Katayama Stratech Corporation

Ōsaka, Japan

Katayama Stratech Corporation

Ōsaka, Japan

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Tomoya K.,Nippon Steel & Sumitomo Metal Corporation | Tomoya K.,Osaka University | Yasuo I.,Nippon Steel & Sumitomo Metal Corporation | KOuji F.,Nippon Steel & Sumitomo Metal Corporation | And 9 more authors.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2011

Recently, ultra high strength steel plate such as 1000N (950N/mm 2 Class) class strength is focused as material of various type of steel structure. 1000N class steel has already applied in hydropower plant in order to enjoy its effect on weight and cost reduction. However, in building construction field, high strength steel remains unfamiliar material. There are only a few example of application of 780N/mm2 class strength steel in building field. Authors have already developed 1000N class steel plate and welding consumables for building. However, from viewpoint of actual application, structural performance under massive earthquake must be evaluated. Local area of column-to-beam connection seems be subject to large amount of strain when seismic event. So, in this report, low cycle fatigue properties of 1000N class steel and its weld was evaluated and structural experiments were conducted. As a result, it is revealed that Low fatigue property of 1000N class steel is equivalent to that of 780N class and can maintain the loading capacity under 26∼51 times of strain amplitude at cδp. Furthermore, it is also shown that structural performance can be estimated by test results of small specimen with strain calculation by FE analysis and finishing of edge of beam is effective for extension of lifetime through decrease of strain.


Tomoya K.,Nippon Steel & Sumitomo Metal Corporation | Yasuo I.,Nippon Steel & Sumitomo Metal Corporation | Kouji F.,Nippon Steel & Sumitomo Metal Corporation | Masamichi S.,Nippon Steel & Sumitomo Metal Corporation | And 7 more authors.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2011

Recently, ultra high strength steel plate (in this study, over 780N/mm 2 class steel is called 'ultra') such as 1000N/mm2 class strength is focused as material of various type of steel structure. 1000N/mm2 class steel has already applied in hydropower plant in order to enjoy its effect on cost reduction. However, in building construction field, high strength steel remains unfamiliar material. There are only a few example of application of 780N/mm2 class strength steel in building field. On the other hand, safety issue in a huge earthquake is more focused recently. Very large extent of elastic region of ultra high strength steel come to the front. Authors started the investigation of application of 1000N/mm 2 class steel plate for buildings. When ultra high strength steel is investigated, welding always become an issue. However, authors think welding is absolutely necessary in assembling steel material for buildings because welding is the most common and economic way of joining the materials at the moment. In this report, welding material, which can match 1000N/mm2 class steel plate and can optimize the properties of welded joint, has been developed. Especially wide range of inter-pass temperature and heat input is tried to be available. By controlling carbon equivalent and oxygen content of deposit metal, finally new welding material of GMAW and SAW for building has been developed.


Takai T.,Osaka City University | Yamaguchi T.,Osaka City University | Peng X.,Katayama Stratech Corporation | Yamashina K.,Osaka City University
IABSE Conference, Nara 2015: Elegance in Structures - Report | Year: 2015

This study focuses on fabrication tolerance of high strength bolted friction type joint. The investigation of past researches and experimental and FEM analytical results provides statistical characteristics of fabrication variation related to strength of the joint. The characteristic value shows that the variation of the thickness of coating hardly affects the slip strength of the joint. Furthermore, the influence of other variations is evaluated by the FEM analysis. This paper cleared predominant factors of fabrication tolerances affects slip strength of the joint.


Honda H.,Kanazawa Institute of Technology | Nakada Y.,Katayama Stratech Corporation
WCTE 2014 - World Conference on Timber Engineering, Proceedings | Year: 2014

The objected bridge is Yusuhara Bridge made by glulam timber and constructed in Kochi prefecture on 2007. To investigate design factors, static and dynamic performance, structural rigidity, vibration serviceability, and store of initial data for maintenance, the static and dynamic field tests of the bridge were done using one dump truck in August 2007. The structural performance on static and dynamic were investigated in the terms such as static deflection, response vibration, dynamic characteristics, dynamic increment factor and vibration serviceability. Furthermore, three-dimensional static and dynamic structural analyses of the bridge were conducted using FEM. From the comparison of dynamic characteristics between the subjected bridge and 22 modern timber bridges used glulam timber measured by authors in the past in Japan, this study gives a valuable data to evaluate dynamic performance for modern timber highway bridges.


Agano Y.,Katayama Stratech Corporation | Fujihira S.,Katayama Stratech Corporation | Lee S.H.,Osaka University | Kim Y.C.,Osaka University
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management | Year: 2010

From the viewpoint of repair/reinforcement, welding under loading is important because of the economical and social benefit. The soundness of welding structure can be investigated with the detection of defects. In welded structure, it is thought that the crack in welds may be related to collapse of structure. So, the investigation on the relation between the weld crack and acting loads in repair/reinforcement work by welding is very important. In this paper, performing CO 2 arc welding under static and cyclic loads, examinations for detection of the crack were carried out. In case of welding under static loads, the cracks were not observed. But, in case of welding under cyclic loads, the hot cracks were observed at I-type joints. From the results of fractography, pattern of fracture was projections of cellular dendrite and striations. And it could be known that the magnitude of Δ δ influenced the hot crack in the weld metal. © 2010 Taylor & Francis Group, London.


Agano Y.,Katayama Stratech Corporation | Lee S.-H.,Osaka University | Fujihira S.,Katayama Stratech Corporation | Kim Y.-C.,Osaka University
Welding International | Year: 2015

In welded structures, it is thought that the crack in welds may be related to collapse of structure. So, the investigation on the relation between weld crack and acting loads in repair/reinforcement work by welding is performed. There are three kinds of load conditions in welding of the site: no loads, static loads and fluctuated loads. In the previous paper, welding under static loads was carried out, it was confirmed that weld crack was not generated. In this case, installation of bents and traffic control were required. So, concerning the social and economical situation, welding under fluctuated loads without traffic control was desirable. In this paper, we performed CO2 arc welding under cyclic loads on the assumption that fluctuated loads, examinations for detection of the crack were carried out. The hot cracks were observed at I-type joints. From the results of fractography, projections of cellular dendrite and striations were observed. And it was known that the magnitude of root gap opening displacement (Δδ) and heat input (Q) was induced the hot crack in the weld metal. © 2014, © 2013 Taylor & Francis.


Agano Y.,Katayama Stratech Corporation | Lee S.-H.,Osaka University | Fujihira S.,Katayama Stratech Corporation | Kim Y.-C.,Osaka University
Welding International | Year: 2015

Experiments under static loads were carried out in order to investigate the possibility of repair/reinforcement by welding. Preventing the influence on the experimental devices due to the welding current by isolating between the jigs and the experimental devices, the stable experiments could be carried out. For the cruciform joints and I-shape joints, semi-auto CO2 gas welding was carried out under compressive static loads on the assumption of the dead load. As the experimental results, any cracks were not found. In the cruciform joints with multi-pass welding, there was a tendency that the longer the weld length became, the larger the magnitude of out-of-plane displacement became. In the actual construction, it was verified that repair welding under static loads could be carried out without welding defects by confirming repair weld length, heat input, inter-pass temperature and so on. © 2014, © 2013 Taylor & Francis.

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