Test and Finite Element Analysis on Flexural Performance of Continuous T-beams with New Type Ultra-High Performance Concrete Wet Joint

In order to improve the crack resistance of ordinary concrete continuous girder bridges in the negative moment, the 1∶5 scale model girder was designed and subjected to the flexural test as a prototype of a 30 m prestressed concrete simple supported-continuous T-beam. The failure mode, mid-span load-displacement relationship and strain, crack distribution, and stiffness degeneration were investigated. The finite element model of the test beam was established using the finite element software ABAQUS, which was used to analyze the effect of different wet joint materials, concrete strength grades in the precast section, longitudinal reinforcement rates and UHPC tensile strength on the flexural performance of the beam. The test results showed that the new structural wet joint design was reasonable and can improve the overall stiffness, durability and safety of the beam to meet the actual requirements of the project. The introduction of UHPC could effectively limit the crack width, significantly increase the rigidity of normal concrete（NC） sections. The test values were well fitted with the model simulation values, indicating that the finite element model established had certain accuracy and applicability. The parameter analysis showed that improving the reinforcement ratio could significantly increase the ultimate bearing capacity and post-cracking stiffness of the beam, but had little effect on the cracking load and pre-cracking flexural properties. The use of UHPC instead of plain concrete C30 as the wet joint material obviously improved the load carrying capacity and stiffness of the beam, which verified the reasonableness of this design scheme. The tensile strength of UHPC could improve the ultimate load carrying capacity of the beam by a small margin, and had little effect on flexural capacity before cracking. While the tensile strength of UHPC had almost no effect on the load carrying capacity, stiffness and damage deflection of the whole beam.