INTERFACIAL SHEAR CHARACTERISTICS OF CORRODED STEEL PLATE REPAIRED BY ROOM TEMPERATURE CIPP

Direct shear tests were conducted on Cured-In-Place Pipe (CIPP) repairs of corroded steel plate (CS) composite structures, utilizing Digital Image Correlation (DIC) technology. The variations in interface yield displacement, failure displacement, and peak shear force under different corrosion parameters and shear directions were investigated and the results were compared with finite element simulation outcomes. The findings indicate that the CIPP-CS interface exhibits four-stage brittle failure: elastic, yield, transient failure and, dynamic slip. Corrosion defects significantly increased the interface yield displacement. The interface shear strength improved with the increasing corrosion depth and corrosion radius, with corrosion depth having a more substantial effect than corrosion radius. The influence of defect shape on shear strength decreased in the order of square, circular, and elliptical defects. The shear strength was significantly higher when shearing along the short axis of elliptical defects and the sides of circular defects, compared to the long axis and primary face. In comparison to non-corroded conditions, a critical peak shear force was observed between corrosion depths from 4.0 mm to 5.0 mm and corrosion radii from 30 mm to 35 mm. The color gradient of the displacement field displayed a layered evolution towards the fixed end and bottom of the specimen, while the strain field exhibited negative stress concentration at the fixed end. Corrosion defects caused positive stress concentration at the CIPP position of the composite structure’s fixed end, which intensified and weakened with the increase of corrosion depth and radius, while it intensified with larger interaction angles. Boundary defects significantly altered the evolution patterns of the interface displacement field and strain one.