To help assess business continuity in buildings subjected to earthquakes, a research project was initiated to simplify and isolate evaluation of the fragility curves of the plumbing system, estimating the degree of damage to the plumbing system without directly monitoring nonstructural members like partition walls. The project team faced difficulties formulating the natural mode shape of the plumbing system for various forms under varying boundary conditions. They needed flexible, comprehensive structural modeling and analysis technology.

They selected AutoPIPE pipe stress analysis software to generate an analytical model, evaluating the natural frequency and confirming the natural mode shape of a basic plumbing system. Using Bentley’s application, they changed the combination of boundary conditions and seismic loads within the model, verifying that the proposed fragility evaluation can be derived from simplified analytical models. The solution confirmed that the bending moment of a plumbing system subjected to seismic loading is maximized at the fixed points in the piping network.