Experimental and Finite-Element Study of Buried Pipes Connected by Bellow Joint under Axial Cyclic Loading

Pipeline systems are vital but are often damaged severely under earthquake actions. Because a well-designed bellow joint has a high deformation capacity and low stiffness, it can be used as a connector to protect pipes. In this work, a pipe with a bellow joint was buried in a steel box filled with soil. The pipe was fixed at one end, and an axial cyclic displacement was applied at the other end. Strain, axial force, and deformation along the pipe were collected. Results indicate that all the deformation was concentrated at the joint, while the pipe experienced no damage and was fully functional after the test. A finite-element (FE) model respectively with and without a bellow joint was then developed to comparatively study the effectiveness of the joint. The results obtained from both experiments and FE analysis show that the bellow joint can efficiently reduce the axial force and increase the deformation capacity.