MECHANICAL PERFORMANCE TEST OF PUSH-ON JOINT FOR DUCTILE IRON WATER SUPPLY PIPE AND PREDICTION MODEL OF THE FAILURE PROBABILITY

The investigation of mechanical characteristics and quantification of performance levels for buried water supply pipeline joints is important to promote the performance-based seismic design of segmented pipelines in engineering practice. The axial tensile tests were conducted on the push-on joints of ductile iron pipes, considering the effect of axial force and water pressure. The tensile mechanical characteristics and failure behavior of the push-on joints with different diameters were also compared in this study. The statistical characteristics between the peak tensile capacity and the deformation of the pipe joints were investigated based on the experimental results. In addition, an equation was proposed to estimate the tensile strength of pipe joints, and a failure criterion for pipe joints normalized by the leak opening was established. The study indicates that the water pressure ranging from 0 MPa to 0.3 MPa does not significantly affect the peak tensile capacity of ductile iron pipe joints. Moreover, the peak tensile capacity and the corresponding opening of ductile iron pipe joints exhibit a positive correlation. The mechanical model proposed for the pipe joints fits reasonably well with the experimental results. When the pipe joints are slightly damaged and functionally damaged, the joint openings are 52% and 60% of the installation depth, with a coefficient of variation of about 10.5% and 8.5%, respectively. The results can be used for the seismic performance assessment and design of buried segmented water supply pipelines.