Seismic Fragility Study of Fire Sprinkler Piping Systems

A numerical modeling method was developed for fire sprinkler piping systems with threaded/grooved joints and used to generate seismic fragility parameters. The model accounts for the inelastic response of grooved/threaded joints, braces, hangers, and wire restrainers. The model incorporates a nonlinear model recently developed for the cyclic moment-rotation relationship of grooved tee joints, as well as a numerical model formerly developed for threaded tee joints. The models are validated using the results of extensive experiments on tee subassemblies performed at University at Buffalo. The model is adaptable to different pipe diameter joints. A real fire sprinkler system of a hospital was simulated and its seismic response was obtained under a suite of ninety-six artificially generated tri-axial floor acceleration records. Three system damage states were defined and a combined probabilistic seismic demand model was utilized to obtain system-level fragility parameters.