钢桥面板钻孔工艺对止裂效果的影响分析

Analysis on influence of drilling technics on crack arrest in steel bridge deck

考虑实桥顶板角焊缝疲劳裂纹止裂孔的钻孔角度、钻孔偏心角度和钻孔深度,建立了顶板与U肋有限元模型,得到了桥面板顶板顶面与底面止裂孔两侧的应力分布情况。从孔边应力与裂纹扩展速率两个方面,对比不同参数下的止裂效果,提出了钻孔工艺参数的建议范围。研究结果表明:为了避免加速裂纹扩展,建议钻孔角度为0°~25°;对于焊趾裂纹,为了保证止裂孔孔周应力分布均匀,建议钻孔偏心角度为-15°~30°;对于未贯穿止裂孔,钻孔深度较浅时,其内侧应力较大且底面应力分布不均匀。

Finite element models for a bridge steel deck fillet welded with a U-Rib were established with consideration of stop-holes（for fatigue cracks of the fillet weld） of different drilling angles,eccentric angles and drilling depths. Stress distributions on top and bottom surfaces of the steel deck near the stop-holes were obtained. Based on the stresses around the holes and crack propagation rates,crack arrest effects of the holes were evaluated under different working conditions. The results show that drilling angle ranging from 0° to 25° is favorable to avoid acceleration of crack propagation. Eccentric angle between-15° and 30° is suggested to achieve a uniform stress distribution around stop-hole. Moreover,in terms of non-penetrating stop-holes,shallow depth of the stop-holes results in larger stress at the inner side and non-uniform stress distribution on bottom surface of the steel deck.