混凝土脱空修复对角钢连接件力学性能影响

Impact of Concrete Void Repair on Mechanical Performance of Angle Steel Connectors

为探索钢壳混凝土角钢连接件根部混凝土脱空对连接件抗剪性能的不利影响,提出合理的脱空修复方法,基于深中通道沉管隧道角钢连接件的局部构造,以脱空形状、脱空修复和混凝土强度为变化参数,设计8组足尺推出试件,并开展抗剪性能试验和有限元模拟分析。分析显示:1)普通混凝土试件先在角钢内部发生混凝土压溃破坏,试件破坏模式受脱空形式及脱空修复影响不明显;2)脱空对角钢连接件的抗剪承载力和抗剪刚度均有削弱影响,三棱柱整体脱空时角钢连接件的抗剪承载力和抗剪刚度可折减32.8%和76.9%;3)脱空修复对角钢连接件的抗剪承载力和抗剪刚度有提升作用,但由于修复料与脱空界面间难以协同受力,性能提升效果并不显著;4)考虑脱空处未修复,用超高性能混凝土替换普通混凝土时,推出试件的抗剪承载力较未脱空时提高77%,抗剪刚度较脱空时折减8.9%;5)超高性能混凝土的优良力学性能使角钢连接件的抗剪承载力得到明显提高,但由于脱空导致角钢连接件出现较大变形,因此无法有效提升脱空时的抗剪刚度;6)提高修复料力学性能对改善三棱柱脱空修复后的承载性能影响不明显。

The authors investigate how concrete voids located at the base of steel-shelled concrete angle connectors affect their shear performance and propose an effective repair method for these voids.Focusing on the angle steel connectors in the immersed tunnel of the Shenzhen-Zhongshan link,eight full-scale test specimens are designed.Shear performance tests and finite element simulations are conducted with varying parameters such as void shape,void repair,and concrete strength.The findings reveal that:(1)In ordinary concrete specimens,crush damage primarily occurs within the angle′s internal concrete,with the damage mode being minimally influenced by the void form and repair.(2)Concrete voids significantly reduce the shear bearing capacity and stiffness of angle steel connectors,with reductions of up to 32.8%and 76.9%,respectively,in specimens with a triangular prism void.(3)While void repair enhances the shear load capacity and stiffness of the connectors,the improvement is limited due to the challenges in achieving cohesive bonding between the repair material and the void interface.(4)Substituting ordinary concrete with ultra-high performance concrete(UHPC)without repairing the void increases the shear bearing capacity of the specimen by 77%compared to those without voids.However,the shear stiffness is decreased by 8.9%compared to specimens with voids.(5)Despite UHPC′s superior mechanical properties,it cannot effectively increase the shear stiffness due to significant deformation in the angle steel connectors caused by the voids.(6)Finite element analysis indicates that improving the mechanical properties of the repair material does not significantly enhance the shear bearing capacity post-void repair in triangular prism-shaped voids.