Seismic response of pressurized fire sprinkler piping systems II: Numerical study

This second of two companion articles examines the efficiency of a number of hysteresis models to simulate the nonlinear moment-rotation behavior of sprinkler piping tee joints made of various materials and connection types. The proposed hysteresis models are capable of capturing the strength degradation, change of stiffness during unloading, as well as energy dissipation of full-scale sprinkler joints tested by the authors in a previous study. The hysteresis models were then embodied in nonlinear rotational springs at joints combined with elastic beam elements for the piping segments to capture the seismic response of full-scale fire sprinkler piping systems. These system level numerical models were validated through simulations based on the seismic tests presented in the first companion article. Nonlinear dynamic response-history analyses adequately predict the seismic response of the test specimens in terms of displacement, acceleration, and moment-rotation at the piping joints. The proposed numerical models represent a useful tool to assess the seismic demands of pressurized fire sprinkler piping systems in buildings.