Reduction of Stress Concentration at Stop-Hole by Bolting a Crack

다국어 초록 (Multilingual Abstract)

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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