GFRP管夹层灌浆修复锈蚀圆钢管T形节点受压性能研究

为研究GFRP管夹层灌浆修复锈蚀钢管节点的受压性能，改变支主管直径比、锈蚀率及修复构造，完成8个T形圆钢管节点的支管轴向受压静力加载试验。通过对主管加速锈蚀及GFRP管夹层进行灌浆修复，实测各钢管节点的破坏模式、荷载 变形曲线和荷载 应变曲线，分析节点受压承载力和初始刚度。结果表明：质量损失10%的主管锈蚀会使T形圆钢管节点受压承载力下降近20%，但未改变节点的失效模式；主管GFRP管夹层灌浆修复使锈蚀T形圆钢管节点的受压承载力提高100%左右，且较未锈蚀对比T形圆钢管节点可提高约70%；GFRP外管的约束作用是提升节点受压性能的关键，采用无约束作用的PVC外管会使灌浆层过早开裂并剥离，修复效果一般；主管焊接连接键可以增强钢管与灌浆夹层之间的锚固，其对PVC管夹层灌浆修复锈蚀节点的提升作用更明显，但对有GFRP约束修复T形圆钢管节点的贡献很小。建立并验证了各类T形圆钢管节点的有限元模型，揭示未修复节点主管塑性化变形失效机制，以及GFRP管夹层灌浆的约束作用对于锈蚀节点受压性能的提升机理。

Investigation on compressive behavior of grout-filled GFRP tube repairing corroded CHS T-joint

In order to study the compressive performance of grout-filled GFRP tube repairing corroded joints, eight CHS T-joints with different brace to chord diameter ratios, corrosion ratios, and repairing configurations were tested under brace axial compressive loading. The scheme of the chord accelerated corrosion, as well as the grout-filled GFRP tube repairing method, was introduced. The failure modes, load-deformation curves, and load-strain curves of the specimens were measured, and the compressive strength and initial stiffness of the joints were analyzed. The results demonstrate that corrosion chord with 10% weight loss will lead to about a 20% reduction in the compressive strength of the CHS T-joint while the failure mode of the corroded joint is similar to the uncorroded ones. The compressive strength of the grout-filled GFRP tube retrofitted CHS T-joints is about two times the corresponding corroded ones, and even 70% higher than that of the uncorroded ones. JP]The restraint effect of an external GFRP tube is critical to improving the joint compressive performance, and the grouting layer without a GFRP tube will crack and peel prematurely, which can only achieve a little repairing effect. The bars welded on the chord enhance the bonding effect between the steel pipe and the grouting layer, and play an effective role in the enhancement of specimens without GFRP tube while having a little contribution to the reinforcement of specimens with a GFRP tube. The numerical models of the CHS T-joints were developed and validated. The plastic damage failure mechanism of chord for unrepaired joints as well as the compressive performance enhancement rules for corroded CHS T-joints under the constraint of the grout-filled GFRP tube was revealed.