Equivalent plastic hinge length of sleeve connected precast bridge piers

The paper proposes a method to calculate the deformation capacity of sleeve connected precast piers by assuming different curvature distributions for three types of damage forms. It also presents a calculation method for the displacement capacity of the top of precast piers. The study analyzes test data from 46 sleeve-connected precast piers to determine the classification of the three damage forms and the impact of design parameters on the plastic hinge length. Additionally, an equivalent plastic hinge model for precast piers with sleeve connections is established, considering bending, shear, longitudinal bar slip, and sleeve length. The F-Delta curve is determined through the utilization of the suggested equivalent plastic hinge model and the cast-in-place (CIP) based equivalent plastic hinge model, and the test results of three precast piers are compared. The results show that the precast pier with sleeve connection can experience three distinct types of damage: the pier bottom damage, the double plastic hinge zone damage and the sleeve top damage. According to the theory of correlation degree, the damage form of precast piers is more significantly affected by the axial compression ratio, while its impact on the equivalent plastic hinge length is relatively smaller. As the axial compression ratio increases, the influence of sleeve length on the equivalent plastic hinge length also increases. The proposed four parameter calibration equation for the equivalent plastic hinge length in this study has highly correlated properties. This equation demonstrates improved accuracy in simulating the F-Delta curve for the three distinct damage forms when compared to the CIP model, and the calculated value is well fitted with the experimental value.