course because it enables detailed observation and measurement, covering elasto-plastic buckling and offering extraordinary experience. This paper proposes a flexural buckling experiment with steel which posses...

This article presents corrosion profile estimation as a method to determine the extent of corrosion in steel members having corroded exterior, with or without protective cover, when the only side accessible to the eddy current probe is highly uneven. A high frequency eddy current method is proposed to estimate the corrosion profile of a steel plate...

This study evaluates the effect of reduction in plate thickness for a steel plate existing in concrete on guided ultrasonic SH (g-SH) waves. It has been found that the time of flight (TOF) increases if the plate thickness is reduced. The parameter investigated in this study is a delay time obtained from a TOF comparison between a healthy and a dama...

The authors have proposed a corrosion damage evaluation method for corroded steel members to estimate rust layer and residual thickness. In this method, detected voltage signal obtained by a low frequency eddy current of 500 Hz or less was used as an index. In this research, in order to further advance the method and to simplify the measurement sys...

In this research, a method which is able to analyze corrosion damage condition such as local thickness reduction or formation of rust layer of steel members of steel members at same time has been investigated. Considering eddy current testing which uses especially low frequency eddy current such as 1~1000Hz, corrosion damage condition analysis meth...

Application of maintenance to ensure the safety, extend the service life and reduce the life-cycle cost of civil structures is important. In this paper, a new inspection method is proposed using a robot which can effectively approach target sections of structures, such as areas that are either too narrow or too dangerous to approach and perform bot...

This study aims to investigate the effects of very high strain rate on low-cycle fatigue behavior of structural steel under large plastic strain with strain rate order of 1.0 s⁻¹ as expected during earthquakes. Low-cycle fatigue tests were conducted using compact-tension specimens at various strain rate levels. Fatigue life based on crack size indi...

Brittle fractures could occur from shallow surface cracks on welded parts of steel structures during earthquakes. Since the occurrence of that fracture is significantly influenced by the shape of the welded parts, the existing methods cannot predict the fractures. This study focused on a modified Weibull stress which considers the processes of nucl...

During the Kobe earthquake, unexpected brittle fracture was occurred in a corner of steel bridge bent. In this study, based on the temperature rise which was obtained from elastic-plastic FEM considering heat transfer and the transition temperature shift of critical CTOD curve due to the strain rate, dynamic loading effect on the fracture origin du...

This study investigated on the cause of brittle fracture during earthquakes from the viewpoint of structural peculiarities focusing on the stress triaxiality. The target structure is the actually fractured steel rigid bent of a highway bridge. From the investigations using nonlinear finite element analysis, it was confirmed that high stress triaxia...

This study analytically investigated on the cause of brittle fracture during the large earthquakes based on the stress triaxiality. The target structure is a steel bridge bent which was fractured during the South Hyogo prefecture Earthquake. In this bent, fracture was started from the weld bead toe exists in corner of the bent. Therefore the effect...

Stress triaxiality is proposed as one of the key parameters to discuss the cause of brittle fracture during earthquakes in steel structures. This study analytically investigated the features of stress triaxiality in steel bridge bent subjected to earthquakes. The target structure is a steel bridge bent actually fractured during the South Hyogo pref...