The　nonlinear　mechanical　behaviour　of　pipeline　joints　influences　the　seismic　response　of　water　supply　pipelines.　This　study　presents　an　experimental　investigation　of　the　tensile　behaviour　of　push-on　joints　of　ductile　iron　(DI)　pipelines,　subjected　to　axial　tensile　forces　and　internal　water　pressure.　The　axial　performance　and　damage　states　of　joints　are　determined　for　push-on　joints　with　different　diameters.　A　statistical　analysis　is　then　conducted　to　determine　the　correlation　between　tensile　strength　and　joint　opening.　An　empirical　equation　for　estimating　the　tensile　strength　of　pipeline　joints　is　proposed,　along　with　a　normalized　failure　criterion　for　joint　opening　considering　water　leakage.　Moreover,　a　numerical　model　for　buried　pipelines　considering　nonlinear　soil-pipe　interaction　is　developed.　Incremental　dynamic　analysis　(IDA)　is　performed　on　DI　pipelines　with　explicit　consideration　of　the　uncertainty　of　joint　mechanical　properties.　Seismic　fragility　curves　are　developed　based　on　the　IDA　results.　The　effect　of　mechanical　parameter　uncertainty　of　pipeline　joints　on　seismic　risk　assessment　of　segmented　pipelines　is　quantitatively　evaluated.　The　numerical　results　indicated　that　the　failure　probability　of　the　pipeline　considering　the　uncertainty　of　joint　mechanical　properties　is　approximately　1.5　to　2　times　larger　than　that　predicted　by　a　deterministic　model.