Interfacial Shear Transfer between Steel H-Piles and Concrete Encased in CFRP

Numerous in-service steel H-piles, a common structural element in the bridge industry, suffer severe corrosion. One of the adopted solutions is to use concrete jackets to encase the corroded sections. Therefore, interfacial shear strength between the uncorroded section and the jacket is crucial. This paper presents an experimental investigation of the interfacial shear stresses of 18 full-scale H-piles encased in concrete jackets and subjected to push-out static testing. The concrete jackets are confined using different carbon fiber–reinforced polymer (CFRP) confinement ratios. Different cross-sectional areas and distributions of shear studs are investigated. The average and maximum bond stresses are evaluated and compared with different design codes. Using CFRP confinement only increased the average interfacial shear stresses by up to 58%, while the shear studs increased it by 583% compared with the reference specimen. Combining shear studs and CFRP confinement increases the interfacial shear stresses by 1,033%. An equation is proposed to address the deficiency and rectify the critical oversight of overlooking the combined CFRP confinement and shear studs in the current design codes and standards in elevating interfacial shear stress, thereby significantly enhancing the interfacial shear stress in structural applications.