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Tadotsu, Japan

Hanji T.,Nagoya University | Tateishi K.,Nagoya University | Ono S.,Japan Construction Method and Machinery Research Institute | Danshita Y.,KAWADA Industries Inc. | Choi S.M.,Nagoya University
Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 | Year: 2013

In this study, the fatigue performance on the welded joints of the newly developed steel called Steels for Bridge High Performance Structures (simply called SBHS) was investigated. In order to clarify the fatigue crack growth characteristic of the SBHS, the crack propagation tests were performed with compact tension type specimens. Then, the fatigue strengths of out-of-plane gusset welded joints and non-load-carrying cruciform welded joints of the SBHS were investigated. Plate girder specimens, in which gusset plates were attached on their webs, were also fabricated with the SBHS and tested. The fatigue test results revealed that the fatigue performances of the welded joints of the SBHS are almost the same as those of the conventional steel. Source


Trademark
KAWADA Industries Inc. | Date: 2015-10-27

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Tsuyama T.,KAWADA Industries Inc. | Yuda M.,KAWADA Industries Inc. | Nakai K.,Ehime University
Welding in the World | Year: 2014

In the fabrication of steel structures, the method of gas-shielded arc welding is widely utilized with pure CO2 gas. However, the welding with pure CO2 gas is limited with respect to the heat input in order to maintain the fixed mechanical properties of weld metal. A new welding method for increasing weld deposit in every weld bead under keeping the fixed mechanical properties of the weld metal is proposed. An electrically heated filler wire, hereafter referred to as hot wire, was inserted to the weld pool neighboring the arc formed with a leading welding electrode. By using a hot wire without arc, the increase in heat input could be suppressed, but the amount of weld deposit could be greatly increased. In the present investigation, the effects of the welding conditions on both the microstructure and mechanical property of the weld metal are clarified and discussed from the view point of the improvement of welding conditions. Mechanical properties of the weld metal formed with F-metal active gas (MAG) could be greatly improved under high heat input. The microstructure formed with F-MAG is so fine because of the change in the chemical composition of the weld metal by the use of the hot wire. The refined microstructure in F-MAG might improve the mechanical properties of the weld metal. © 2013 International Institute of Welding. Source


Higashiyama H.,Kinki University | Yoshida K.,KAWADA Industries Inc. | Inamoto K.,Nippon Stud Welding Co. | Matsui S.,Osaka Institute of Technology | Kaido H.,KAWADA Industries Inc.
Journal of Constructional Steel Research | Year: 2014

This paper presents an evaluation of the fatigue strength of headed studs welded with improved ferrules under rotating shear force. In steel-concrete composite structures, shear connectors are essential components to transfer shear forces at the interface between steel and concrete. Particularly, headed studs in steel-concrete composite decks for highway bridges are subjected to rotating shear force when vehicle loads pass through the steel-concrete composite decks. The authors have developed welding ferrules for headed studs with higher fatigue duration than conventional headed studs. In this study, the rotating shear force was applied to the improved headed studs by using a specially developed testing machine in order to determine the fatigue strength in association with the concrete strength. The fatigue strength of the headed studs increased with the higher concrete strength and two failure modes were observed. Finally, the average S-N curves in correspondence with concrete strengths were determined for the improved headed studs. © 2013 Elsevier Ltd. Source


Tsuyama T.,KAWADA Industries Inc. | Nakai K.,Ehime University | Tsuji T.,KAWADA Industries Inc.
Welding in the World | Year: 2014

In the fabrication of steel bridge, submerged arc welding (SAW) is widely utilized. In order to increase the efficiency for the production of welds, the increase in electrode such as SAW with multiple wire electrodes is effective. However, heat input also increases with increasing the number of electrode. The new welding method based on SAW method with one electrode, F-SAW, was developed in the present investigation. An electrically heated filler wire, hereafter referred to as hot wire, was inserted into the rear part of weld pool made with leading SAW electrode. By using the hot wire without arc, increase in heat input could be suppressed but the amount of weld deposit could be greatly increased. Welding speed of F-SAW for deck plate 16-mm thick became two times compared with that with ordinary SAW. In the present study, mechanical properties of the weld metal formed with F-SAW were clarified. Mechanical properties of the weld metal formed with F-SAW could be improved, compared with those with SAW. Moreover, those with F-SAW was greatly improved by selecting the hot wire and cut wire. The microstructure formed with F-SAW was so fine. The refined microstructure in F-SAW might improve the mechanical properties of the weld metal. © 2014 International Institute of Welding. Source

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