Fatigue Properties of Subway Concrete Segments Repaired by HPM and GFRP

Abstract

The cracks of the reinforced concrete segment are the most important factor affecting the safety, and durability of tunnel structures. In this paper, a joint repair method of High Performance Polymer Matrix (HPM) and Glass Fiber Reinforced Polymer (GFRP) was proposed. The static and fatigue tests with or without crack repair were carried out by inclined beam loading on different reinforcement ratio segments. In static tests, after repair, the cracking load of LS12 and LS14 increased by 39% and 33%, respectively, and did not crack at the original crack location. HPM + GFRP significantly increases the stiffness of the member before yield, and the reinforcement ratio is the main factor affecting the stiffness after yield. In the fatigue test, the deflection and concrete strain of the HPM + GFRP repair specimens at the early stage of loading are reduced. With the accumulation of damage during fatigue cycles, HPM cracks and GFRP tensile force decreases, and the steel bar fatigue fracture will still occur in the final component. After 50,000 fatigue cycles, the residual bearing capacity of LD14 still reached more than 95% of the static strength, and the deflection increased only by no more than 3%, which is enough to prove that HPM material has good fatigue resistance, and GFRP can still effectively bond with concrete after fatigue loading.