著者

中野 達也 倉成 真也 田渕 基嗣

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.83, no.744, pp.321-331, 2018 (Released:2018-02-28)

参考文献数

12

被引用文献数

2

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In this study, beam-end connections of a steel structure using a pre-built-up H-shaped beams by submerged arc welding (SAW) are targeted, the structural characteristics is evaluated, the design and construction methods to prevent early brittle fracture are investigated. In this paper, first the influence of the welding construction conditions to the toughness of SAW metal was investigated, next the influence of the toughness of SAW metal to the structural characteristics of the beam-end connection were investigated by the full-scale cyclic loading test. The influence of the welding construction conditions to the toughness of SAW metal was investigated for two kinds of weld metals. One is a fillet weld metal by one-pass of tandem electrodes SAW, the other is a weld metal by multi-layer and multi-pass of single electrode SAW conforming to JIS. The test results showed that the toughness of the fillet weld metal was lower than that of the JIS weld metal. The toughness of SAW metal depended on a flux, was less affected by a steel material and a welding wire. The Charpy absorbed energy at 0°C (vE0) increased with the increase of the basicity of the flux. The fracture situation and the structural characteristics of the beam-end connection were investigated by the full-scale cyclic loading test in which the parameter is the toughness of SAW metal. Three specimens were provided, vE0 of SAW metal is 15J, 48J and 59J. In all the specimens, vE0 of the base metal of beam flange was 165J and the non-welding part remained in the fillet weld by SAW. In test result of all specimens, the point of crack initiation was the bottom of weld access hole and the brittle fracture occurred at the beam-end flange joint. The conversion position from ductile fracture to brittle fracture is inside SAW metal in case that vE0 of SAW metal is 15J, near SAW bond line in case that vE0 of SAW metal is 48J and 59J. As for the structural characteristics of the beam-end connection, it became clear that the maximum bending strength and the plastic deformation capacity of the beam-end connection increased with the increase of the toughness of the SAW metal in the range where the toughness is low. In case that vE0 of SAW metal is 15J, the plastic deformation capacity was about 40% of the required performance. On the other hand, in cases that vE0 is 48J and 59J, the required performance was satisfied. From the above results, it is considered that the influence of the toughness of SAW metal to the plastic deformation capacity of the beam-end connection using pre-built-up H-shaped beam is serious. It is certain that early brittle fracture occurred in case that SAW metal had low toughness, even though the base metal of beam flange had high toughness. On the other hand, it became clear that the plastic deformation capacity exceeding the required performance can be obtained by ensuring the toughness of SAW metal, even if the brittle failure occurred. If the weld access hole are provided at the beam-end connection using pre-built-up H-shaped beam, it is necessary to ensure the toughness of SAW metal by paying attention to the selection of the wire and the flux used for SAW.