The Research of Strength Degradation Characteristics of CFRP-Repaired Pipes Under Fatigue Loads Based on Experimental and Numerical Analysis

The use of Carbon Fiber Reinforced Polymer (CFRP) for repairing defective pipes offers benefits such as a high strength-to-weight ratio and corrosion resistance. However, the strength of CFRP-repaired structures degrades under cyclic loading. This chapter presents an experimental investigation of the ultimate bending strength, fatigue life, and residual strength degradation of CFRP-repaired pipes subjected to fatigue loads. A fatigue cohesive zone model for the strength degradation of the interface between CFRP and steel pipes under fatigue loads is proposed. Considering the strength degradation of both the interface and the steel pipe under fatigue loads, a numerical model is established to analyze the residual strength of CFRP-repaired steel pipes under cyclic loads. The maximum discrepancy between the experimental and numerical results for residual strength is 4.13%, validating the accuracy of the numerical model. Through experimental and numerical analysis, the degradation characteristics of the residual strength of CFRP-repaired pipes are examined, providing a reference for the durability assessment of CFRP-repaired structures under cyclic loads.