Anti-Cracking Property of UHPC-NC Structure in the Negative Moment Zone of PC Beam Bridge

To improve the anti-cracking performance of the negative bending moment zone of the continuous prefabricated beam bridge, this paper proposed a UHPC-NC (normal concrete) structure with a high reinforcement ratio (larger than 1.5%) in the negative bending moment zone of an assembly continuous beam bridge. Taking A PC continuous beam bridge on the Nanchang to Jiujiang expressway as the engineering prototype, the study carried out the scale model tests with the scale ratio of 1.4 in the transverse direction and 1.5 in the longitudinal direction. Then, based on the "plane section" assumption, it developed the calculation methods formula of the cracking moment for the connection structure under different bearing modes. The influences of the thickness of the UHPC layer and reinforcement ratio on the cracking moment were analyzed by means of the finite element method. The results show that the cracking moment with the UHPC layer in the negative moment zone of the continuous girder bridge is improved significantly. The feasibility of the connection structure and the validity of the finite element model were verified and the calculation method of cracking moment in this paper is reliable and can provide reference for design and engineering application. the relative error of the reinforcement ratio between the finite element method and the method in this paper is within 10%. Under the action of pure moment and bending shear combination, the cracking moment of UHPC-NC structure increases with the increase of UHPC layer thickness and reinforcement ratio.