Mechanical analysis and parameter design of CFRP-Wrapped defected steel pipe

Abstract

Externally wrapped carbon fiber reinforced polymer (CFRP) composites are effective to strengthen the defected steel pipes. However, the effects of thickness and mechanical properties of pipe substrate, CFRP, and putty are still unclear. In the present study, an analytical model based on the Tresca yield criterion and failure mode of CFRP-wrapped defected pipe was proposed to calculate the stress and yield/burst pressure. The analytical model was verified by the burst test and finite element (FE) analysis. The effects of Poisson's ratio, modulus, and thickness of the putty and CFRP on stress and load bearing capacity were analyzed quantitatively by the analytical model. The analytical model is accurate and conservative due to the Tresca criterion and the assumption of ideal elastic-plastic. For putty, a larger modulus and smaller thickness can reduce the stress of pipe substrate and improve the yield pressure. The yield and burst pressures are dominated by the CFRP thickness and modulus. A dimensionless model of yield pressure was established and the critical dimensionless CFRP modulus and thickness making the yield pressure of the strengthened pipe greater than the operating pressure of the original pipe were determined.