| A series of full-scale tests on longitudinal joints subjected to positive and negative moments were conducted. The joints were continuously loaded until completely damaged, and the development of joint opening, joint deflection, bolt strain and concrete strain with the bending moment were obtained. Based on the deformation and stress state of bolt, gasket and segment stress, the serviceability limit state of longitudinal joints were derived. The ultimate limit state of longitudinal joints was determined according to the ultimate bearing capacity of the joints. Finally, based on the comparison between the test results and the design results, the safety reserve of current safety factor design method was researched.