Experimental study and finite element model of 3-ply bellows expansion joints system subjected to monotonic load

Piping systems are vital in various industries and infrastructure networks but are vulnerable to damage from seismic activity, liquefaction, ground subsidence, and other factors. Damage to piping systems occurs mainly at the connections due to earthquakes, ground subsidence, and liquefaction. To ensure the safety of piping systems, this study developed a 3-ply bellows expansion joint capable of withstanding deformation caused by earthquakes. In high load conditions, while a transitional 1-ply bellows expansion joint must be thickened for durability, the 3-ply bellows expansion joint is more accessible to manufacture and provides superior fatigue resistance. The seismic deformation performance of 3-ply bellows expansion joints was evaluated by performing four monotonic loading tests: tensile-compression, shear, and bending. Additionally, the complex behavior of a 3-ply bellows expansion joint was expressed by creating a simplified finite element model. Based on this, the finite element model was validated using bending monotonic loading test data for a piping system with two bellows expansion joints, and it was confirmed that the results were in good agreement. The constructed finite element model can serve as a tool for understanding the integrated behavior of piping systems, including the 3-ply bellows expansion joints.