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RISS 인기검색어
- 검색키워드
- 저자 : Shogo Kiyokawa (검색결과 3 건)
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Shogo Kiyokawa,Kazuo Tateishi,Takeshi Hanji,Masaru Shimizu 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4
In current design codes, the minimum bolt spacing and edge distance for high-strength bolted friction joints are specifi ed based on the bolt diameter, regardless of the plate thickness or steel strength. However, the mechanical performance of joints with a more compact bolt spacing than that given in the current design specifi cations has been little examined. In this study, the slip and ultimate strength of high-strength bolted joints with a compact bolt spacing and edge distance were investigated. Tensile tests were conducted on friction-type joints with various bolt arrangements. The use of a compact bolt arrangement was not observed to have a negative infl uence on the slip strength in these tests. The estimated strengths corresponding to the experimentally observed failure modes were found to agree fairly well with the experimental results within a 10% error. A parametric fi nite element analysis was also conducted to investigate the infl uence of the bolt arrangement on the slip coeffi cient. It was concluded that the bolt spacing and edge distance have little infl uence on the slip coeffi cient.
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Reduction of Stress Concentration at Stop-Hole by Bolting a Crack
Toshiyuki Ishikawa,Shogo Kiyokawa,Wataru Nakatsuji 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.6
A stop-hole, which is drilling at the crack tip, is one of the famous tentative repairs of fatigue cracks in steel structures. When the crack becomes longer, the stress concentration of the stop-hole also increases. Therefore, during the tentative repair of long fatigue cracks, the chances for re-initiation of the fatigue cracks from the stop holes are high. The bolting stop-hole method is a useful technique against fatigue cracks. In this technique, bolting is applied only for the stop-holes at the crack tips. Therefore, as the crack length increases, the eff ect of the bolting stop-hole method decreases. In this paper, the authors propose a stress concentration reduction technique for a stop-hole by bolting the fatigue crack between stop-holes. The eff ect of the proposed technique was verifi ed by tensile and bending tests of specimens as well as fi nite element analysis. From the tensile and bending tests, it was clarifi ed that the stress concentration of the stop-hole was drastically reduced by bolting a crack under the condition before the slippage of bolts. Additionally, multi-bolting cracks have the advantage of improving the slippage load of the bolts in a crack. Furthermore, fi nite element analysis verifi ed the reduction in stress concentration of the stop-hole by bolting a crack, and the eff ectiveness of bolting cracks and stop-holes was also shown.
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Noboru Konda,Masaru Nishio,Mitsuru Ichimiya,Toshihiro Kasugai,Shogo Kiyokawa 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.1
Under heavy traffic conditions, some fatigue cracks have been found at welding joints between U-shaped ribs “trough ribs”and deck plates. Fatigue cracks along thickness direction of deck plate from root tip are important because visual crack detection from outside is limited. In this paper, new functional steel plates with initiation resistance of fatigue crack at weldment and propagation resistance at base material are applied to deck plate to evaluate improvement of fatigue life. We conducted fixed-point fatigue tests with real scale partial models consisted with one trough rib and a transverse girder, and the elastic FEM (Finite Element Method) analysis corresponding to the fatigue test specimen. Based on these results, we studied the fatigue properties which focused on the difference between conventional steel plates and newly developed steel plates, FCA (Fatigue Crack Arrester). Fatigue cracks were initiated from root tip of welded joints between a trough rib and a deck plate. It is clarified that FCA steel plates instead of conventional steel plates can improve the fatigue life under the same welding conditions. This improvement effect becomes much clearer in the high cycle region, which is noticeable at the operation and management stage of bridges.
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