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 effect 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 effect of the proposed technique was verified by tensile and bending tests of specimens as well as finite element analysis. From the tensile and bending tests, it was clarified 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, finite element analysis verified the reduction in stress concentration of the stop-hole by bolting a crack, and the effectiveness of bolting cracks and stop-holes was also shown.

在裂纹尖端处钻出的挡孔是钢结构疲劳裂纹的初步尝试性修复方法之一。当裂纹变长时，堵孔的应力集中也增加。因此，在长疲劳裂纹的初步修复中，从止动孔重新产生疲劳裂纹的机会很高。螺栓止动孔法是一种抗疲劳裂纹的有用技术。在该技术中，螺栓仅应用于裂纹尖端处的止动孔。因此，随着裂纹长度的增加，螺栓固定孔法的效果降低。在本文中，作者提出了一种通过栓塞止动孔之间的疲劳裂纹来减小止动孔应力集中的技术。通过对样品进行拉伸和弯曲测试以及有限元分析，验证了所提出技术的效果。从拉伸和弯曲试验中可以看出，在螺栓打滑之前的条件下，通过开裂而使螺栓孔急剧减小，从而使止动孔的应力集中大大降低。另外，多螺栓裂纹具有改善裂纹中螺栓的滑动载荷的优点。此外，有限元分析验证了通过螺栓连接裂纹减少的应力集中，并且还显示了螺栓连接裂纹和卡孔的有效性。多螺栓裂纹的优点是可以改善裂纹中螺栓的滑移载荷。此外，有限元分析验证了通过螺栓连接裂纹减少的应力集中，并且还显示了螺栓连接裂纹和卡孔的有效性。多螺栓裂纹的优点是可以改善裂纹中螺栓的滑移载荷。此外，有限元分析验证了通过螺栓连接裂纹减少的应力集中，并且还显示了螺栓连接裂纹和卡孔的有效性。