Simplified limit analysis of pipelines with multi-defects

The load carrying capacities of pipelines with three defects of four configurations and dimensions are determined by a simplified numerical method for both lower and upper bound limit analyses of 3-D structures. Combining the previous load-carrying capacities of 3-D pipelines with both one and two part-through defects, the effects of the number of defects on the load-carrying capacity of pipelines with multi-defects along the pipeline axis are investigated in detail. The admissible displacements and failure modes of defective pipelines under the action of various loading forms are discussed. The numerical results confirm the applicability of the procedure.