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.