FRP-UHPC复合加固锈蚀RC柱抗侧向冲击性能研究

Study on the Lateral Impact Resistance of Corroded RC Columns Strengthened with FRP-UHPC Composite

摘要: 在海洋等侵蚀环境中，钢筋混凝土(RC)柱易发生钢筋锈蚀，从而在轴压与侧向冲击耦合作用下表现出显著的性能退化。然而，关于FRP格栅-UHPC复合加固锈蚀RC柱在冲击荷载下的动力响应及破坏机制仍缺乏系统研究。本文基于冲击试验结果，建立并验证了未加固及FRP格栅-UHPC加固RC柱的有限元模型，并进一步引入考虑钢筋截面削弱、黏结退化及锈胀效应的锈蚀模拟方法。系统分析了锈蚀率、加固形式、冲击速度及FRP格栅层数对构件动力响应及破坏机制的影响。结果表明：钢筋锈蚀会加剧柱底损伤集中，使破坏模式由弯剪主导向压剪主导转变。UHPC加固层可提高局部刚度与抗剪能力，减轻原混凝土损伤；FRP格栅增强加固层的拉力传递能力，从而提高整体协同受力及耗能能力。与单独UHPC加固相比，FRP格栅-UHPC复合加固可使构件总内能提高约8%。随着冲击速度增加，损伤范围扩大且峰值与残余位移增大；增加FRP层数虽能改善变形控制能力，但对总耗能提升有限。研究成果可为侵蚀环境中RC柱抗冲击性能评估及加固设计提供参考。

Abstract: In corrosive environments such as marine regions, reinforced concrete (RC) columns are susceptible to reinforcement corrosion, which results in significant deterioration in structural performance under the coupled action of axial compression and lateral impact loading. However, systematic studies on the dynamic response and failure mechanisms of corroded RC columns strengthened with FRP grid-UHPC composites under impact loading remain limited. Based on impact test results, finite element (FE) models of unstrengthened and FRP grid-UHPC strengthened RC columns were established and validated in this study. A corrosion simulation approach considering reinforcement cross-sectional reduction, bond degradation, and rust expansion effects was further incorporated into the FE models. The effects of corrosion rate, strengthening scheme, impact velocity, and number of FRP grid layers on the dynamic response and failure mechanisms of the specimens were systematically investigated. The results indicate that reinforcement corrosion aggravates damage concentration at the column base, causing the failure mode to shift from flexure-shear dominated failure to compression-shear dominated failure. The UHPC strengthening layer enhances local stiffness and shear resistance, thereby mitigating damage to the original concrete. Moreover, the FRP grid enhances the tensile force transfer capacity of the strengthening layer, thereby improving the overall composite action and energy dissipation capacity. Compared with UHPC strengthening alone, FRP grid-UHPC composite strengthening increases the total internal energy of the member by approximately 8%. With increasing impact velocity, the damage region expands, and both peak and residual displacements increase significantly. Increasing the number of FRP grid layers improves deformation control capability, although its contribution to the enhancement of total energy dissipation is limited. The findings of this study can provide a reference for the impact resistance assessment and strengthening design of RC columns in corrosive environments.