著者

佐藤 篤司 三井 和也 青山 雅弘

出版者

日本建築学会

雑誌

日本建築学会構造系論文集 (ISSN:13404202)

巻号頁・発行日

vol.82, no.736, pp.929-939, 2017 (Released:2017-06-30)

参考文献数

17

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Steel products which have various characteristic (e.g. high ductility, high yield stress, low yield stress and high weldability) are used as main structure of building by diversification of demanded application, and technology for steel manufacturing has developed. Because steel square tubular member is processed cold-forming and welding in the process of manufacturing, residual stress will exist in the products. Moreover, due to the cold-forming process geometrical initial imperfection, i.e., global and local, will exist. These initial imperfections are still remained even so the technology for steel manufacturing is developed. The influence of the initial imperfection on the performance of the column is well known. However, the effect of the initial imperfection on the elasto-plastic behavior of square steel tubular columns under compressive axial force with one end bending moment is not clarified. In this paper, firstly, the effect of initial imperfection (i.e., initial global imperfection, initial local imperfection or residual stress) on the elasto-plastic performance is investigated independently; comparison between the experimental results are shown. Secondly, the effect of composite initial imperfections on the elasto-plastic performance is investigated. Firstly, followings were found from the analysis results where initial imperfection is introduced in the member individually. 1) The amplitude of the global imperfection has an impact on performance of the column. Also, the direction of the global imperfection has an impact on performance of the column. When the ultimate behavior was determined by local buckling, the deformation capacity decreased with an increase the amplitude of global imperfection to windward. On the other hand, when the ultimate behavior was determined by bending deformation in in-plate, the deformation capacity increased with an increase the amplitude of global imperfection. 2) The amplitude of the local imperfection has a great impact on performance of the column. The maximum bending moment and the deformation capacity significantly decreased with an increase the amplitude of local imperfection. 3) The magnitude of the residual stress which changes in plate thickness direction hardly has an impact on performance of the column. However, the amplitude of the residual stress which does not change in plate thickness direction has an impact on performance of the column. Secondly, followings were found from the analysis results where composite initial imperfections are introduced in the member. 4) The amplitude of the local imperfection is the most influential initial imperfection on the deformation capacity of the column, and the deformation capacity decreased with an increase of the amplitude of local imperfection. The influence of the amplitude of the global imperfection is insignificant on the deformation capacity. On the other hand, the amplitude of the global and local imperfection and the magnitude of the residual stress do not have significant impact on the maximum bending moment. 5) Validation of the numerical simulation were also performed; initial imperfections that can simulate test results in reasonable accuracy was shown.