粘贴角形钢板加固顶板-U肋焊喉疲劳裂纹试验研究

Experimental Study on U Rib-to-deck Welding Throat Fatigue Cracks Strengthened by Bonding Angle-shaped Steel

摘要:

为了研究粘贴角形钢板对钢桥面板顶板?U肋焊喉疲劳裂纹的修复效果，首先对关注细节的疲劳破坏模式和加固后疲劳性能的提升开展试验和理论研究，然后基于Abaqus有限元软件建立线弹性断裂力学模型，结合最大周向应力准则探究不同裂纹深度和初始倾角对裂纹扩展特性的影响，并在此基础上验证了粘贴角形钢板对疲劳裂纹的加固效果。结果表明，U肋腹板面外弯曲变形是导致顶板?U肋焊喉疲劳开裂的控制因素。该裂纹属于以Ⅰ型为主导的复合型疲劳裂纹，等效应力强度因子随裂纹深度增加而增大，且当初始倾角接近45°时达到最大。所预测的裂纹扩展行为与试验观测结果近乎一致，扩展路径与顶板夹角介于30°~45°之间。对比未加固试件，加固后相应开裂部位关键测点的疲劳应力幅降低90.5%，疲劳寿命显著延长，且粘贴层完好。

Abstract:

In order to study the repair effect of bonding angle-shaped steels on the welding throat fatigue crack of the U rib-to-deck in steel bridge decks， experimental and theoretical study was firstly carried out on the fatigue failure modes of concerned detail and the fatigue improvement after reinforcement. Then， the corresponding linear elastic fracture mechanics models were established based on Abaqus finite element software. The effects of different crack depths and initial dip angles on the crack propagation characteristics were investigated through the maximum circumferential stress criterion. On this basis， the strengthening effect of bonding angle-shaped steels on the fatigue details was verified. The results show that the out-of-plane bending deformation of the U-rib web is the controlling factor leading to fatigue cracking in the roof-U-rib welding throat. The fatigue crack is a composite fatigue crack dominated by type Ⅰ， and the equivalent stress intensity factor increases with the increase of crack depth， and reaches the maximum when the initial dip angle is close to 45°. The predicted crack propagation behavior is almost consistent with the experimental observations， and the angle between the propagation path and the top plate is between 30° and 45°. Compared with the un-strengthened specimens， the fatigue stress amplitude of the key measuring points of the corresponding cracked part is reduced by 90.5% after strengthening. Fatigue life can be significantly prolonged and the bonding layer is intact.