Simplified Modeling and Detailed Crack Propagation Analysis for Cracked Pipes

Two analysis approaches for a cracked pipe subjected to a seismic load were focused on. The first approach is a simplified modeling technique using a nonlinear spring element. A degrading model called a deteriorating distributed element was improved to simulate the asymmetric and degrading behavior of a cracked pipe. The second approach is a detailed crack propagation analysis using the finite element method (FEM). This approach is based on fracture mechanics, and crack growth is determined by using fracture parameters such as the J-integral range obtained from the FEM. Iterative re-meshing of the analysis model using solid elements was conducted to evaluate fatigue crack growth for cyclic loads. These two approaches were applied to a cracked pipe test. In comparing the test results, it was confirmed that the simplified modeling and detailed analysis approaches are applicable to a seismic analysis for a cracked pipe.